A pathogenic relationship exists between type 2 diabetes and obesity. Over the last decade, the escalation in diabetes cases has paralleled the rapid increase in obesity rates, constituting a global health crisis. Environmental risk factors attributed to the global increase in obesity include the consumption of high-calorie, high-fat foods and inadequate physical activity. Obese individuals may also have a genetic predisposition for obesity. Both diabetes and obesity confer an elevated risk of developing a range of complications and comorbidities, including cardiovascular disease, hypertension and stroke, which can complicate disease management. This review examines the aetiology of the linkages between diabetes and obesity and the range of available therapies. Recent clinical evidence substantiating the efficacy and safety of incretin-based antidiabetic therapies is analysed, in addition to data on antiobesity therapeutic strategies, such as antiobesity agents, behaviour modification and bariatric surgery. Glucose control is often accompanied by weight-neutral or modest weight reduction effects with DPP-4 inhibitor treatment (sitagliptin, vildagliptin, saxagliptin) and weight loss with GLP-1 receptor agonist therapy (exenatide, liraglutide). Studies of antiobesity agents including orlistat, sibutramine and rimonabant have shown attrition rates of 30-40%, and the long-term effects of these agents remain unknown. Bariatric surgical procedures commonly performed are laparoscopic adjustable banding of the stomach and the Roux-en-Y gastric bypass, and have produced type 2 diabetes remission rates of up to 73%. Therapeutic strategies that integrate glycaemic control and weight loss will assume greater importance as the prevalence of diabetes and obesity increase. Keywords: DPP-4, exenatide, GLP-1 analogue, human, incretin, liraglutide, once-daily, type 2 diabetes mellitus
Date submitted 2 June 2009; date of first decision 2 November 2009; date of final acceptance 4 November 2009
IntroductionThe term 'diabesity', coined by Sims and colleagues [1] in the 1970s, describes the strong link between type 2 diabetes and obesity [1,2]. As evidence of this pathogenic interrelationship continues to accumulate, so does the appearance of the term in the clinical literature. A large body of clinical evidence attests to the relationship between being overweight or obese and being at an elevated risk for development of type 2 diabetes [3][4][5][6][7]. The risk escalates with the degree of excess weight, increasing threefold with a body mass index (BMI) of 25.0-29.9 kg/m 2 and 20-fold with a BMI over 30 kg/m 2 [4]. In particular, abdominal fat accumulation exacerbates insulin resistance and confers a strong, independent risk of developing diabetes [8]. Global diabetes prevalence is estimated at 171 million and is projected to more than double, to 366 million, by 2030 [9]. Countries with the highest numbers of diabetes cases include India, China, USA, Indonesia and Japan [9][10][11]. The greatest relative increases in diabetes incide...