Comparison of Two Estimated Glucose Disposal Rate Methods for Detecting Insulin Resistance in Adults with Type 1 Diabetes Mellitus

Background: The presence of insulin resistance (IR) in patients with type 1 diabetes mellitus (T1DM) is a significant indicator of all chronic diabetic complications, independent of other risk factors. The estimated glucose disposal rate (eGDR) is a practical method that can be easily used in daily practice to determine IR. This study aimed to determine the cutoff values for two eGDR methods and compare their diagnostic value for determining IR in adult T1DM patients with metabolic syndrome (MetS). Methods: This cross-sectional study was performed on 184 adults admitted to the endocrinology outpatient clinic diagnosed with T1DM. Demographic characteristics, anthropometric measurements, and the presence of hypertension (HT) were recorded. The eGDR of all patients was calculated using two formulas based on HbA1c level, presence of HT, waist-to-hip ratio (WHR), or waist circumference (WC). Diagnostic cutoff values for both eGDRs were defined using receiver operating characteristic (ROC) analysis. Patients were divided into two groups according to the cutoff values. The accuracy of the diagnostic cutoffs for eGDRwhr and eGDRwc was compared using a Bland-Altman plot. Results: The cutoff value for eGDRwhr was 7.37 mg/(kg·min) with 83.3% specificity and 86.7% sensitivity [area under the curve (AUC) = 0.901; P < 0.001; 95% confidence interval (CI), 0.824-0.977] and for eGDRwc 7.50 mg/(kg·min) with 79.8% specificity and 83.3% sensitivity (AUC = 0.895; P < 0.001; 95% CI, 0.817-0.972) for the presence of MetS. Further ROC analysis showed that the difference between the two AUCs (0.901 and 0.895) was not significant (P = 0.923). Conclusion: Assessment of eGDR would lead to early prevention of diabetic complications. eGDR is measured using either WHR or WC. This study is the first to compare WHR and WC in calculating eGDR in adults. WHR and WC are not superior to each other for calculating eGDR in determining IR in T1DM.