Phenotypes in Focus: Novel Clusters of Type 2 Diabetes in North India

Abstract

Background and Objective: Type 2 diabetes mellitus is a heterogeneous condition with wide variation in clinical features, metabolic defects, and risk of complications. A refined classification based on metabolic abnormalities may help in tailoring treatment and predicting outcomes. Study Design and Methodology: In this cross-sectional study, hundred patients attending the Medicine and Endocrinology outpatient departments of a tertiary hospital were grouped into four phenotypes using insulin deficiency (C‑peptide less than 0.6 ng/mL), insulin resistance (HOMA‑IR greater than 2), and obesity (body mass index above 25 kg/m²). Clinical and biochemical parameters, glycemic control, insulin requirement, and the prevalence of vascular complications were compared. Results: Among 100 participants, Insulin Resistant Obese Diabetes was most common (57%), followed by Mild Age‑Related Diabetes (27%), Combined Insulin Resistant and Deficient Diabetes (11%), and Severe Insulin Deficient Diabetes (5%). Severe Insulin Deficient Diabetes showed the youngest age at diagnosis, highest body mass index, and strongest link with microvascular complications. Insulin Resistant Obese Diabetes had the poorest glycemic control. Mild Age‑Related Diabetes was associated with the oldest age at diagnosis and lowest glycated hemoglobin levels. Combined Insulin Resistant and Deficient Diabetes displayed overlapping features. Conclusions: These findings highlight substantial heterogeneity in the Indian population and suggest the need for further studies to refine subclassification and guide precision medicine.