Impact of longer diabetes duration and lower estimated glomerular filtration rate on cardiovascular complications and mortality: A nationwide population-based study.

Background: Decreased renal function is a well-known risk factor for cardiovascular diseases (CVD) and death. However, the impact of diabetes duration and the glomerular filtration rate (GFR) on cardiovascular complications in patients with type 2 diabetes has not been well studied.

Aim: To investigate the complex impact of longer diabetes duration and GFR on CVD and mortality.

Methods: Subjects with diabetes age ≥ 20 years, who underwent health check-ups from 2015 to 2016 were identified in the Korean National Health Insurance Service database. Based on diabetes duration, subjects were grouped into new-onset, < 5 years, 5-9 years, or ≥ 10 years. The new-onset diabetes group [estimated GFR (eGFR): ≥ 90 mL/min/1.73 m²] was the reference group. A Cox proportional hazards model adjusted for potential confounders was used to estimate the risk for myocardial infarction (MI), ischemic stroke (IS), and mortality.

Results: During a 3.9-year follow-up of 2105228 patients, 36003 (1.7%) MIs, 46496 (2.2%) ISs, and 73549 (3.5%) deaths were documented. Both longer diabetes duration and lower eGFR were independently associated with higher risks of MI, IS, and mortality, which were further amplified when these factors coexisted. Even patients with new-onset diabetes had elevated MI and IS risk at mildly reduced eGFR (60-90 mL/min/1.73 m²). Mortality risk rose appreciably once eGFR declined below 60 mL/min/1.73 m², particularly in those with longer diabetes duration. eGFR ≥ 90 mL/min/1.73 m² subgroups had higher death risk than eGFR 60-90 mL/min/1.73 m² subgroups regardless of diabetic duration.

Conclusion: Increasing diabetes duration and decreasing eGFR are associated with increased risk of MI, IS, and mortality. For cardiovascular risk estimation, diabetes duration should be considered an important risk factor.