# Seminar 05: Diabetes Management
## Year 3: Internal Medicine Clerkship
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## Learning Objectives
By the end of this seminar, students will be able to:
1. Differentiate type 1 and type 2 diabetes mellitus
2. Describe diagnostic criteria and screening recommendations
3. Explain treatment goals and monitoring strategies
4. Describe pharmacologic management of type 2 diabetes
5. Apply insulin therapy principles
6. Recognize and manage acute diabetic emergencies
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## Seminar Outline
### I. Overview and Classification
Diabetes mellitus encompasses a group of metabolic disorders characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Type 1 diabetes results from autoimmune destruction of pancreatic beta cells, leading to absolute insulin deficiency and requiring lifelong exogenous insulin therapy. Type 2 diabetes, the most common form accounting for approximately 90-95% of cases, involves a combination of insulin resistance in peripheral tissues and progressive beta-cell dysfunction with relative insulin deficiency. Gestational diabetes develops during pregnancy and increases the risk of both mother and offspring developing type 2 diabetes later in life.
Type 1 diabetes typically presents in children and young adults, often with acute symptoms including polyuria, polydipsia, weight loss, and potentially diabetic ketoacidosis as the initial presentation. Autoantibodies including anti-GAD65, anti-islet cell antibodies, and anti-insulin antibodies are present in most patients before clinical onset and help distinguish type 1 from other forms. The pathophysiology involves T-cell mediated destruction of beta cells, often triggered by environmental factors in genetically susceptible individuals. Patients with type 1 diabetes have an absolute requirement for insulin therapy from diagnosis, as they lack sufficient endogenous insulin production.
Type 2 diabetes develops more insidiously, often over years, and is strongly associated with obesity, sedentary lifestyle, family history, and increasing age. The pathophysiology involves insulin resistance in muscle, liver, and adipose tissue, combined with progressive failure of beta cells to compensate through increased insulin secretion. Many patients remain undiagnosed for years because hyperglycemia develops gradually and may not cause classic symptoms until significantly elevated. Treatment approaches range from lifestyle modification alone to oral agents and eventually insulin as the disease progresses and beta-cell function declines.
Prediabetes represents an intermediate state of abnormal glucose metabolism that increases the risk of progression to type 2 diabetes by approximately 5-10% per year. Impaired fasting glucose is defined as fasting plasma glucose of 100-125 mg/dL, while impaired glucose tolerance refers to a 2-hour OGTT value of 140-199 mg/dL. Hemoglobin A1c values of 5.7-6.4% also indicate prediabetes and increased cardiovascular risk. Intensive lifestyle intervention with weight loss of 5-7% and moderate physical activity of 150 minutes per week can reduce progression to diabetes by approximately 58%, while metformin provides additional protection in high-risk individuals.
Panel A: Diagram illustrating the pathophysiology of type 1 versus type 2 diabetes, showing autoimmune beta-cell destruction in type 1 and insulin resistance with relative insulin deficiency in type 2. Panel B: Clinical timeline showing typical presentation patterns for type 1 (acute onset in youth) versus type 2 (insidious onset in adults). Panel C: Graph depicting the spectrum from normal glucose tolerance through prediabetes to diabetes with corresponding glucose and A1c values. Panel D: Comparison table showing key distinguishing features between type 1 and type 2 diabetes including age of onset, body habitus, C-peptide levels, and autoantibody status.
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### II. Diagnosis and Screening
The diagnosis of diabetes mellitus can be established using any one of four criteria, though confirmation with a second test is recommended in asymptomatic patients. Fasting plasma glucose of 126 mg/dL or higher, measured after no caloric intake for at least 8 hours, meets diagnostic criteria. A 2-hour plasma glucose of 200 mg/dL or higher during a 75-gram oral glucose tolerance test also establishes the diagnosis. Hemoglobin A1c of 6.5% or higher, performed using a certified standardized assay, provides an alternative criterion that reflects average glycemia over the preceding 2-3 months.
