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OGTT Calculator
Enter glucose (mg/dL) and insulin (µU/mL) at each timepoint. Fasting (0 min) values are required; 30/60/90/120 min values are used for the Matsuda ISI.
Please enter fasting (0 min) glucose and insulin, and at least glucose/insulin for the remaining timepoints you want included.
| Time (min) | Glucose (mg/dL) | Insulin (µU/mL) |
|---|---|---|
| 0 (required) | ||
| 30 | ||
| 60 | ||
| 90 | ||
| 120 |
Fasting Insulin × Fasting Glucose (I0 × G0)
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I0 (µU/mL) × G0 (mg/dL)
Reference (approximate, same scale as HOMA-IR ×405): <405 optimal · 405–770 mild · 770–1175 significant · >1175 high
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HOMA-IR
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(G0 × I0) ÷ 405
Commonly cited reference: <1.0 optimal · 1.0–1.9 mild insulin resistance · 1.9–2.9 significant · >2.9 high
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ISI (Matsuda Index)
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10,000 ÷ √[(G0×I0) × (mean G × mean I)], using all timepoints entered
Commonly cited reference (higher = more insulin sensitive): <2.5 insulin resistant · 2.5–4.0 reduced sensitivity · >4.0 normal/good sensitivity
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This tool performs standard OGTT-derived calculations (HOMA-IR, Matsuda ISI) for reference purposes and does not constitute medical advice or a diagnosis. Formulas assume glucose in mg/dL and insulin in µU/mL. The reference ranges shown are commonly cited cutoffs from the literature, but they are not universally standardized — they vary by lab, insulin assay method, and population studied, and are not diagnostic thresholds on their own. Results should be interpreted by a qualified clinician alongside the full clinical picture.
Free Testosterone Calculator
Estimates free testosterone from total testosterone, SHBG, and albumin using the Vermeulen equation.
Please enter a sex, total testosterone, and SHBG. Albumin will default to 4.3 g/dL if left blank.
Free Testosterone
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Vermeulen equation: quadratic solution of the testosterone / SHBG / albumin mass-action equilibrium (Ka = 3.6×10&sup4; L/mol, Kt = 5.97×10&sup8; L/mol)
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Free Testosterone, % of Total
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Free T ÷ Total T × 100. Typically ~1–3% in adults, roughly independent of total T level.
This tool estimates calculated free testosterone using the Vermeulen equation (Vermeulen A, Verdonck L, Kaufman JM. J Clin Endocrinol Metab. 1999) and does not constitute medical advice or a diagnosis. Reference ranges for free testosterone vary substantially between labs and assay methods (calculated vs. direct equilibrium dialysis vs. immunoassay) — more so than most hormone tests — so the ranges shown here are general guidance only. Always compare results primarily to the reference range printed on your own lab report, and interpret alongside symptoms and the full hormone panel with a qualified clinician.