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Glucose unit converter and interpretation

Convert glucose units and HbA1c (% ↔ mmol/mol). Get fasting / OGTT / random / HbA1c interpretation under ADA 2024 — normal, prediabetes, diabetes ranges.

Last updated: Sources verified:

What this calculator does

Two functions in one tool:

  1. Unit conversion — between mg/dL and mmol/L for plasma glucose, and between % and mmol/mol for HbA1c.
  2. ADA 2024 interpretation — applies the diagnostic thresholds for normal / prediabetes / diabetes to a fasting glucose, 2-hour OGTT, random glucose, or HbA1c value.

You pick the test type, enter your value in either unit, and the calculator returns both unit forms plus the interpretation band with rich next-step guidance.

Conversions

Glucose: 1 mmol/L = 18.0182 mg/dL HbA1c: IFCC (mmol/mol) = (NGSP % − 2.15) × 10.929

ADA 2024 diagnostic thresholds

TestNormalPrediabetesDiabetes
Fasting plasma glucose< 100 mg/dL (5.6 mmol/L)100–125 mg/dL (5.6–6.9 mmol/L)≥ 126 mg/dL (7.0 mmol/L)
2h OGTT (75 g)< 140 mg/dL (7.8 mmol/L)140–199 mg/dL (7.8–11.0 mmol/L)≥ 200 mg/dL (11.1 mmol/L)
Random glucose + symptoms——≥ 200 mg/dL (11.1 mmol/L)
HbA1c< 5.7% (39 mmol/mol)5.7–6.4% (39–46 mmol/mol)≥ 6.5% (48 mmol/mol)

A single abnormal value typically warrants a confirmation test on a different day. Random glucose ≥ 200 mg/dL with classic symptoms (polyuria, polydipsia, unexplained weight loss) is itself diagnostic per ADA.

Why catch glucose dysregulation early

Type 2 diabetes typically develops over years of slowly rising glucose. Most of the irreversible complications (kidney disease, retinopathy, cardiovascular events) accumulate after years of poorly controlled glucose. The earliest stages — prediabetes and the first 1–2 years of diabetes — are when intervention most preserves beta-cell function and most reduces lifetime complications.

The Diabetes Prevention Program (Knowler 2002) and the Finnish DPS showed that structured lifestyle change reduces diabetes incidence by ~58% over 3 years in people with prediabetes. Metformin in selected populations adds additional protection.

Privacy

All calculations run entirely in your browser. We never see, log, or store your individual values. Only an anonymous event is sent to a privacy-respecting analytics service.

Frequently asked questions

How do mg/dL and mmol/L relate?
They measure the same thing — glucose concentration in blood — in different units. The conversion factor is 18.0182. To convert mg/dL to mmol/L, divide by 18; to convert mmol/L to mg/dL, multiply by 18. United States, Germany, and Japan typically report in mg/dL; United Kingdom, Australia, and most of Europe in mmol/L. Both units are equivalent in clinical meaning.
What is HbA1c, and why two units?
HbA1c (glycated haemoglobin) reflects the average blood glucose over the past ~3 months. It is reported in two parallel systems: NGSP percentage (%) used in the US and most clinical communication, and IFCC mmol/mol used as the international standard. Conversion: IFCC = (% − 2.15) × 10.929. So HbA1c 6.5% (the diabetes threshold) ≈ 48 mmol/mol.
What are the ADA 2024 thresholds for diabetes?
Diabetes is diagnosed when one of: fasting plasma glucose ≥ 126 mg/dL (7.0 mmol/L); 2-hour OGTT ≥ 200 mg/dL (11.1 mmol/L); HbA1c ≥ 6.5% (48 mmol/mol); or a random glucose ≥ 200 mg/dL (11.1 mmol/L) with classic symptoms (polyuria, polydipsia, unexplained weight loss). Without symptoms, two abnormal results from the same or different tests are typically required to confirm.
What does prediabetes mean?
Prediabetes refers to glucose values higher than normal but below diabetes thresholds — fasting 100–125 mg/dL (5.6–6.9 mmol/L), OGTT 140–199 mg/dL (7.8–11.0 mmol/L), or HbA1c 5.7–6.4% (39–46 mmol/mol). It is the most reversible stage of glucose dysregulation. The Diabetes Prevention Program showed structured lifestyle change reduces progression to type 2 diabetes by ~58% over 3 years.
Should I worry about a single elevated value?
Single values vary 3–5% between assays, and stress, illness, or recent exercise can transiently shift glucose by 10–20 mg/dL. ADA criteria require either two abnormal tests at different times or one elevated value plus classic symptoms before a definitive diabetes diagnosis. If your value is borderline, your doctor will typically order a confirmation test (often a different one — e.g., HbA1c after a fasting glucose) before any label.
Does this calculator replace blood-test interpretation?
No. It applies ADA 2024 thresholds to a value you already have to give context — but interpreting in the full clinical picture (medications, recent illness, family history, comorbidities) is the job of a healthcare professional. If your value sits in the prediabetes or diabetes range, contact your primary-care provider for confirmation testing and a care plan.
Does my data leave the device?
No. All calculations run entirely in your browser. Only an anonymous event (locale, test type, band) is sent to a privacy-respecting analytics service. Your individual values never leave the device.

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Sources

  1. Standards of Care in Diabetes — 2024 — American Diabetes Association (ADA, 2024) (guideline, retrieved 2026-04-30)
  2. IDF Diabetes Atlas, 10th edition — International Diabetes Federation (IDF, 2021) (guideline, retrieved 2026-04-30)
  3. Reduction in the Incidence of Type 2 Diabetes With Lifestyle Intervention or Metformin (DPP) — N Engl J Med (Knowler et al., 2002) (peer reviewed, retrieved 2026-04-30)