Abstract
Disclosure: J.Z. Louie: Quest Diagnostics. D. Shiffman: Quest Diagnostics. J.B. Meigs: Quest Diagnostics. M.J. McPhaul: Quest Diagnostics. The number of individuals with obesity and type 2 diabetes (T2D) has progressively increased in the United States and in developed countries worldwide. Efforts to prevent T2D have centered on individuals with prediabetes through lifestyle changes or prescription medications. Preventing development of T2D earlier, before dysglycemia is manifested, could be an alternative strategy to interrupt disease progression. Therefore, standardized tools to identify those with normoglycemia and insulin resistance, who are at risk for prediabetes and T2D may be useful. We investigated whether BMI elevation would be a useful marker to identify individual with normoglycemia who would benefit from insulin resistance assessment. The study included 16,333 working-age adults with normoglycemia (fasting plasma glucose <100 mg/dL and HbA1c <5.7%) who participated in an annual wellness program. Insulin resistance was assessed with an insulin resistance risk score (IRRS) based on fasting intact insulin and C-peptide. IR was defined as IRRS in the top tertile (IRRS > 20%). The relationships between log-transformed IRRS levels and ethnicity or BMI were assessed in linear models.The 16,333 study participants had mean (SD) age of 44 (12) years. Of these, 66% were women. The population were ethnically diverse: 2015 (12.3%) self-identified as African American, 2321 (14.2%) as Asian, 2269 (13.9%) as Hispanic, 6898 (42.2%) as White, and 2830 (17.3%) as Other. Median (IQR) IRRS levels differed between the populations: 14% (7 - 33) in African American; 10% (5 - 22) in Asian; 16% (8 - 39) in Hispanic; 11% (6 - 27) in White; 12% (6 - 28) in Other (P <0.001 for difference between each ethnic group and Whites). The association between IRRS and BMI was significant (P <0.001). The IRRS levels rose as BMI levels increased in each ethnicity. The rate of IRRS levels per BMI level was higher in Asians (P interaction [P intxn] <0.001), lower in African Americans (P intxn <0.001), and similar in Hispanics (P intxn =0.11) compared with Whites. The participants with obesity or severe obesity (BMI ≥30) were 233 (10.0%) in Asians, 968 (48.0%) in African Americans, 756 (33.3) in Hispanics, 2104 (30.5%) in Whites, and 858 (30.3%) in others. In those with BMI ≥30, greater than 50% had IRRS >20%: 67.4% in Asians, 51.8% in African Americans, 67.1% in Hispanics, 61.3 % in Whites, and 57.1% in others. Our study found that higher IRRS levels in normoglycemic adults was significantly associated with higher BMI levels, and the effect of BMI levels on IRRS levels differed between ethnicities. BMI may be used to identify normoglycemic adults for insulin resistance screening to prevent or delay type 2 diabetes or CVD development and to assess insulin resistance differently in each ethnicity. Presentation: Monday, July 14, 2025