Association between insulin-induced weight change and CVD mortality: Evidence from a historic cohort study of 18,814 patients in UK primary care.

BACKGROUND: This study explores the association of insulin-induced weight (wt) gain on cardiovascular outcomes and mortality among patients with type 2 diabetes (T2D) following insulin initiation using real-world data. METHODS: A historical cohort study was performed in 18,814 adults with insulin-treated T2D derived from the UK The Health Improvement Network database. Based on the average weight change of 5 kg, 1 year postinsulin initiation, patients were grouped into 5 categories (>5 kg wt loss; 1.0-5.0 kg wt loss; no wt change; 1.0-5.0 kg wt gain; >5.0 kg wt gain) and followed-up for 5 years. Cox proportional hazard models and Kaplan-Meier estimators were fitted to estimate the hazards of a 3-point composite of nonfatal myocardial infarction, stroke, and all-cause mortality between categories. RESULTS: The median age was 62.8 (IQR: 52.3-71.8) years, HbA1c : 8.6% (IQR: 7.4-9.8) and mean BMI: 31.8 (6.5) kg/m2 . The 5 year probability of survival differed significantly within the wt-change categories (log-rank test P value = .0005). Only 1963 composite events occurred. Compared with the weight-neutral group, the risk of composite events was 31% greater in the >5 kg wt-loss group (aHR: 1.31; 95% CI: 1.02, 1.68), the same in the 1.0 to 5.0 kg wt-gain category, but nonsignificantly increased in the 1.0 to 5.0 kg wt loss (15%) and >5.0 kg wt gain (13%) categories, respectively. In the obese subgroup, this risk was 50% (aHR: 1.50, 95% CI: 1.08-2.08) more in the >5 kg weight-loss group compared with the weight-neutral group. CONCLUSION: Insulin-induced weight gain did not translate to adverse cardiovascular outcomes and mortality in patients with T2D. These data provide reassurance on the cardiovascular safety of insulin patients with T2D.