Written with men in mind. Most of this guide applies to everyone. Details specific to women — such as screening ages and risks that differ — are not covered yet; female health guides are being written.
What it is
In type 2 diabetes, the body doesn't make enough insulin or doesn't use it well, so sugar (glucose) builds up in the blood. Over time, high blood sugar can damage the heart, blood vessels, nerves, eyes and kidneys.[1] Prediabetes means blood sugar is higher than normal but not yet in the diabetes range.[2]
Insulin is made by the islet cells of the pancreas and lets cells take up glucose. Type 2 diabetes involves insulin resistance plus inadequate insulin secretion. It is diagnosed with blood tests such as the A1C (average glucose over about 3 months) or fasting plasma glucose.[1][3]
Diagnostic thresholds and test choice are described by NIDDK; screening in adults 35–70 with overweight or obesity is a USPSTF grade B recommendation, with a BMI cut-off of 23 suggested for Asian American adults.[3][2] Microvascular (retinopathy, nephropathy, neuropathy) and macrovascular complications drive morbidity.[1]
See the pancreas, which makes insulin, tucked behind the stomach.
See it in 3DHow common it is
Causes and risk factors
Things you can't change
- Age 35 or older.[5]
- A family history of diabetes.[5]
- Being African American, American Indian, Asian American, Hispanic/Latino or Pacific Islander.[5]
Things you can change
Symptoms worth reporting to a doctor
- Urinating more often
- Feeling very thirsty
- Feeling very hungry, even after eating
- Blurred vision
- Tiredness
- Sores that don't heal
- Frequent infections, such as urinary tract or skin infections
Symptoms can develop slowly over several years. Many people have no symptoms, or symptoms so mild they don't notice them.[6]
Screening: who, when and how
USPSTF recommends screening for prediabetes and type 2 diabetes in adults aged 35 to 70 who have overweight (BMI 25 or more) or obesity (BMI 30 or more) (grade B). A lower BMI cut-off of 23 may be appropriate for Asian American adults.[2]
How it's diagnosed
Types of treatment
- Healthy eating and activity. Planning healthy meals, staying active and limiting calories if you're overweight are key parts of care.[1]
- Medicines. Pills or injected medicines, which may include insulin. Some newer diabetes medicines are also used to lower heart risk.[1][7]
- Managing related risks. Keeping blood pressure and cholesterol in check and quitting smoking, because untreated diabetes can lead to heart disease, stroke, and nerve, kidney, eye and foot problems.[1]
Which option fits depends on the details of each person’s situation. Your care team decides with you.
What you can do
Be active
Losing weight and being more physically active may prevent or delay type 2 diabetes.[5]
Small, steady changes
Swap sugary drinks for water and build meals around vegetables, whole grains and lean protein.[1]
Protect your sleep
Part of heart-healthy living, which also lowers diabetes-related heart risk.[7]
Questions to ask your doctor
- What is my A1C, and what does it mean?
- Do I have prediabetes? How can I stop it progressing?
- Which medicine is best for me, and does it also protect my heart or kidneys?
- How often should my eyes, feet and kidneys be checked?
Myth vs. fact
Related topics
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Sources
- NIH National Institute of Diabetes and Digestive and Kidney Diseases. Type 2 Diabetes. Checked 23 October 2026.
- US Preventive Services Task Force. Prediabetes and Type 2 Diabetes: Screening (August 2021). Checked 23 October 2026.
- NIH National Institute of Diabetes and Digestive and Kidney Diseases. Diabetes Tests & Diagnosis. Checked 23 October 2026.
- Centers for Disease Control and Prevention. National Diabetes Statistics Report. Checked 23 October 2026.
- NIH National Institute of Diabetes and Digestive and Kidney Diseases. Risk Factors for Type 2 Diabetes. Checked 23 October 2026.
- NIH National Institute of Diabetes and Digestive and Kidney Diseases. Symptoms & Causes of Diabetes. Checked 23 October 2026.
- NIH National Heart, Lung, and Blood Institute. Coronary Heart Disease: Treatment. Checked 23 October 2026.
The owner of this website is not a doctor. Human Atlas provides educational anatomy information and does not diagnose, stage, or treat disease. Talk to a qualified clinician about anything concerning your own health.