Random plasma glucose of 200 mg/dL or higher in a patient with classic symptoms of hyperglycemia, including polyuria, polydipsia, and unexplained weight loss, is sufficient for diagnosis without confirmatory testing. When two different tests are performed on the same sample and both exceed diagnostic thresholds, the diagnosis is confirmed. Discordant results from two tests performed on the same sample require repeating the abnormal test for confirmation. The choice of diagnostic test should consider clinical context, as A1c may be unreliable in conditions affecting red blood cell turnover including hemoglobinopathies, hemolytic anemia, and recent transfusion.
Screening for type 2 diabetes is recommended for adults aged 35 years and older, with repeat testing every 3 years if results are normal. Screening should be considered earlier and more frequently in individuals with body mass index of 25 kg/m2 or higher who have additional risk factors including first-degree relative with diabetes, high-risk ethnicity, history of cardiovascular disease, hypertension, HDL cholesterol below 35 mg/dL, triglycerides above 250 mg/dL, polycystic ovary syndrome, or physical inactivity. Women with a history of gestational diabetes should undergo lifelong screening every 3 years starting 6-12 weeks postpartum. Patients with prediabetes should be tested annually given their significantly elevated risk of progression.
Hemoglobin A1c provides important information about average glycemic control but has limitations that clinicians must understand. Each 1% change in A1c corresponds to approximately 28 mg/dL change in mean glucose, with an A1c of 6% correlating to an average glucose of approximately 126 mg/dL. Conditions that shorten red blood cell lifespan, including hemolysis, blood loss, and transfusion, falsely lower A1c values. Hemoglobin variants common in certain populations may interfere with some A1c assays. Alternative markers including fructosamine, which reflects glycemia over 2-3 weeks, and 1,5-anhydroglucitol may be useful when A1c is unreliable.
Panel A: Flowchart demonstrating the diagnostic algorithm for diabetes using fasting glucose, OGTT, A1c, or random glucose with symptoms. Panel B: Table showing diagnostic thresholds for normal, prediabetes, and diabetes for each testing modality. Panel C: Graph correlating hemoglobin A1c values with estimated average glucose levels. Panel D: Screening recommendations showing different populations, risk factors, and recommended testing intervals.
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### III. Treatment Goals
Glycemic targets must be individualized based on patient characteristics, with most non-pregnant adults having an A1c target below 7%. More stringent targets of A1c below 6.5% may be appropriate for patients with shorter duration of diabetes, long life expectancy, no significant cardiovascular disease, and low hypoglycemia risk, provided targets can be achieved without significant hypoglycemia. Less stringent targets of A1c below 8% or even higher may be appropriate for patients with history of severe hypoglycemia, limited life expectancy, advanced complications, extensive comorbidities, or longstanding diabetes where intensive control has been difficult to achieve. For patients with limited life expectancy or where risks outweigh benefits, the primary goal becomes avoiding symptomatic hyperglycemia and hypoglycemia rather than achieving specific numeric targets.
Self-monitoring of blood glucose provides important information for day-to-day decision-making, particularly for patients on insulin or other medications that cause hypoglycemia. Pre-meal glucose targets of 80-130 mg/dL are recommended for most adults, with peak postprandial glucose measured 1-2 hours after starting a meal targeted below 180 mg/dL. Time in range, defined as the percentage of time glucose values fall between 70-180 mg/dL, has emerged as an important metric with a target of greater than 70% for most patients. Continuous glucose monitoring provides comprehensive data on glucose patterns, trends, and variability that fingerstick testing cannot capture.
Comprehensive diabetes management extends beyond glycemic control to include aggressive cardiovascular risk factor management. Blood pressure targets of less than 130/80 mmHg are recommended for most patients with diabetes, with additional benefit from RAAS inhibition in those with albuminuria. Statin therapy is recommended for essentially all patients with diabetes aged 40-75 years, with intensity based on cardiovascular risk assessment and LDL cholesterol targets of less than 70 mg/dL for very high-risk patients or less than 100 mg/dL for others. Aspirin therapy is recommended for secondary prevention in patients with established atherosclerotic cardiovascular disease, while primary prevention recommendations depend on individual risk assessment and patient preferences.
