Reflecting on type 2 diabetes prevention: more questions than answers

Given the enormous public health and economic burden posed by the global epidemic of type 2 diabetes mellitus (T2DM), intervention in the prediabetes stage of disease to prevent progression to T2DM and its vascular complications seems the most sensible approach. Precisely how best to intervene remains the subject of much debate. Prudent lifestyle changes have been shown to significantly reduce the risk of progression in individuals with impaired fasting glucose (IFG) and impaired glucose tolerance (IGT). Although lifestyle modifications are notoriously difficult to maintain, there is evidence that intensive intervention results in continued preventive benefit after the stopping of structured counselling. A number of drug therapies, including metformin, acarbose, orlistat and rosiglitazone, have also been proven effective in preventing progression from IFG/IGT, but unresolved issues still remain. Specifically, whether large numbers of individuals with glucose dysregulation who may never progress to T2DM should be exposed to the risk of pharmacological adverse effects is a topic of discussion and debate. Furthermore, there are limited data on the effectiveness of implementing interventions during the prediabetic state to prevent cardiovascular complications that may be hyperglycaemia related. A recent American Diabetes Association (ADA) consensus statement on IFG/IGT recommends lifestyle modification for individuals with IFG or IGT. Of note, the ADA consensus statement introduces the option of adding metformin treatment to lifestyle changes in those individuals who have combined IFG/IGT plus an additional risk factor for progression and who also have some features that increase the likelihood of benefiting from metformin treatment. The dipeptidyl peptidase-4 inhibitors are a new class of oral antidiabetic agents that, in addition to being effective in improving glycaemic control, may exert beneficial effects in preserving beta-cell function. These characteristics, combined with a low risk of hypoglycaemia, weight neutrality and what appears - so far - to be a relatively benign tolerability profile, make these agents intriguing candidates for preventive treatment.