Diabetes Research and Clinical Practice 38 (1997) 101–108 Clinical profile of lean NIDDM in South India V. Mohan a, *, R. Vijayaprabha a , M. Rema a , G. Premalatha a , S. Poongothai a , R. Deepa a , E. Bhatia b , I.R. Mackay c , P. Zimmet c a M adras Diabetes R esearch Foundation and M .V . Diabetes Specialities Centre, 35 Conron Smith Road, M adras 600086, India b Sanjay Gandhi Postgraduate Institute of M edican Sciences, Rae Barelli Road, Lucknow, India c International Diabetes Institute, Caulfield, Victoria 3162, A ustralia Received 1 June 1996; received in revised form 23 June 1997; accepted 23 July 1997 Abstract The majority ( 80%) of patients with non insulin dependent diabetes mellitus (NIDDM) present in Europe and America are obese. In developing countries like India, most NIDDM ( 60%) are non-obese and many are actually lean with a body mass index (BMI) of 18.5 and are referred to as ‘lean NIDDM’. This paper compares the clinical profile of a cohort of 347 lean NIDDM, with a group of 6274 NIDDM of ideal body weight (IBW) and 3252 obese NIDDM attending a diabetes centre at Madras in South India. The lean NIDDM who constituted 3.5% of all NIDDM patients seen at our centre, had more severe diabetes and an increased prevalence of retinopathy (both background and proliferative), nephropathy and neuropathy. Although a larger percentage of the lean NIDDM patients were treated with insulin, 47% of the males and 53% of the females were still on oral hypoglycaemic agents even after a mean duration of diabetes of 9.2 8.1 years. Studies of GAD antibodies, islet cell antibodies (ICA) and fasting and stimulated C-peptide estimations done in a small subgroup of the lean NIDDM showed that they were distinct from IDDM patients. More studies are needed on metabolic, hormonal and immunological profile of lean NIDDM seen in developing countries like India. © 1997 Elsevier Science Ireland Ltd. Keywords: Lean NIDDM; Non-obese; NIDDM; Complications; Retinopathy; Nephropathy; Neuropathy; C-peptide; Gad-antibodies; Islet cell antibodies; South India 1. Introduction The WHO study group report classifies patients with non insulin dependent diabetes mellitus (NIDDM) into ‘obese’ and ‘non-obese’ groups, using a body mass index (BMI) criteria of 25 *Corresponding author. Tel.: +91 44 8263038; fax: +91 44 8258935. 0168-8227/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved. PII S0168-8227(97)00088-0