Regular monitoring and assessment should occur at appropriate intervals to optimize outcomes and detect complications early. Hemoglobin A1c should be measured at least twice yearly in patients meeting goals and quarterly in those not meeting targets or with therapy changes. Annual screening for diabetic kidney disease using both estimated GFR and urine albumin-to-creatinine ratio is essential. Dilated eye examinations should occur annually or as recommended by ophthalmology. Comprehensive foot examinations including inspection, monofilament testing, and assessment of pedal pulses should occur at every visit or at least annually.
Panel A: Table showing individualized A1c targets based on patient factors including life expectancy, hypoglycemia risk, comorbidities, and diabetes duration. Panel B: Self-monitoring targets showing recommended glucose ranges for fasting, pre-meal, and post-meal measurements. Panel C: Comprehensive cardiovascular risk management targets including blood pressure, lipids, and antiplatelet therapy. Panel D: Monitoring schedule showing recommended frequency of A1c, kidney function, eye exams, and foot exams.
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### IV. Lifestyle Management
Medical nutrition therapy is a cornerstone of diabetes management that should be individualized based on metabolic goals, cultural preferences, and personal factors. There is no single optimal macronutrient distribution, though most eating patterns that reduce overall carbohydrate intake, emphasize non-starchy vegetables, minimize added sugars and refined grains, and focus on whole foods improve glycemia. Fiber intake should be at least 14 grams per 1000 kilocalories, ideally from vegetable, legume, and whole grain sources. Protein should comprise approximately 15-20% of calories for patients without diabetic kidney disease, and fat intake should emphasize unsaturated sources while limiting saturated and trans fats.
Physical activity provides multiple benefits including improved glycemic control, cardiovascular risk reduction, weight management, and psychological well-being. Adults with diabetes should engage in at least 150 minutes per week of moderate-intensity aerobic activity, spread over at least 3 days with no more than 2 consecutive days without exercise. Resistance training involving all major muscle groups should occur at least 2-3 days per week, as it independently improves insulin sensitivity and glycemic control. Prolonged sitting should be interrupted every 30 minutes with brief periods of standing, walking, or other light physical activity, particularly for individuals with type 2 diabetes.
Weight management profoundly impacts metabolic outcomes, with even modest weight loss providing significant benefits. Weight loss of 5% improves glycemia, lipids, and blood pressure, while 10% or more weight loss can result in disease-modifying effects including diabetes remission in some patients. Metabolic surgery should be considered for adults with type 2 diabetes and BMI of 40 kg/m2 or higher, or BMI 35-39.9 kg/m2 with inadequate glycemic control despite lifestyle and optimal medical therapy. Sustained weight loss through any means, whether behavioral, pharmacologic, or surgical, can improve and potentially reverse type 2 diabetes, particularly when achieved earlier in the disease course before significant beta-cell failure.
Diabetes self-management education and support is essential for empowering patients to make informed decisions and implement effective self-care behaviors. Structured education should be provided at diagnosis, annually, when complications develop, and during transitions in care. Core topics include healthy eating, physical activity, blood glucose monitoring, medication management, problem-solving, healthy coping, and reducing risk of complications. A multidisciplinary team including certified diabetes educators, dietitians, and pharmacists optimizes education delivery and ongoing support.
Panel A: Plate method illustration demonstrating optimal meal composition with half plate non-starchy vegetables, quarter plate lean protein, and quarter plate carbohydrate. Panel B: Physical activity recommendations showing target minutes of aerobic activity, resistance training frequency, and importance of reducing sedentary time. Panel C: Graph showing metabolic benefits of progressive weight loss including improvements in A1c, blood pressure, and lipids at 5%, 10%, and 15% weight loss. Panel D: Diabetes self-management education components showing key topics and recommended timing for education interventions.
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### V. Oral Antidiabetic Agents
Metformin remains the preferred first-line pharmacologic agent for type 2 diabetes due to its efficacy, safety profile, low cost, and potential cardiovascular benefits. As a biguanide, metformin works primarily by decreasing hepatic glucose production and secondarily by improving peripheral insulin sensitivity. Typical A1c reduction of 1-1.5% is expected, with additional benefits including weight neutrality or modest weight loss and no intrinsic hypoglycemia risk. Gastrointestinal side effects including nausea, diarrhea, and abdominal discomfort are common but can be minimized by starting at low doses and titrating gradually. Metformin is contraindicated with eGFR below 30 mL/min/1.73m2 and should be temporarily held before and after procedures using iodinated contrast in patients with renal impairment.
