Effects of insulin on cardiovascular events and all-cause mortality in patients with type 2 diabetes: A meta-analysis of randomized controlled trials.

Aim: In 2019, the Italian Society of Diabetology and the Italian Association of Clinical Diabetologists nominated an expert panel to develop guidelines for drug treatment of type 2 diabetes. This expert panel, after identifying the effects of glucose-lowering agents on major adverse cardiovascular events (MACEs), all-cause mortality, and hospitalization for heart failure (HHF) as critical outcomes, decided to perform a systematic review and meta-analysis on the effect of insulin with this respect.
Data Synthesis: A MEDLINE database search was performed to identify all RCTs, up to June 1st, 2021, with duration≥52 weeks, in which insulin was compared with either placebo or active comparators. The principal endpoints were MACE and HHF (restricted for RCT reporting MACEs within their outcomes), all-cause mortality (irrespective of the inclusion of MACEs among the pre-specified outcomes). Mantel-Haenszel odds ratio (MH-OR) with 95% Confidence Interval (95% CI) was calculated for all the endpoints considered. Six RCTs (enrolling 8091 patients and 10,139 in the insulin and control group, respectively) were included in the analysis for MACEs and HF, and 18 in that for all-cause mortality (9760 and 11,694 patients in the insulin and control group, respectively). Treatment with insulin neither significantly increased nor reduced the risk of MACE, all-cause mortality, and HHF in comparison with placebo/active comparators (MH-OR: 1.09, 95% CI 0.97-1.23; 0.99, 95% CI 0.91, 1.08; and 0.90, 95% CI 0.78, 1.04, respectively).
Conclusions: This meta-analysis showed no significant effects of insulin on incident MACE, all-cause mortality, and HHF.
Competing Interests: Declaration of competing interest MM has received speaking fees from Astra Zeneca, Bristol Myers Squibb, Boehringer-Ingelheim, Eli-Lilly, Merck, Novo Nordisk, Sanofi, and Novartis and research grants from Bristol Myers Squibb; EM has received consultancy fees from Merck and Novartis speaking fees from Astra Zeneca, Bristol Myers Squibb, Boehringer-Ingelheim, Eli-Lilly, Merck, Novo Nordisk, Sanofi, and Novartis and research grants from Merck, Novartis, and Takeda. AG has received speaking fees and/or advisory board invitations from Abbott, Astra Zeneca, Boehringer-Ingelheim, Eli Lilly, MSD, Mundipharma, Novo-Nordisk, Sanofi. BN was an employee of NovoNordisk. The other authors did not report any relevant conflicts of interest. All the authors approved the final version of this manuscript. Dr. Edoardo Mannucci is the person who takes full responsibility for the work as a whole, including the study design, access to data, and the decision to submit and publish the manuscript.
(Copyright © 2022 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.)