Introduction: Type 2 diabetes mellitus is a metabolic disease characterized by insulin resistance and defective insulin secretion. Quantification of insulin resistance is essential as it may guide treatment options. The aim of the study was to compare HOMA-IR (both insulin and C-peptide based) and QUICKI in type 2 diabetes mellitus patients.
Methodology: The cross-sectional study included a hundred and fourteen type 2 DM patients diagnosed as per the American Diabetic Association 2017 guidelines. Fasting blood glucose, insulin and C-peptide were assayed. Insulin resistance and beta cell functioning were calculated by HOMA for insulin and C-peptide using suitable formulas. Linear regression analysis was done to correlate insulin and C-peptide based HOMA.ROC curves were constructed to compare different insulin sensitivity indices.
Results: There was a significant correlation (p=0.007) between insulin and C-peptide based HOMA-IR (r=0.3654. r2=0.1335). Insulin and C-peptide based HOMA1% B also had a significant correlation, p=0.0066 (r=0.2975. r2=0.08850). Insulin and C-peptide based HOMA-B cell also had a significant correlation, p=0.0019 (r=0.3223. r2=0.1039). A linear negative correlation was observed between QUICKI and HOMA-IR (p=0.0001) and HOMA-C (p=0.0004) respectively. ROC curve showed that C-peptide based HOMA model had the highest area under the curve, 0.836 with better sensitivity and specificity compared to other insulin resistance/sensitivity models.
Conclusion: Insulin and C-peptide based HOMA-IR are positively correlated. C-peptide based HOMA is a more sensitive and specific marker of insulin resistance compared to insulin based HOMA-IR and QUICKI.