SGLT2 inhibitors including empagliflozin, dapagliflozin, and canagliflozin have emerged as important second-line agents, particularly for patients with established cardiovascular disease, heart failure, or chronic kidney disease. These medications lower glucose by inhibiting the sodium-glucose cotransporter-2 in the proximal renal tubule, reducing glucose reabsorption and increasing urinary glucose excretion. Beyond glycemic benefits with A1c reduction of 0.5-1.0%, SGLT2 inhibitors provide cardiovascular and renal protection independent of glucose lowering, reducing heart failure hospitalizations and slowing progression of diabetic kidney disease. Important side effects include genital mycotic infections, urinary tract infections, volume depletion, and rare but serious euglycemic diabetic ketoacidosis.
GLP-1 receptor agonists including semaglutide, liraglutide, dulaglutide, and tirzepatide offer excellent glycemic efficacy with significant weight loss benefits. These agents work by enhancing glucose-dependent insulin secretion, suppressing glucagon, slowing gastric emptying, and promoting satiety through central appetite regulation. A1c reductions of 1-1.8% are typical, with some newer agents achieving even greater efficacy. GLP-1 receptor agonists with proven cardiovascular benefit, including semaglutide and liraglutide, are preferred for patients with established atherosclerotic cardiovascular disease. Gastrointestinal side effects including nausea, vomiting, and diarrhea are common, particularly during initiation, and rare cases of pancreatitis have been reported.
Additional oral agent classes provide options for individualized therapy based on specific patient needs. Sulfonylureas including glipizide, glyburide, and glimepiride are inexpensive and effective but cause weight gain and carry significant hypoglycemia risk, particularly in elderly patients and those with renal impairment. DPP-4 inhibitors including sitagliptin and linagliptin are weight-neutral with low hypoglycemia risk but offer more modest A1c reduction of 0.5-0.8%. Thiazolidinediones including pioglitazone improve insulin sensitivity but cause fluid retention, weight gain, and increased fracture risk. Alpha-glucosidase inhibitors provide modest glycemic benefit by delaying carbohydrate absorption but frequently cause flatulence and gastrointestinal discomfort.
Panel A: Mechanism of action diagram showing how metformin, SGLT2 inhibitors, and GLP-1 receptor agonists work at different target organs. Panel B: Comparative efficacy and side effect profiles of major oral agent classes showing expected A1c reduction, weight effects, and hypoglycemia risk. Panel C: Cardiovascular and renal outcome trial data demonstrating benefits of SGLT2 inhibitors and GLP-1 agonists in high-risk patients. Panel D: Decision algorithm for second-line agent selection based on patient comorbidities including ASCVD, heart failure, and CKD.
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### VI. Insulin Therapy
Insulin therapy is absolutely required for all patients with type 1 diabetes and becomes necessary for many patients with type 2 diabetes as the disease progresses and beta-cell function declines. Type 2 diabetes patients typically require insulin when A1c remains significantly above target (often greater than 10%) despite oral agents, when presenting with symptomatic hyperglycemia or catabolic features, or during intercurrent illness, surgery, or pregnancy. The presence of marked hyperglycemia does not necessarily indicate permanent insulin requirement in type 2 diabetes, as some patients may eventually transition to oral agents after glucose toxicity is resolved. Inpatient settings generally favor insulin therapy for most hospitalized patients with diabetes due to its flexibility and the need to hold many oral agents.
Insulin formulations vary considerably in their pharmacokinetic profiles, affecting how they are used in clinical practice. Rapid-acting insulins including lispro, aspart, and glulisine have onset within 15 minutes, peak at 1-2 hours, and duration of 3-4 hours, making them ideal for mealtime coverage. Short-acting regular insulin has slower onset of 30 minutes with peak at 2-4 hours and duration of 5-8 hours. Intermediate-acting NPH insulin has onset at 2-4 hours, peak at 4-8 hours, and duration of 12-18 hours. Long-acting basal insulins including glargine and detemir provide relatively flat 20-24 hour coverage, while ultra-long-acting degludec offers duration exceeding 42 hours with minimal peak effect.
