Improvement of glycemic control in type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials

Aim: Different guidelines provide similar, but not identical, therapeutic targets for HbA1c in type 2 diabetes. These targets can also depend from the different pharmacological strategies adopted for intensifying glycemic control. Data synthesis: This meta-analysis includes randomized trials adopting any pharmacological regimen for intensifying glycemic control in T2DM (versus standard of care/placebo), with a trial duration >2 years and a between-group HbA1c difference>0.5%. The primary outcome was to assess the effects of the improvement of glycemic control on major cardiovascular events (MACE), ocular and renal complications, and severe hypoglycemia. Mantel-Haenszel odds ratios (MH-OR) with 95% Confidence Intervals were calculated for all the outcomes considered. We included 13 trials fulfilling the inclusion criteria. The improvement of glycemic control was associated with a lower risk of MACE (MH-OR:0.89 [95%CI 0.85-0.94]) and renal adverse events (MH-OR 0.73 [0.65-0.82]), but not all-cause mortality (MH-OR 0.95 [0.88-1.01]) and ocular adverse complications (MH-OR 0.94 [0.72-1.22]). For glucose-lowering drugs inducing hypoglycemia, a protective effect on the risk of microvascular complications, but not of MACE and all cause mortality, was observed only for HbA1c < 48 mmol/mol, but with higher risk of severe hypoglycaemia (MH-OR 2.72 [1.79-4.13]). Drugs not inducing hypoglycaemia were associated with a reduction of MACE, renal adverse events, and all-cause mortality, for HbA1c< 7% (no data for lower targets). Conclusions: The present meta-analysis show that the improvement of glycemic control with drugs not inducing hypoglycemia is associated with a reduction in the risk of long-term chronic vascular and renal complications, and all-cause mortality. (c) 2021 The Italian Diabetes Society, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.