Association of HOMA-IR Versus TyG Index with Diabetes in Individuals Without Underweight or Obesity

Background: There are higher numbers of Asian individuals with metabolically obese, normal weight (MONW) who are susceptible to diabetes than other ethnic groups. The homeostatic model assessment for insulin resistance (HOMA-IR) has been used for years to evaluate IR; however, the triglyceride-glucose (TyG) index has been highlighted as a reliable and cost-effective insulin resistance indicator. Thus, this study explored the association of the HOMA-IR versus the TyG index with diabetes in individuals without underweight or obesity. Methods: This cross-sectional study included 10,471 Korean individuals whose body mass index was ≥18.5 and <25.0 kg/m². Depending on metabolic syndrome criteria, subjects with no conditions, one or two conditions, and three or more conditions were assigned to the metabolically healthy and normal weight (MHNW), pre-MONW, and MONW groups, respectively. Diabetes was diagnosed based on HbA1C and medication information. Results: The HOMA-IR and TyG index discriminated between each group, showing an increasing trend from the MHNW group to the MONW group. However, this trend was more robust for the TyG index. The cut-off values in the TyG index and HOMA-IR were >8.9 and >1.6 in males and >8.7 and >1.6 in females, respectively. The TyG index's area under the curve was higher than that of the HOMA-IR in both sexes. MONWs distinguished by the cut-off values of the TyG index and HOMA-IR were 2.370 and 1.726 for males and 2.249 and 1.710 for females times more likely to develop diabetes. Conclusions: The TyG index showed a stronger association with diabetes in Korean individuals without underweight or obesity than the HOMA-IR.