Insulin regimens can be structured in various ways to meet individual patient needs. Basal-only therapy using once or twice daily long-acting insulin is often the initial approach in type 2 diabetes, providing background insulin coverage while oral agents address mealtime requirements. Basal-bolus regimens combining long-acting insulin with rapid-acting insulin at each meal most closely mimic physiologic insulin secretion and provide maximum flexibility. Premixed insulins containing fixed ratios of intermediate and rapid or short-acting insulin offer convenience but less flexibility for dose adjustments. Sliding scale insulin using only correction doses based on point-of-care glucose without scheduled doses is suboptimal for chronic management but may be appropriate in specific acute situations.
Initiating insulin typically begins with conservative dosing that is subsequently titrated based on glucose patterns. Starting basal insulin doses of 0.1-0.2 units/kg/day or 10 units are common for type 2 diabetes patients beginning insulin therapy. Total daily dose requirements generally range from 0.5-1 unit/kg/day once fully titrated, with basal insulin comprising approximately 40-50% of total daily dose in basal-bolus regimens. Correction factor, often approximated as 1 unit lowering glucose by 50 mg/dL initially, allows adjustment of bolus doses for pre-meal hyperglycemia. Dose titration should occur every 2-3 days for basal insulin, increasing by 10-15% until fasting glucose targets are achieved.
Panel A: Pharmacokinetic profiles of different insulin types showing onset, peak, and duration of action for rapid-acting, short-acting, intermediate-acting, and long-acting formulations. Panel B: Physiologic insulin secretion pattern compared to basal-bolus insulin regimen showing how injections approximate normal patterns. Panel C: Basal insulin titration algorithm showing starting dose, monitoring targets, and adjustment recommendations. Panel D: Sample basal-bolus regimen with timing of injections relative to meals and expected glucose profiles.
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### VII. Treatment Algorithm
Current guidelines recommend a patient-centered approach to type 2 diabetes pharmacotherapy that considers individual comorbidities, preferences, and treatment goals. First-line therapy for most patients remains lifestyle modification combined with metformin, initiated at diagnosis unless contraindications exist. When A1c remains above target after 3 months of metformin monotherapy, selection of second-line therapy should be guided by comorbidities rather than glycemic efficacy alone. The presence of established atherosclerotic cardiovascular disease, heart failure, or chronic kidney disease should drive selection toward agents with proven benefits for these conditions.
For patients with established ASCVD or indicators of high cardiovascular risk, GLP-1 receptor agonists with proven cardiovascular benefit, specifically liraglutide and semaglutide, should be considered as second-line therapy regardless of A1c level. For patients with heart failure, particularly heart failure with reduced ejection fraction, or diabetic kidney disease with albuminuria, SGLT2 inhibitors should be prioritized given their demonstrated benefits in reducing heart failure hospitalizations and slowing CKD progression. When both cardiovascular disease and heart failure or CKD are present, either class may be appropriate, and adding both is reasonable in patients who remain above target on one class.
When compelling indications for specific agent classes do not exist, therapy selection can be individualized based on efficacy, hypoglycemia risk, weight effects, cost, and patient preferences. If minimizing hypoglycemia is a priority, GLP-1 receptor agonists, SGLT2 inhibitors, DPP-4 inhibitors, or thiazolidinediones are preferred over sulfonylureas. When promoting weight loss is important, GLP-1 receptor agonists provide the greatest benefit, followed by SGLT2 inhibitors, while avoiding sulfonylureas and thiazolidinediones which cause weight gain. Cost considerations often favor metformin, sulfonylureas, and thiazolidinediones as generic options, though newer agent classes may become more accessible as generics become available.
Treatment intensification should occur if A1c targets are not achieved after 3-6 months on any given regimen. When multiple oral agents fail to achieve targets, adding basal insulin is typically the next step, though adding GLP-1 receptor agonists to patients not already on this class is an effective alternative. When basal insulin combined with oral agents fails to achieve targets, intensification options include adding prandial insulin (basal-bolus regimen), adding GLP-1 receptor agonist if not already prescribed, or switching to a fixed-ratio combination of basal insulin and GLP-1 agonist. The goal remains simplifying regimens when possible while achieving individualized glycemic targets.
