BMI-C as a Predictor of Type 2 Diabetes: Validation in Two Independent NHANES Cohorts (2015-16 and 2017-18)

Abstract Objective: To validate BMI-C (Body Morphometric Index – Corrected) as a predictor of Type 2 Diabetes (T2D) in two independent cohorts of the North American population, and to compare its performance with that of traditional body mass index (BMI).

Methods

Cross-sectional study using NHANES 2015-16 (N=6,321) and 2017-18 (N=6,015) data. BMI-C was calculated using the proprietary algorithm available at bmi-c.com, using waist circumference (cm), height (cm), weight (kg), age (years), and sex as inputs. T2D was defined by self-reported diagnosis, use of insulin or oral hypoglycemic agents, HbA1c ≥ 6.5%, or fasting glucose ≥ 126 mg/dL. ROC curves, age- and sex-adjusted logistic regression, and relative risk by category were calculated. BMI was calculated as weight/height² for comparison. The 95% CI of AUCs was estimated by bootstrap (2,000 resamples).

Results

T2D prevalence was 15.0% (2015-16) and 13.3% (2017-18). BMI-C showed an AUC of 0.738 (95% CI: 0.723–0.755) and 0.719 (95% CI: 0.702–0.736), respectively. BMI showed an AUC of 0.687 (95% CI: 0.670–0.704) and 0.662 (95% CI: 0.642–0.681). The AUC difference was +0.051 and +0.057. The optimal BMI-C cut-off was 1.32 and 1.29; the optimal BMI cut-off was 26.7 and 27.8 kg/m². The age- and sex-adjusted odds ratio for BMI-C was 12.48 (95% CI: 7.85–19.86) and 18.58 (95% CI: 11.47–30.09). The dose-response relationship was consistent across cohorts: T2D risk ranged from 2.1% (BMI-C 0.8–0.9) to 42.9% (BMI-C 1.8–1.9) in 2015-16, and from 0.0% to 33.0% in 2017-18.