The hemoglobin A1c test is most reliable for adults. Some experts recommend using one of the other tests to diagnose diabetes in children.footnote 2 This test may not be right for everyone. That's because many things can affect the lifespan of red blood cells, such as the second or third trimester of pregnancy, a recent blood loss or a blood transfusion, sickle cell disease, hemodialysis, or erythropoietin (ESA) medicine.
Two tests are used to confirm the diagnosis of diabetes.
Criteria for prediabetes
You may be diagnosed with prediabetes if your blood sugar is above normal but not high enough to be diabetes. You have prediabetes if you meet one of the following criteria:footnote 1
Your fasting blood sugar test results are between 6.1 mmol/L and 6.9 mmol/L.
Your OGTT result is between 7.8 mmol/L and 11.0 mmol/L (2 hours after you start the test).
Your hemoglobin A1c result is 6.0% to 6.4%.
Ask your doctor how often you need to be tested.
Other possible tests
It may be hard to tell what type of diabetes you have. If so, your doctor may do a C-peptide test or test for autoantibodies to diagnose type 1 diabetes or a slowly developing form of type 1 diabetes called latent autoimmune diabetes in adults (LADA). Some rare forms of diabetes are caused by a genetic problem. You may need genetic testing to diagnose them. This includes maturity onset diabetes of the young (MODY). There are many types of MODY, depending on the gene that is affected.
Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Definition, classification and diagnosis of diabetes, prediabetes and metabolic syndrome. Canadian Journal of Diabetes, 42(Suppl 1): S10–S15. DOI: 10.1016/j.jcjd.2017.10.003. Accessed October 15, 2018.
Diabetes Canada Clinical Practice Guidelines Expert Committee, et al. (2018). Type 2 diabetes in children and adolescents. Canadian Journal of Diabetes, 42(Suppl 1): S247–S254. DOI: 10.1016/j.jcjd.2017.10.037. Accessed October 15, 2018.
Current as of:
March 1, 2023
Author: Healthwise Staff Medical Review: E. Gregory Thompson MD - Internal Medicine Kathleen Romito MD - Family Medicine Adam Husney MD - Family Medicine Matthew I. Kim MD - Endocrinology David C.W. Lau MD, PhD, FRCPC - Endocrinology
Medical Review:E. Gregory Thompson MD - Internal Medicine & Kathleen Romito MD - Family Medicine & Adam Husney MD - Family Medicine & Matthew I. Kim MD - Endocrinology & David C.W. Lau MD, PhD, FRCPC - Endocrinology
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