Panel A: ADA/EASD consensus treatment algorithm showing stepwise approach from lifestyle and metformin through second-line and third-line agent selection. Panel B: Decision tree for therapy selection based on comorbidities including ASCVD, heart failure, and CKD with preferred agents for each. Panel C: Cost comparison of different medication classes showing relative costs of branded versus generic options. Panel D: Intensification strategy flowchart showing options when oral agents alone fail to achieve targets.
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### VIII. Acute Complications
Diabetic ketoacidosis represents a potentially life-threatening acute complication occurring predominantly in type 1 diabetes but also possible in type 2 diabetes under certain conditions. DKA is characterized by the triad of hyperglycemia (usually above 250 mg/dL), metabolic acidosis with arterial pH below 7.3 and serum bicarbonate below 18 mEq/L, and ketosis with elevated serum or urine ketones. Precipitating factors include insulin omission or inadequate dosing, infection, myocardial infarction, and other acute illness. Patients present with polyuria, polydipsia, nausea, vomiting, abdominal pain, Kussmaul respirations, fruity breath odor, and progressive altered mental status.
Management of DKA requires aggressive intravenous fluid resuscitation, insulin therapy, potassium replacement, and close monitoring. Initial fluid therapy typically begins with isotonic normal saline at 1-2 liters in the first hour, followed by 250-500 mL per hour adjusted based on hemodynamic status and urine output. Regular insulin is administered as an initial bolus of 0.1 units/kg followed by continuous infusion at 0.1 units/kg/hour, with the goal of steady glucose decline of 50-70 mg/dL per hour. Potassium must be monitored closely and replaced aggressively, as insulin drives potassium intracellularly; if potassium is below 3.3 mEq/L, insulin should be held until potassium is replaced. When glucose reaches 200 mg/dL, dextrose is added to intravenous fluids to allow continued insulin infusion for ketone clearance.
Hyperosmolar hyperglycemic state is a severe hyperglycemic emergency occurring predominantly in elderly patients with type 2 diabetes, characterized by profound hyperglycemia, hyperosmolality, and dehydration without significant ketosis. Glucose levels typically exceed 600 mg/dL and often reach 1000 mg/dL or higher, with serum osmolality above 320 mOsm/kg. Unlike DKA, patients maintain sufficient insulin to prevent lipolysis and ketogenesis, so pH is typically normal or only mildly decreased. HHS has higher mortality than DKA, partly due to the older patient population and greater severity of dehydration and electrolyte abnormalities. Treatment priorities mirror DKA with aggressive fluid resuscitation being paramount, as total body water deficits often exceed 10 liters.
Hypoglycemia remains the limiting factor in achieving tight glycemic control and can result from insulin, sulfonylureas, or other insulin secretagogues. Level 1 hypoglycemia is defined as glucose below 70 mg/dL, level 2 as glucose below 54 mg/dL, and level 3 as severe hypoglycemia requiring assistance from another person for treatment. Symptoms include adrenergic manifestations (tremor, palpitations, sweating, hunger) and neuroglycopenic symptoms (confusion, behavioral changes, seizures, loss of consciousness). Treatment follows the "rule of 15": 15-20 grams of fast-acting carbohydrate, recheck glucose in 15 minutes, and repeat if needed. Severe hypoglycemia requires glucagon administration (intramuscular, subcutaneous, or nasal) or intravenous dextrose when the patient cannot safely swallow.
Panel A: Diagnostic criteria comparison for DKA and HHS showing glucose, pH, bicarbonate, ketones, and osmolality thresholds. Panel B: DKA management flowchart showing fluid resuscitation, insulin infusion, potassium replacement, and monitoring parameters. Panel C: Graph showing the relationship between serum potassium and insulin administration in DKA, demonstrating why potassium must be checked before and during insulin therapy. Panel D: Hypoglycemia treatment algorithm showing symptoms, blood glucose thresholds, and stepwise treatment approach for mild to severe episodes.
