Etiopathological differentiation of diabetes mellitus in lean, young adults.

Objective: Classification of diabetes mellitus (DM) into type 1 or type 2 is difficult in lean, young individuals. We studied the β-cell function, insulin resistance (IR) and autoimmunity in young patients with recent onset DM.

Methods: In this cross-sectional study, we included patients (age below 35 years) with recent onset DM (<6 months) and normal body weight for evaluation. The detailed clinical examination was done to identify markers of IR. Autoimmune DM was diagnosed using glutamic acid decarboxylase 65 (GAD), insulin autoantibody (IAA) and islet cell antibody (ICA). Homeostasis model assessment (HOMA) models of HOMA-B and HOMA- IR were used for estimation of β-cell function and IR respectively. The patients were divided into four groups based on, the autoimmunity (A) and ketosis (K) as group 1 (A+K), group 2 (A-K+), group 3 (A+K-) and group 4 (A-K-). Appropriate statistical tests +)were used to analyze the results.

Results: The study population (n=75, all males) had a mean age of 28.9±4.3years, body mass index 20.6±1.9kg/m, fasting plasma glucose 177.1±31.4mg/dl and HbA1c of 9.9±2.1% at presentation. The number of patients in groups 1 to 4 are 8, 5, 10 and 52 respectively (p<0.0001). HOMA-IR was higher in groups 2 and 4 (4.1±1.3, 3.6±1.1 respectively), whereas HOMA-B was higher in group 4 (3.6±1.5) alone (p=0.0005).

Conclusion: Type 2 DM is the most common etiology even in young, lean adults in India. Further studies with large numbers are required to confirm our findings.