Obesity and increased risk of type 2 diabetes mellitus : the aetiological role of depression

Obesity, defined using body mass index (BMI) values ≥30 kg/m2 (calculated as weight in kilograms divided by height in meters squared), is a serious medical condition almost entirely due to excess dietary intake. It is estimated that 205 million men and 297 million women older than 20 years worldwide were obese in 2008 [1]. The age-standardised prevalence of obesity was approximately 10% in men and 14% in women "” nearly double the 1980 prevalence estimates. One of the most important consequences of high and rising trends in global obesity prevalence has been the increasing number of people developing type 2 diabetes mellitus (T2DM) [2]. Indeed, the International Diabetes Federation (IDF) reports that some 366 million people worldwide, or 8% of adults, are now estimated to have diabetes, and that lifestyle therapy should be used to achieve a healthy BMI in the prevention and management of T2DM [3]. The rising health and economic burden of T2DM disproportionately affect older, obese, and physical inactive people [4], as well as those with depression [5]. Reliable information about the aetiological role of depression in obesity and consequential T2DM could lead to more effective management and prevention planning, resulting in significant health and economic benefits.