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### IX. Chronic Complications
Microvascular complications including retinopathy, nephropathy, and neuropathy result from prolonged hyperglycemia and affect the majority of patients with long-standing diabetes. Diabetic retinopathy is the leading cause of blindness among working-age adults and progresses from mild nonproliferative changes through severe nonproliferative disease to proliferative retinopathy with neovascularization. Screening through dilated fundoscopic examination should begin at diagnosis for type 2 diabetes and within 5 years of diagnosis for type 1 diabetes, with annual follow-up if no retinopathy is present. Treatment includes optimizing glycemic and blood pressure control to slow progression, with laser photocoagulation or anti-VEGF injections for advanced disease.
Diabetic kidney disease affects approximately 40% of patients with diabetes and is the leading cause of end-stage renal disease in the United States. The natural history begins with hyperfiltration, progresses through microalbuminuria (urine albumin 30-300 mg/g creatinine) to macroalbuminuria (above 300 mg/g), and eventually declining GFR and renal failure. Annual screening using both eGFR and urine albumin-to-creatinine ratio should begin at diagnosis for type 2 diabetes and after 5 years for type 1 diabetes. Treatment with ACE inhibitors or ARBs is indicated for patients with albuminuria, SGLT2 inhibitors provide additional renoprotection, and the nonsteroidal mineralocorticoid receptor antagonist finerenone offers further benefit in patients with persistent albuminuria despite RAAS inhibition.
Diabetic neuropathy encompasses multiple clinical syndromes, with distal symmetric polyneuropathy being the most common form. Patients typically present with numbness, tingling, or burning pain in a stocking-glove distribution, progressing from distal to proximal over time. Loss of protective sensation increases risk for foot ulceration, infection, and amputation. Autonomic neuropathy manifests as orthostatic hypotension, resting tachycardia, gastroparesis, erectile dysfunction, and neurogenic bladder. Treatment of painful neuropathy includes gabapentin, pregabalin, duloxetine, and tricyclic antidepressants, while autonomic manifestations are managed symptomatically.
Macrovascular disease, including coronary artery disease, stroke, and peripheral arterial disease, accounts for the majority of mortality in patients with diabetes. Patients with diabetes have 2-4 times higher cardiovascular mortality compared to non-diabetic individuals, and cardiovascular disease often develops at younger ages. Aggressive management of all cardiovascular risk factors, including hypertension, dyslipidemia, smoking cessation, and lifestyle modification, is essential. Statin therapy is recommended for virtually all adults with diabetes aged 40-75 years, with high-intensity statin therapy and additional lipid-lowering agents for those with established ASCVD or very high risk.
Panel A: Fundoscopic images showing progression of diabetic retinopathy from normal through nonproliferative stages to proliferative retinopathy with neovascularization. Panel B: Algorithm for diabetic kidney disease management showing screening, staging, and treatment interventions at each stage. Panel C: Diagram of distal symmetric polyneuropathy distribution pattern with monofilament testing sites for foot examination. Panel D: Cardiovascular risk factor management targets in diabetes showing blood pressure, LDL cholesterol, and antiplatelet therapy recommendations.
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### X. Special Situations
Hospitalized patients with diabetes require special attention to glycemic management, as both hyperglycemia and hypoglycemia are associated with adverse outcomes. Target glucose ranges of 140-180 mg/dL are recommended for most critically ill patients, while non-critically ill patients should have pre-meal glucose targets below 140 mg/dL and random values below 180 mg/dL. Insulin is the preferred agent for most hospitalized patients, with scheduled basal-bolus regimens superior to sliding scale insulin alone. Most oral agents should be held during hospitalization due to concerns about adverse effects in acute illness, though SGLT2 inhibitors may be continued in selected stable patients.
Perioperative management requires careful attention to medication adjustments and glucose monitoring. Oral antidiabetic agents should generally be held the morning of surgery, with metformin held for at least 24 hours postoperatively or until normal renal function is confirmed. Basal insulin doses are typically reduced by 20-50% on the day of surgery to prevent hypoglycemia during the fasting period, while bolus insulin is held when patients are NPO. Intraoperative glucose monitoring allows insulin adjustments to maintain glucose in target range. Once patients resume eating, home medications can be restarted with appropriate adjustments based on nutritional intake and ongoing metabolic status.
