Lean Type 2 Diabetes Mellitus

Type 2 diabetes is increasing in epidemic proportions across the globe. Obesity is generally considered to be the major contributor to the epidemic of diabetes mellitus. In NHANES 1999–2002 study from USA around 55% of diabetics were obese (Eberhardt & Ogden, 2004) The focus in the Western world remains on the more prevalent overweight or obese patient, but a significant proportion of diabetes cannot be attributable to obesity using current criteria. A large proportion of patients with type 2 diabetes are ‘lean or underweight.’ In the Diabetes and Informatics (DAI) study in Italy involving over 13,000 patients with type 2 diabetes, approximately 25% had a body mass index (BMI) ≤ 25 kg/m2 and rates of obesity were 23% in men and 37% in women (Mannucci et al. 2004). Likewise, in a study involving over 2700 people with type 2 diabetes attending a secondary care diabetes clinic in the UK, 14% had a BMI ≤ 25 kg/m2 and 52% were Obese (Daousi & Casson, 2006). There is some controversy, however, as to what exactly defines a lean patient with type 2 diabetes. There is uncertainty regarding the choice of the most appropriate parameters and their thresholds for defining overweight and obesity, the influence of different patient characteristics, such as ethnicity and age (National Heart, Lung, and Blood Institute Expert Panel on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults, 1998). In South Asians, people who are not overweight by traditional weight criteria (i.e. BMI) may have an increased percentage of body fat, particularly the more metabolically active intra-abdominal fat (Deurenberg-Yap et al.,