Relationship between fasting blood glucose and HOMA-IR and body fat, waist-hip circumference (WHR), and body mass index (BMI) in patients not using oral antidiabetic medications applying to an obesity clinic

Purpose: Prediabetes represents the transitional stage preceding type 2 diabetes mellitus, and early detection during this period is critical for preventing future diabetes development. This study aimed to investigate the relationship between anthropometric measurements [body mass index (BMI), waist-to-hip ratio (WHR), body fat percentage (BFP)] and biochemical parameters [fasting plasma glucose (FPG), insulin, homeostasis model assessment of insulin resistance (HOMAIR)] in individuals attending an obesity outpatient clinic. Methods: This retrospective cross-sectional study included data from 444 individuals (43 men, 401 women) who attended the Obesity Outpatient Clinic of Tokat Gaziosmanpaşa University Faculty of Medicine between 2021 and 2023 and were not using oral antidiabetic therapy. Anthropometric (BMI, WHR, BFP) and biochemical parameters (FPG, insulin, HOMA-IR) were recorded. Statistical analyses were performed using descriptive statistics, group comparisons (t-test, Mann–Whitney U), chi-square tests, and receiver operating characteristic (ROC) curve analysis. Finding: The mean FPG was 95.7 ± 11.3 mg/dL, insulin 15.4 ± 10.1 μU/mL, and HOMA-IR 3.74 ± 2.85. The mean BMI was 35.8 ± 5.9 kg/m², WHR 0.93 ± 0.07, and BFP 46.3 ± 5.5%. When glucose levels were compared across anthropometric categories, no significant difference was observed by BMI (p=0.990), whereas glucose values were significantly higher in individuals with elevated WHR (p=0.005). No significant difference was detected between BFP groups. For HOMA-IR, although insulin resistance prevalence was higher in participants with BMI ≥30, this was not statistically significant (p=0.246). Conversely, participants with elevated WHR showed significantly higher rates of insulin resistance (p=0.011). BFP was not significantly associated with HOMA-IR (p=0.176). viii ROC analysis indicated that WHR was a strong predictor of insulin resistance in men (AUC=0.773; p=0.002), while its predictive ability was limited in women (AUC=0.586; p=0.003). Results: Our findings demonstrate that BMI alone is insufficient for predicting prediabetes, whereas WHR, particularly in men, serves as a stronger predictor of insulin resistance. In women, WHR showed limited specificity, suggesting that it should be evaluated alongside biochemical markers such as FPG and HOMA-IR. BFP was not a significant predictor of prediabetes in this cohort. These results highlight the clinical value of simple, low-cost anthropometric measurements, especially WHR, for the early detection of prediabetes. Keywords: Prediabetes, insulin resistance, HOMA-IR, obesity, waist-to-hip ratio, body fat percentage