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

Background our aim was to study the relationship between HbA_1c and cardiovascular morbidity and all-cause mortality among older insulin-treated patients with type 2 diabetes (T2D) after adjustment for multiple confounders. Methods 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 HbA_1c 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. Results we observed a U-shaped relationship between all-cause mortality and HbA_1c, with the lowest risk seen in the HbA_1c range of 6.5–7.4% and marked increased in risk with HbA_1c > 11%. The highest mortality risks of 31 and 40% were significantly associated with the lowest (<6.5%) and highest (11.5% and above) HbA_1c 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. Conclusions both low and high HbA_1c 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 HbA_1c levels around 6.5–7.4% and markedly excess risk with HbA_1c > 11% [ABSTRACT FROM AUTHOR]