Diabetes Risk Checker

Diabetes is diagnosed by blood glucose, not symptoms alone

Diabetes isn't diagnosed from how you feel — it's diagnosed by measuring how much glucose (sugar) is circulating in your blood and comparing it against fixed thresholds. There are three standard tests, and this tool sorts your numbers into normal, prediabetes, or diabetes range using the same cutoffs your doctor would use.

• HbA1c: your average blood glucose over the past 2-3 months
• Fasting glucose: blood glucose measured after at least 8 hours without food
• 2-hour glucose (OGTT): blood glucose measured 2 hours after drinking a 75g glucose solution

How to read the screen

Enter whichever values you have on the left — you don't need all three, a routine lab result with just fasting glucose or just HbA1c is enough. The right side shows your overall category in large text, and the risk scale below it marks exactly where each value sits between normal, prediabetes, and diabetes range. A per-test breakdown appears alongside the overall result.

The 3 tests and U.S. (ADA) diagnostic criteria

Each test has its own cutoffs for normal, prediabetes, and diabetes range under ADA guidelines. For example, an HbA1c of 5.9% and a fasting glucose of 108 mg/dL both fall in the prediabetes band, so the overall result is prediabetes even if the 2-hour glucose (150 mg/dL, also prediabetes range here) agrees. If any single test crosses into the diabetes range, the overall result is diabetes range.

• HbA1c: below 5.7% normal / 5.7-6.4% prediabetes / 6.5% or higher diabetes range
• Fasting glucose: below 100 mg/dL normal / 100-125 mg/dL prediabetes (IFG) / 126 mg/dL or higher diabetes range
• 2-hour glucose (OGTT): below 140 mg/dL normal / 140-199 mg/dL prediabetes (IGT) / 200 mg/dL or higher diabetes range

What HbA1c actually measures

HbA1c reflects the percentage of hemoglobin in your red blood cells that has glucose attached to it, which builds up and clears over the roughly 2-3 month lifespan of a red blood cell. That makes it a rolling average of your blood glucose rather than a single-moment snapshot, so it's less affected by what you ate that morning. U.S. labs report HbA1c using the standardized NGSP method. Conditions that affect red blood cells — anemia, recent transfusion, certain hemoglobin variants — can skew the result.

Fasting glucose vs. the 2-hour OGTT

Fasting glucose measures how well your body controls blood sugar at rest, after at least 8 hours without food. The 2-hour oral glucose tolerance test (OGTT) measures how well your body clears a glucose load — you drink a 75g glucose solution and get tested 2 hours later. Some people have normal fasting glucose but an abnormal 2-hour reading, sometimes called isolated post-load hyperglycemia; running both tests catches more cases than either alone.

Why the highest category wins

HbA1c, fasting glucose, and the 2-hour OGTT each look at glucose control from a different angle and at a different point in time. If any one of them crosses into the diabetes range, that's treated as a signal something is off with glucose regulation, even if the other tests look normal. That's why this tool — like standard clinical practice — classifies you by whichever test places you in the highest category, and why an abnormal result is usually confirmed with a repeat test on another day.

What prediabetes means — and why it's often reversible

Prediabetes means your glucose is higher than normal but not yet in the diabetes range. Left unaddressed, a large share of people with prediabetes go on to develop type 2 diabetes within several years. The encouraging side: prediabetes is the stage where lifestyle changes have the best odds of bringing glucose back to normal.

• Losing just 5-7% of body weight meaningfully lowers risk
• At least 150 minutes a week of moderate aerobic activity, plus strength training
• Cutting back on refined carbs, added sugar, and sugary drinks
• Repeat glucose testing every 3-6 months to track progress

Normal today doesn't mean risk-free forever

A normal result today isn't a permanent guarantee, especially if you have risk factors that raise your odds of glucose rising over time. If you have a family history of diabetes, carry excess weight (especially around the abdomen), have high blood pressure or abnormal cholesterol, are inactive, had gestational diabetes, or are over 45, keep getting checked regularly even with normal numbers. See a doctor regardless of your numbers if you notice excessive thirst, frequent urination, or unexplained weight loss.

Common mistakes that throw off your result

Blood glucose isn't a fixed number — it shifts with how and when you measure it. Feeding the wrong conditions into this tool will give you a misleading category.

• Fasting glucose must be measured after at least 8 hours without food (water is fine)
• Illness, infection, stress, and poor sleep can temporarily raise glucose
• Home glucose meter readings can differ from a lab venous blood draw
• HbA1c can be inaccurate with anemia, recent blood transfusion, or during pregnancy

Before you check your result

To trust the category this tool gives you, confirm your inputs were measured under the right conditions. Run through this checklist, and if you land in prediabetes or diabetes range, schedule a follow-up test and a conversation with a doctor.

• Are these numbers from a recent lab test, ideally a venous blood draw?
• Was fasting glucose measured after at least 8 hours without food?
• Is your HbA1c reported as a percentage (NGSP)?
• Is your glucose in mg/dL? (If it's in mmol/L, multiply by 18 to convert.)
• If you land in prediabetes or diabetes range, have you scheduled a follow-up visit?