Endocrinology and Diabetes Calculators

ADA 2026 guidelines recommend an HbA1c target <7% (53 mmol/mol) for most non-pregnant adults with type 2 diabetes. A less stringent target of <8% is appropriate for older adults, those with limited life expectancy, advanced complications, or significant hypoglycemia risk. More stringent targets (<6.5%) may be individualized in younger patients with recent diagnosis, no cardiovascular disease, and minimal hypoglycemia risk when achievable without excessive burden.

The insulin correction factor (sensitivity factor) estimates how much 1 unit of rapid-acting insulin lowers blood glucose. Two common rules: the '1700 rule' (1700 ÷ total daily dose) for regular insulin, or the '1800 rule' (1800 ÷ TDD) for rapid-acting analogs. For example, a TDD of 50 units gives a correction factor of ~36 mg/dL per unit. Always confirm with the patient's actual glucose response and adjust for time of day, physical activity, and illness.

TSH is the most sensitive test for thyroid dysfunction. Normal TSH range is typically 0.4–4.0 mIU/L, though reference ranges vary by lab and age. TSH <0.4 with elevated T4/T3 = hyperthyroidism. TSH >4.0 with low T4 = overt hypothyroidism; TSH >4.0 with normal T4 = subclinical hypothyroidism. In the elderly, TSH up to 6–7 mIU/L may be acceptable. In pregnancy, trimester-specific ranges apply (TSH <2.5 mIU/L in first trimester per ATA guidelines).

HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) = fasting insulin (µIU/mL) × fasting glucose (mmol/L) ÷ 22.5. Values >2.0–2.5 suggest insulin resistance; >3.0 is commonly used as a clinical cut-off. HOMA-IR is a research tool not validated for individual clinical decision-making — it is most useful for population studies and assessing response to interventions. Fasting state (8–12 hours) is essential for accurate measurement.

Glucocorticoid potency is expressed relative to hydrocortisone (= 1). Approximate equivalent anti-inflammatory doses: hydrocortisone 20 mg = prednisone 5 mg = methylprednisolone 4 mg = dexamethasone 0.75 mg. These are anti-inflammatory equivalences — mineralocorticoid activity and duration differ significantly. Dexamethasone has negligible mineralocorticoid activity. When converting, always consider the clinical indication, route of administration, and half-life differences.

Initial levothyroxine dosing for overt hypothyroidism: 1.6 mcg/kg/day of ideal body weight in young, healthy adults. Start lower (25–50 mcg/day) in elderly patients, those with cardiac disease, or longstanding hypothyroidism. Adjust by 12.5–25 mcg every 6–8 weeks, guided by TSH levels. For central hypothyroidism, target free T4 in the upper half of the normal range (not TSH). In pregnancy, dose requirements increase 20–30% immediately upon diagnosis.