Increase of body weight during the first year of intensive insulin treatment in type 2 diabetes: systematic review and meta-analysis

Aim: This systematic review and meta-analysis was to evaluate the body weight increase and its clinical correlates, through direct weighted regressions, as well as the effect of different insulin regimens and insulin analogues, through meta-analysis. Methods: Appropriate methodology according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was adhered to. Forty-six randomized studies, published as full papers, reporting the effect of insulin treatment on change in body weight were identified, and used to identify predictors of weight change; studies were included in a meta-analysis to study the effect of different insulin regimens or insulin analogues on weight change. Results: Intensity of treatment [aim of study (fasting blood glucose, mg/dl), dose of insulin, final HbA1c, change of HbA1c and frequency of hypoglycaemia] was significantly associated with body weight increase, with small differences between basal versus twice-a-day and prandial regimen. At meta-analysis, body weight increase was lower with basal regimen than with twice-a-day regimen and than with a prandial regimen. Within all regimens, body weight increase was lower with detemir than with NPH, with no difference between glargine and NPH; only two studies directly compared detemir and glargine, indicating lower weight gain with the former insulin. Within twice-a-day regimens and within prandial regimens, comparison was between newer analogues and older drugs, with no significant difference in body weight increase. Conclusion: Body weight increase during the first year of insulin treatment is associated with the intensity of treatment; body weight increase also depends on the insulin regimen applied.