MON-671 - BMI Thresholds of High Level Insulin Resistance in Adults With Normoglycemia According to Ethnicity

Introduction: The United States continues to experience a massive obesity epidemic, which is driving a progressive increase in the prevalence of metabolic disease, including prediabetes (PD) and type 2 diabetes (T2D). Public health efforts have focused on screening in middle adulthood to identify individuals with significant metabolic disease, specifically, PD. Public health efforts to slow the progression of PD to T2D have had limited impact. Long-term follow up of Diabetes Prevention Program (DPP) participants have demonstrated that >50% progressed to T2D at 15 years, suggesting that earlier identification of at-risk individuals with insulin resistance (IR) for intervention before the development of PD and T2D might be helpful.
Previously, we examined the distribution of IR using the insulin resistance risk score (IRRS) (Abassi, 2018; PMID: 30187017) in 16,333 adults with normoglycemia (NG) measured in 2020 and determined the IRRS distribution (tertile 1 [T1]: < 8%; T2: 8-20%; T3: >20%). We demonstrated that the risk of progression to PD or T2D was highest in T3, intermediate in T2, and lowest in T1 (Louie, 2026; PMID: 41485462).
IR is more prevalent in those with elevated BMI, however, the proportion of individuals with elevated levels of IR varies according to ethnicity. The objective of this study was to assess BMI thresholds that would be appropriate for BMI-based screening of IR in different ethnic groups.

Methods: The study included 21,053 adults with NG (fasting plasma glucose < 100 mg/dL and HbA1c < 5.7%) who participated in health screening in 2022. Top tertile IR (TTIR) (IRRS >20%) was examined according to BMI levels and self-reported ethnicities.

Results: Among the study population (N=21,053; mean [SD] age, 44 [12] years; 32% men), 13% (2,769) identified as African American, 15% (3,171) Asian, 14% (3,001) Hispanic, 45% (9,489) White, and 12% (2,623) other. The proportions of TTIR differed among ethnicities (P value < 0.001): 38% (95%CI, 36 to 40) in African Americans, 32% (95%CI, 30 to 33) in Asians, 45% (95%CI, 43 to 47) in Hispanics, 35% (95% CI, 34 to 36) in Whites, and 36% (95%CI, 34 to 38) in others. Among those with BMI ≥25 (N=14,088), 43% (95%CI 41 to 45) of 2,303 African Americans, 51% (95%CI, 48 to 54) of 1,411 Asians, 55% (95%CI, 53 to 57) of 2,209 Hispanics, and 47% (95%CI, 46 to 49) of 6,378 Whites had TTIR (P value < 0.001). Overall, TTIR was 48% (6,783).
TTIR thresholds differed according to ethnicity: among Asians with TTIR, about 10% had BMI ≤ 22, and about 50% with BMI ≤ 26. These BMI cut points were 24 and 30 for Hispanics, 24 and 31 for Whites, and 25 and 32 for African Americans.

Conclusions: Although universal screening to identify normoglycemic individuals with TTIR might be possible, screening according to ethnicity could be used to devise BMI-based thresholds to improve detection of TTIR.

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