Understanding type 2 diabetes

What happens in your body with type 2 diabetes, how it's diagnosed, why it isn't your fault, and why looking after your blood sugar, blood pressure and cholesterol protects your health.

6 min read · last reviewed October 3, 2026

If you've just been told you have type 2 diabetes, you're in good company. Millions of people around the world live with it, and many of them live long, active lives. Understanding what's going on in your body is a great first step. It helps the rest of your plan make sense.

What happens in type 2 diabetes?

When you eat, your body breaks down carbohydrates into a sugar called glucose. Glucose travels in your blood to your cells, where it's used for energy.

To get into most cells, glucose needs help from insulin, a hormone made by the pancreas, a small organ behind your stomach. Think of insulin as a key that unlocks your cells so glucose can get in.

In type 2 diabetes, two things happen:

1. The locks get "sticky." Your muscle, liver and fat cells don't respond to insulin as well as they should. This is called insulin resistance.
2. The key-maker gets tired. At first, the pancreas makes extra insulin to keep up. Over time, it often can't keep up, and insulin levels aren't enough.

Your liver also tends to release more glucose into your blood than you need, especially overnight. Together, these changes cause blood sugar to rise.

Symptoms: often none at first

Type 2 diabetes usually develops slowly, over years. Many people feel fine and are diagnosed through a routine blood test. When symptoms do happen, they may include:

• feeling very thirsty, or peeing more than usual
• feeling tired
• blurry vision
• infections that keep coming back, such as yeast or bladder infections
• cuts or sores that heal slowly
• tingling or numbness in the hands or feet

Something you can do today: If you've had any of these symptoms, tell your team, and notice if they improve as your blood sugar comes down.

How is it diagnosed?

Diabetes Canada and the American Diabetes Association use similar blood tests. Diabetes is usually diagnosed if you have one of these, and in most cases a second test confirms it:

• A1C (your average blood sugar over 2 to 3 months) of 6.5% or higher
• Fasting blood sugar (after at least 8 hours without food) of 7.0 mmol/L (126 mg/dL) or higher
• A 2-hour glucose drink test (oral glucose tolerance test) result of 11.1 mmol/L (200 mg/dL) or higher
• A random blood sugar of 11.1 mmol/L (200 mg/dL) or higher with symptoms of diabetes

Why did this happen to me?

Type 2 diabetes is not your fault. It comes from a mix of things, many outside your control:

• Family history and genes. Type 2 diabetes runs strongly in families.
• Age. Risk goes up as we get older, although more young people are being diagnosed too.
• Ethnic background. It's more common in people of South Asian, Asian, African, Caribbean, Hispanic and Indigenous descent.
• Body weight, especially around the belly. This is linked to insulin resistance, and weight itself is shaped by genes, stress, sleep, medicines, money and environment.
• Other conditions and medicines. Such as having had diabetes in pregnancy, polycystic ovary syndrome, high blood pressure, or taking steroid medicines.
• Life circumstances. Stress, shift work, poor sleep and limited access to healthy food or safe places to be active all play a part.

Why it matters, and why there's hope

Over many years, high blood sugar can damage blood vessels and nerves. This can affect your:

• heart and blood vessels (heart attack and stroke)
• kidneys
• eyes (retinopathy)
• nerves, especially in the feet

That might sound frightening, but here's the hopeful part: you can lower these risks a lot. Keeping blood sugar, blood pressure and cholesterol close to your targets, not smoking, staying active and having regular checkups all help. Some newer diabetes medicines also protect the heart and kidneys directly.

What are my targets?

Your team will set targets that are right for you. As a guide, Diabetes Canada suggests many adults aim for:

• an A1C of 7.0% or lower
• blood sugar of 4.0 to 7.0 mmol/L (about 70 to 126 mg/dL) before meals
• blood sugar of 5.0 to 10.0 mmol/L (about 90 to 180 mg/dL) 2 hours after meals
• blood pressure below 130/80

Your targets may be higher if you're older, have other health problems or have had serious lows, or lower in some situations. Ask, "What targets are right for me?"

Type 2 diabetes can change over time

For many people, the pancreas slowly makes less insulin over the years. That means you may need more or different medicines over time, even if you're doing everything "right." This is the natural course of the condition, not a sign you've failed.

For some people, especially soon after diagnosis, substantial weight loss can bring blood sugar back to a normal range without medicines. This is called remission. Read Type 2 diabetes treatment options to learn more.

Something you can do this week: Ask your team to explain your A1C result and write down your target.

Questions to ask your care team

• How sure are we that I have type 2 diabetes, and not another type?
• What was my A1C? What should my targets be?
• Do I have any signs of complications yet?
• What can my family do to lower their own risk?
• How will we know if my treatment is working?

This article is general information, not medical advice. Talk with your health care team about your own situation. In an emergency, call 9-1-1 or your local emergency number.

In an emergency, call 9-1-1 or your local emergency number.

General information, not medical advice. It does not replace your own care team. If you think you or someone else is having a medical emergency, call 9-1-1 or your local emergency number. If you are in crisis or thinking about suicide, call or text 9-8-8 (Canada and the US).

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