An Evidence Map of Systematic Reviews to Inform Interventions in Prediabetes

Impaired glucose tolerance and impaired fasting glucose, referred to as prediabetes, are predisease states that may progress to type 2 diabetes mellitus. The value of intervening in these states, especially with respect to cardiovascular outcomes, is unclear. The purpose of this study was to develop a broad synopsis of the available literature through an evidence map of systematic reviews about interventions in adults with prediabetes. The Cochrane Library Issue 4, 2011, Ovid MEDLINE (1946-January 4, 2012) and grey literature were searched. Studies were selected according to defined eligibility criteria. Fourteen relevant systematic reviews, of mostly high quality, were retrieved. The majority of reviews evaluated pharmacotherapeutic interventions or diet/exercise/lifestyle. A few reviews assessed complementary alternative medicine, behavioural strategies, standard prevention education or gastric bypass surgery. Very few reviews reported data on clinical cardiovascular endpoints. Most reviews reported either shorter-term surrogate markers of cardiovascular outcomes or progression to type 2 diabetes mellitus. Based on an assessment of authors' overall conclusions, the value of pharmacotherapeutic interventions and diet/exercise/lifestyle ranged from beneficial to inconclusive, behavioural strategies were beneficial, and gastric bypass surgery was probably beneficial. The value of complementary alternative medicine was inconclusive. A considerable amount of evidence pertaining to interventions in prediabetes exists. Future research should synthesize the available systematic review evidence base in an overview of reviews. In addition, more primary research should be conducted to assess clinical cardiovascular endpoints. (C) 2012 Canadian Diabetes Association