GDM Screening: GCT and OGTT Diagnostic Thresholds

Interpret 50g GCT and 100g 3-hour OGTT (Carpenter-Coustan or NDDG criteria) or 75g 2-hour OGTT (IADPSG/WHO criteria) for gestational diabetes mellitus (GDM) diagnosis. Two abnormal values on OGTT or any one value on IADPSG criteria.

Weight
Height
Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.
Advertisement

How to Use

Enter the values for the scenario you are assessing. Interpret 50g GCT and 100g 3-hour OGTT (Carpenter-Coustan or NDDG criteria) or 75g 2-hour OGTT (IADPSG/WHO criteria) for gestational diabetes mellitus (GDM) diagnosis. Two abnormal values on OGTT or any one value on IADPSG criteria. Use the gdm gct ogtt result to inform your calculation.

Frequently Asked Questions