Blood tests for prediabetes and diabetes
For people with prediabetes, type 1 diabetes or type 2 diabetes, and the people who help them keep track of results.
10 tests explainedAI-verified against cited sources. Awaiting expert reviewLast reviewed 2026-10-19
With prediabetes or diabetes, A1c and glucose show how blood sugar is going, but the yearly checks reach further. The ADA suggests regular kidney tests, a lipid panel and a liver scarring score, plus B12 for people who take metformin long term. A1c is useful but not perfect, and a few common conditions can make it read high or low.
The tests that matter most
Most important first. Each one links to its full page, where the note for this group sits near the top.
Hemoglobin A1c (HbA1c)
A1c is an indirect measure of average blood glucose. The ADA suggests checking glucose status at least twice a year, and about every 3 months when goals aren't being met or treatment recently changed. With prediabetes, the ADA suggests testing once a year.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
- Usual adult range
- 4.8–5.6 %
Glucose
Fasting glucose is one of the standard tests for prediabetes and diabetes. In conditions that change how A1c relates to blood glucose, the ADA suggests glucose-based criteria instead of A1c.
- Usual adult range
- 70–99 mg/dL
Urine Albumin/Creatinine Ratio (uACR)
uACR measures albumin, a protein, in urine, which is one way kidney damage shows up. The ADA suggests checking uACR and eGFR at least once a year in everyone with type 2 diabetes and in people who have had type 1 diabetes for 5 years or more. With kidney disease, it suggests checking them 1 to 4 times a year, depending on the stage.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
- Usual adult range
- 0–30 mg/g
eGFR (Creatinine-based)
eGFR estimates how well the kidneys filter, and the ADA pairs it with uACR in those yearly kidney checks. Some diabetes medicines, such as metformin, are used at lower doses or avoided when eGFR is low.
Sources: American Diabetes Association (2026), American Diabetes Association (2026) and American Diabetes Association (2026)
- Usual adult range
- 60 and above mL/min/1.73 m²
LDL Cholesterol
The ADA suggests a lipid panel when diabetes or prediabetes is first found and yearly after that for people not taking cholesterol medicine. When that medicine is started or changed, it suggests a check 4 to 12 weeks later, then yearly.
- Usual adult range
- up to 99 mg/dL
Triglycerides
Diabetes is one of the things that can raise triglycerides. With triglycerides of 150 mg/dL or more, the ADA suggests more focus on lifestyle and glucose management, and when they are very high, it suggests looking for other causes.
- Usual adult range
- up to 149 mg/dL
FIB-4 Index
FIB-4 combines age, ALT, AST and platelets to estimate the chance of liver scarring from fatty liver disease. The ADA suggests it for adults with type 2 diabetes or prediabetes, especially with obesity or other heart and metabolic risk factors, even when liver enzymes are normal. A score of 1.3 or higher leads to a further test, such as a liver stiffness scan.
- 18–64
- up to 1.3 index
- 65+
- up to 2 index
Alanine Aminotransferase (ALT)
ALT is a liver enzyme and one of the inputs to FIB-4. The ADA notes that relying on a raised ALT would miss most people with the inflamed form of fatty liver disease. When ALT stays high for more than 6 months with a low FIB-4, the ADA suggests looking for other liver causes.
- Men, 18+
- 0–44 U/L
- Women, 18+
- 0–32 U/L
Vitamin B12 (Cobalamin)
Metformin is linked to a higher chance of low B12 and to worse nerve symptoms. The ADA suggests periodic B12 testing for people taking metformin, and includes it in the yearly lab list after several years of use.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
- Usual adult range
- 232–1,245 pg/mL
Potassium
Some blood pressure and kidney-protecting medicines can push potassium up, and diuretics can push it down. The ADA suggests checking potassium and eGFR when these medicines are started and periodically after that.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
- Usual adult range
- 3.5–5.2 mmol/L
Ranges shown are the usual adult ranges labs print. The range on your own report is the one your result is judged against.
Getting results you can compare
- The ADA notes that exercise within the past 24 hours, infection, fever, heart failure, very high glucose, menstruation and very high blood pressure can all raise uACR without kidney damage. Because uACR varies so much, two of three tests over 3 to 6 months need to be high before it counts as raised.
- If you use a continuous glucose monitor, its average and your A1c won't always agree. The ADA lists large swings in glucose, measurement error in either device and an inaccurate A1c among the reasons.
Good to know
- A1c can mislead. The ADA lists anemia, iron status, blood loss, transfusion, other changes in red cell turnover, kidney failure, dialysis, cirrhosis, pregnancy and HIV among the things that can change how A1c relates to glucose. Most U.S. A1c tests are accurate in people who carry one copy of a common hemoglobin variant, and with sickle cell trait the ADA advises a test that hemoglobin variants don't affect. A1c can't be measured in sickle cell disease.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
- A1c goals are set person by person. The ADA says a goal below 7% fits many nonpregnant adults, and suggests less strict goals for some older adults, for example those with frailty or complex health, to avoid low blood sugar.
Sources: American Diabetes Association (2026) and American Diabetes Association (2026)
Questions you could ask
- What A1c goal makes sense for me, and why?
- How often should we check my A1c and my kidney tests?
- Would a FIB-4 score be useful in my situation?
- Given how long I've taken metformin, is it time to check my B12?
- Could anything in my health make my A1c less reliable?
Sources
- 2. Diagnosis and Classification of Diabetes: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 4. Comprehensive Medical Evaluation and Assessment of Comorbidities: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 6. Glycemic Goals, Hypoglycemia, and Hyperglycemic Crises: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 10. Cardiovascular Disease and Risk Management: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 11. Chronic Kidney Disease and Risk Management: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
- 13. Older Adults: Standards of Care in Diabetes-2026, American Diabetes Association (2026)
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-19. How we build and check these pages.
Educational information, not medical advice. Blood Test Tracker doesn’t diagnose or treat, and it doesn’t replace your clinician. Talk with your clinician before changing medications, supplements or care.