OBJECTIVE: The key objective of the present investigation was to compare associations between sagittal abdominal diameter (SAD), waist circumference, and BMI to the oral glucose tolerance test (OGTT), along with fasting glucose, HbA1c, and HOMA-IR, in a nationally representative sample of U.S. adults. The study also analyzed the effect of multiple covariates on the anthropometric and glucose metabolism associations. METHODS: A cross-sectional design, including 3,582 subjects, was used. SAD was assessed using an abdominal caliper. All other data were collected following strict NHANES protocol. The OGTT was the primary variable used to index glucose metabolism. Fasting glucose, HbA1c, and HOMA-IR were also evaluated. RESULTS: Mean ± SE values were as follows: SAD: 22.3 ± 0.1 cm; waist circumference: 98.0 ± 0.4 cm; BMI: 28.6 ± 0.2 kg/m2; OGTT: 113.9 ± 1.0 mg/dL; fasting glucose: 99.6 ± 0.3 mg/dL; HbA1c: 5.4 ± 0.01%; HOMA-IR: 3.2 ± 0.1. SAD consistently emerged as the best predictor of all the indices of glucose metabolism, before and after adjusting for the covariates, and with the sample stratified by gender, race, or age. SAD was not a better predictor of OGTT among normal weight adults and non-Hispanic black adults. CONCLUSION: Obesity, especially abdominal obesity, is strongly related to glucose metabolism and type 2 diabetes. In the present study, SAD was the best anthropometric predictor of glucose metabolism, notwithstanding the high correlations among SAD, waist circumference, and BMI. Due to the ease of taking a SAD measurement, we recommend that healthcare providers consider the use of this simple and inexpensive method to more precisely predict diabetes risk, especially among overweight and obese adults.



College and Department

Life Sciences; Exercise Sciences



Date Submitted


Document Type





obesity, abdominal obesity, visceral fat, anthropometry, type 2 diabetes, oral glucose tolerance test