Sick day management education is essential for all patients with diabetes, particularly those on insulin. The fundamental rule is never to stop insulin during illness, as stress hormones increase insulin requirements even with decreased oral intake. Blood glucose should be monitored every 2-4 hours, and patients on insulin should check urine or blood ketones if glucose exceeds 250 mg/dL. Adequate hydration is critical, with sugar-free fluids preferred if eating and sugar-containing fluids if unable to eat solid food. Patients should seek medical attention if unable to keep fluids down, if ketones remain elevated, if glucose remains above 300 mg/dL despite extra insulin, or if they develop altered mental status.
Diabetes technology has revolutionized management for many patients, particularly those with type 1 diabetes. Continuous glucose monitors provide real-time glucose values with trend arrows and alerts for hypo- and hyperglycemia, dramatically improving time in range and reducing hypoglycemia. Insulin pump therapy delivers continuous subcutaneous insulin infusion with programmable basal rates and bolus calculators. Automated insulin delivery systems, also called closed-loop or artificial pancreas systems, combine continuous glucose monitoring with insulin pump therapy and control algorithms to automatically adjust insulin delivery based on glucose trends. These technologies are increasingly accessible and appropriate for motivated patients with type 1 diabetes and selected patients with type 2 diabetes on intensive insulin regimens.
Panel A: Hospital glucose management flowchart showing targets and insulin regimen selection for ICU versus non-ICU patients. Panel B: Perioperative medication management table showing which agents to hold, when to hold them, and when to resume. Panel C: Sick day management checklist showing monitoring frequency, ketone testing indications, fluid recommendations, and warning signs requiring medical attention. Panel D: Diabetes technology overview showing continuous glucose monitor, insulin pump, and automated insulin delivery system components with their clinical benefits.
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## Summary
- Type 1 diabetes results from autoimmune beta-cell destruction requiring lifelong insulin; type 2 involves insulin resistance and progressive beta-cell dysfunction
- Diagnosis requires fasting glucose of 126 mg/dL or higher, 2-hour OGTT of 200 mg/dL or higher, A1c of 6.5% or higher, or random glucose of 200 mg/dL or higher with symptoms
- A1c target is less than 7% for most adults but should be individualized based on patient factors including hypoglycemia risk, life expectancy, and comorbidities
- First-line therapy for type 2 diabetes is lifestyle modification plus metformin
- SGLT2 inhibitors are preferred if heart failure or CKD is present; GLP-1 receptor agonists are preferred if ASCVD is present
- Insulin therapy is required for type 1 diabetes and often needed for type 2 diabetes as the disease progresses
- Basal-bolus insulin most closely mimics physiologic secretion; typical total daily dose is 0.5-1 unit/kg
- DKA management requires fluids, insulin, potassium replacement, and monitoring; do not give insulin if potassium is below 3.3 mEq/L
- Microvascular complications (retinopathy, nephropathy, neuropathy) require annual screening and are prevented by good glycemic control
- Sick day rules: never stop insulin, monitor frequently, check ketones if glucose exceeds 250 mg/dL, stay hydrated
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## Key Terms
| Term | Definition |
|------|------------|
| HbA1c | Glycated hemoglobin reflecting average glucose over 2-3 months |
| SGLT2 inhibitor | Sodium-glucose cotransporter 2 inhibitor that increases urinary glucose excretion |
| GLP-1 RA | Glucagon-like peptide-1 receptor agonist that enhances glucose-dependent insulin secretion |
| DKA | Diabetic ketoacidosis; hyperglycemia, acidosis, and ketosis requiring emergent treatment |
| HHS | Hyperosmolar hyperglycemic state; severe hyperglycemia without significant ketosis |
| Time in range | Percentage of time glucose is between 70-180 mg/dL |
| UACR | Urine albumin-to-creatinine ratio used to screen for diabetic kidney disease |
| Basal-bolus | Insulin regimen combining long-acting basal with rapid-acting mealtime insulin |
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*This content is subject to the [MIT License](https://opensource.org/licenses/MIT). © 2024–2026 Hibbert School of Medicine.*