Relationship between HbA1c and all-cause mortality in older patients with insulin-treated type 2 diabetes: results of a large UK Cohort Study.

Abstract

our aim was to study the relationship between HbA1c and cardiovascular morbidity and all-cause mortality among older insulin-treated patients with type 2 diabetes (T2D) after adjustment for multiple confounders. data for 4589 adults with T2D (>65 years) on insulin treatment were sourced from 532 UK General Practices via the Health Improvement Network (THIN) database. Cox proportional hazard models and Kaplan-Meier estimators were fitted to derive the hazards of all-cause mortality by HbA1c categories (<6.5, 6.5-7.4, 7.5-8.4, 8.5-9.4, 9.5-10.4, 10.5-11.4%; and 11.5% and above) after 5 years of follow-up following insulin initiation. we observed a U-shaped relationship between all-cause mortality and HbA1c, with the lowest risk seen in the HbA1c range of 6.5-7.4% and marked increased in risk with HbA1c > 11%. The highest mortality risks of 31 and 40% were significantly associated with the lowest (<6.5%) and highest (11.5% and above) HbA1c categories: aHR: 1.31; (95%CI: 1.10-1.56; P = 0.002) and aHR: 1.40; (95%CI: 1.01-1.96; P = 0.039), respectively. both low and high HbA1c were associated with increased all-cause mortality, among older patients with insulin-treated T2D. This cohort study supports the need for individualisation of care and suggests better outcomes with HbA1c levels around 6.5-7.4% and markedly excess risk with HbA1c > 11.