Diabetes testing uses HbA1c, fasting glucose, and OGTT thresholds to diagnose diabetes and prediabetes. Screen people with risk factors and monitor diagnosed patients with regular A1c, urine albumin-to-creatinine, lipids, eye and foot checks. Home glucose meters and continuous glucose monitors support daily management. Guidelines for screening age and gestational testing approaches vary - verify current society recommendations.

Why testing matters

Diabetes is a metabolic disorder caused by insufficient insulin action. Early detection limits organ damage (eyes, kidneys, heart, nerves) and allows timely treatment and lifestyle change. Testing is recommended for people at risk and for routine monitoring of those with known diabetes.

Who should be screened

Routine screening is advised for adults with risk factors (overweight/obesity, family history, prior gestational diabetes, certain racial/ethnic groups, hypertension, or dyslipidemia). Children and adolescents with risk factors should also be tested. Screening recommendations vary by age and organization - check the current ADA/USPSTF guidance for exact age thresholds.

Common signs that prompt testing

  • Increased thirst and urination
  • Unexplained weight loss or increased hunger
  • Recurrent infections or slow-healing wounds
  • Fatigue, blurred vision
  • Episodes of hypoglycemia in treated patients
Presence of these signs with high random glucose levels supports a diagnosis.

How diabetes is diagnosed (standard laboratory tests)

  • Hemoglobin A1c (HbA1c): diabetes if ≥6.5%; prediabetes 5.7-6.4%.
  • Fasting plasma glucose (FPG): diabetes if ≥126 mg/dL; prediabetes 100-125 mg/dL.
  • 2-hour plasma glucose during a 75 g oral glucose tolerance test (OGTT): diabetes if ≥200 mg/dL; prediabetes 140-199 mg/dL.
  • Random plasma glucose ≥200 mg/dL with classic symptoms also meets diagnostic criteria.
Clinicians use one or more of these tests to confirm diagnosis and to assess risk of progression.

Testing in pregnancy

Pregnant people are screened for gestational diabetes, commonly between 24-28 weeks. Guidelines differ: many programs use a one-step 75 g OGTT; others use a two-step approach (50 g screen followed by a 100 g diagnostic OGTT). Check current obstetric society recommendations for the preferred method. 1

Home monitoring and continuous glucose

Capillary blood glucose meters remain useful for daily checks, dose adjustments, and hypoglycemia detection. Continuous glucose monitoring (CGM) devices provide real-time trends and are increasingly used for type 1 diabetes and many with type 2 diabetes on insulin. Home urine glucose testing is not recommended for diagnosis.

Ongoing monitoring and complication screening

  • HbA1c: typically every 3 months if therapy or control changes; every 6 months if stable and at goal.
  • Kidney: annual urine albumin-to-creatinine ratio (UACR); UACR ≥30 mg/g indicates abnormal albuminuria.
  • Lipids: periodic fasting or nonfasting lipid panels to assess cardiovascular risk.
  • Blood pressure: regular measurement and control to reduce complications.
  • Eyes: baseline and at least annual dilated retinal exams per risk.
  • Feet: regular inspection for neuropathy and circulation problems.

Practical notes

Bring fasting or random test instructions from your clinic. For home meters and CGMs, follow manufacturer calibration and record-keeping advice. Regular testing and follow-up reduce complication risks and guide treatment choices.
  1. Confirm current age-based screening recommendations from ADA/USPSTF (2025)
  2. Verify preferred gestational diabetes screening approach per current ACOG/ADA guidance (2025)

FAQs about Diabetes Testing

What A1c level diagnoses diabetes?
An HbA1c of 6.5% or higher on a validated test indicates diabetes; 5.7-6.4% is considered prediabetes.
Can I diagnose diabetes with a home glucose meter?
No. Home meters are for daily management. Diagnosis should rely on laboratory plasma glucose or laboratory-validated A1c measurements.
How often should someone with diabetes get an A1c test?
Typically every 3 months when starting or changing therapy, and every 6 months if glycemic control is stable and at target.
What test is used to screen for kidney damage?
An annual urine albumin-to-creatinine ratio (UACR) screens for early diabetic kidney disease; a UACR ≥30 mg/g is abnormal.
How is gestational diabetes screened?
Pregnant people are usually screened between 24-28 weeks. Some places use a one-step 75 g OGTT; others use a two-step 50 g screen with a diagnostic 100 g OGTT. Local obstetric guidance determines the approach.

News about Diabetes Testing

Sick Day Guidelines for Type 1 Diabetes - Everyday Health [Visit Site | Read More]

At least 55,000 people face new tests in diabetes error - BBC [Visit Site | Read More]

Neonatal hypoglycemia screening practices in infants born to mothers without glucose tolerance testing - Nature [Visit Site | Read More]

Cambridge company creates app for quick type 2 diabetes test - BBC [Visit Site | Read More]

NHS Highland and Digostics launch world-first home diabetes screening for patients with cystic fibrosis - NHS Highland [Visit Site | Read More]

Postpartum diabetes screening for women with gestational diabetes in Japan: an administrative database study - BMJ Open [Visit Site | Read More]

Hidden genetic risk could delay diabetes diagnosis for Black and Asian men - University of Exeter [Visit Site | Read More]