Metabolic control and risk of hypoglycaemia during the first year of intensive insulin treatment in type 2 diabetes: systematic review and meta-analysis

Aim: Aim of this study was to analyse clinical correlates of HbA1c, and of overall, nocturnal, and severe hypoglycaemia, through direct-weighted regressions, as well as the effect of different insulin regimens and insulin analogues, through meta-analysis. Methods: Appropriate methodology (PRISMA statement) was used. Sixty-seven randomized studies, published as full papers were analysed to identify predictors of both HbA1c and hypoglycaemia; studies were included in a meta-analysis to study the effect of different insulin regimens or insulin analogues on HbA1c and hypoglycaemia during the first year of insulin treatment in type 2 diabetes patients. Results: Final HbA1c, change of HbA1c, hypoglycaemia, nocturnal hypoglycaemia and severe hypoglycaemia were associated with intensity of treatment. Final HbA1c was higher with basal than with twice-a-day or prandial, and with twice-a-day than with prandial regimen, with opposite figures for hypoglycaemia. Within basal regimens, detemir and glargine were similar to NPH insulin on HbA1c, with less hypoglycaemia and nocturnal hypoglycaemia; within prandial regimens, new analogues were more effective than regular insulin on HbA1c, and induced less hypoglycaemia. The effect of glargine on HbA1c and on hypoglycaemia vanished with increasing number of insulin injections. Conclusion: Metabolic control and hypoglycaemia are associated with intensity of treatment. Basal regimens have a reduced effect on metabolic control, but are associated with lower frequency of hypoglycaemia. Newer analogues, short-and long-acting, yield better control and less hypoglycaemia than older analogues.