- Type 2 diabetes develops from a mix of risk factors. Some you cannot change, such as age and family history. Many you can, such as weight, activity, sleep and diet.
- Risk climbs steeply with age and with extra body weight.
- Among people at high risk, modest lifestyle changes cut the chance of developing diabetes by more than half in a landmark trial.
No single thing causes type 2 diabetes. It builds up from several risk factors that add together over years, mostly by making the body more resistant to insulin or by putting extra strain on the pancreas. Knowing your own risk factors tells you two useful things: whether you should be tested, and where your efforts will make the biggest difference.
If you already have prediabetes, many of these points will be familiar from Lifestyle Risk Factors for Prediabetes. This article focuses on type 2 diabetes itself and on the risk factors that are easy to overlook.
Risk factors you cannot change
Risk rises with every decade, especially after 35–45, as muscle mass falls and insulin sensitivity declines.
Having a parent or sibling with type 2 diabetes raises your risk. Families share genes and often habits too.
People of South Asian, Black African or Caribbean, Hispanic, Indigenous and some East Asian and Pacific Islander backgrounds develop it more often, often at a younger age and lower body weight.
Gestational diabetes, or having a baby weighing over 9 lb (4 kg), raises a woman’s lifetime risk. So does polycystic ovary syndrome (PCOS).
How much does age and weight matter?
A lot. United States survey data show how steeply the share of adults with diabetes (diagnosed or not) climbs with age and weight:
Adults with diabetes, United States, 2021–2023
Source: CDC National Center for Health Statistics, Data Brief 516 (2024).
Risk factors you can change
These are where your effort pays off. They all work through the same basic mechanism: they make your muscles and liver more or less sensitive to insulin.
Fat stored inside the abdomen and liver drives insulin resistance more than fat elsewhere. A growing waist is an early warning sign.
Working muscles take up glucose even without much insulin. Being active fewer than three times a week raises risk.
Sugary drinks, refined grains and processed meat raise risk. Fiber, whole grains, legumes, nuts and vegetables lower it.
Regularly sleeping less than about 6 hours, or untreated sleep apnea, makes the body less sensitive to insulin.
Smokers are 30–40% more likely to develop type 2 diabetes than non-smokers.
Long-term stress hormones raise blood sugar and make healthy routines harder to keep.
Health conditions that raise your risk
Some conditions travel with type 2 diabetes because they share the same root cause, insulin resistance. If you have any of these, ask about a diabetes test:
- Prediabetes, the strongest single predictor.
- High blood pressure or abnormal cholesterol (low HDL, high triglycerides). See Metabolic Syndrome: The 5 Numbers That Matter.
- Fatty liver disease (now called MASLD).
- Heart disease or a history of stroke.
- Darkened, velvety skin on the neck or armpits (acanthosis nigricans), a visible sign of insulin resistance.
- Long-term use of certain medicines, such as steroids, some antipsychotics, and some HIV medicines.
The good news: risk can be lowered
The US Diabetes Prevention Program followed over 3,000 adults with overweight and raised blood sugar. Those who aimed for about 7% weight loss and 150 minutes of brisk activity a week cut their risk of developing type 2 diabetes by 58% over about three years, compared with those given standard advice. The effect was even larger, 71%, in people over 60.
Diabetes Prevention Program Research Group, NEJM 2002.
You do not need to change everything at once. The most useful first steps are usually a daily walk, swapping sugary drinks for water, adding vegetables and legumes to meals, and protecting your sleep. Our 6 Steps to Improve Prediabetes gives a practical weekly plan.
Should you be tested?
The American Diabetes Association recommends testing all adults from age 35, and earlier for adults with overweight or obesity who have at least one other risk factor above. If your results are normal, repeat the test at least every three years. People with prediabetes should be tested every year.
Check your risk in two minutes. Try our Diabetes Risk Check, then take the result to your next appointment.
Common questions
I have a strong family history. Is diabetes inevitable?
No. A family history raises your risk, but it does not seal your fate. In the Diabetes Prevention Program, lifestyle changes cut risk substantially regardless of family history. Knowing your history is a reason to be tested earlier and more often, and to start protective habits now.
How much weight do I need to lose to lower my risk?
Less than most people think. Losing about 5–7% of body weight, for example 5–7 kg (11–15 lb) for someone weighing 100 kg (220 lb), improved insulin sensitivity enough to more than halve diabetes risk in the Diabetes Prevention Program. Even without weight loss, regular activity improves how your muscles use glucose.
- Age, family history, ethnicity and pregnancy history raise risk but cannot be changed.
- Waist size, activity, diet, sleep and smoking can be changed, and they matter a lot.
- Lifestyle changes cut the risk of type 2 diabetes by more than half in people at high risk.
- Next: Early signs and symptoms of type 2 diabetes.
Type 2 Diabetes Basics: all 18 articles
- What Is Type 2 Diabetes?
- Type 2 Diabetes Risk Factors
- Early Signs and Symptoms
- How Type 2 Diabetes Is Diagnosed
- A1C vs Blood Glucose
- Diabetes and Your Heart
- Preventing Long-Term Complications
- Type 2 Diabetes Medicines Explained
- GLP-1 Medicines: What to Expect
- Taking Your Medicines Consistently
- When Your Diabetes Changes
- Digital Tools: Meters, CGMs and Apps
- How to Read a Nutrition Label
- Carb Counting Made Simple
- Small Food Swaps for Lower Blood Sugar
- Travelling With Diabetes
- Diabetes Distress and Depression
- Caring for Someone With Type 2 Diabetes
Sources
- Diabetes Prevention Program Research Group; Knowler WC, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346:393–403.
- National Center for Health Statistics, CDC. Prevalence of total, diagnosed, and undiagnosed diabetes in adults: United States, August 2021–August 2023. NCHS Data Brief No. 516; 2024.
- Centers for Disease Control and Prevention. Diabetes Risk Factors. 2024.
- American Diabetes Association Professional Practice Committee. Standards of Care in Diabetes—2026, Section 2: Diagnosis and Classification. Diabetes Care. 2026;49(Suppl 1).
- US Preventive Services Task Force. Screening for prediabetes and type 2 diabetes: recommendation statement. JAMA. 2021;326(8):736–743.
- US Department of Health and Human Services. The Health Consequences of Smoking—50 Years of Progress: A Report of the Surgeon General. 2014.
This article is for general education and is not a substitute for advice from your own doctor, diabetes educator or pharmacist.