Diabetes linked with 15% excess risk of death

1. In this large population-based case-control study, the excess risk of death from any cause among persons with type 2 diabetes compared to controls was approximately 15%.

2. The excess risk of death from any cause was generally worse among younger patients with diabetes and increased monotonically with higher levels of mean glycolated hemoglobin.

Evidence Rating Level: 3 (Average)

Study Rundown: The prevalence of diabetes is rapidly increasing around the globe. In this population-based study involving the Swedish National Diabetes Register (SNDR), the authors sought to determine the excess risk of death (from all causes and from CV causes) among patients with type 2 diabetes compared to controls.

In terms of overall mortality, 17.7% of patients with diabetes died from all causes over a mean follow-up of 4.6 years as compared to 14.5% controls over a mean follow-up of 4.8 years (adjusted HR, 1.15; 95% [CI] 1.14 to 1.16); the corresponding adjusted HR for CV death was 1.14. There was variation in risk across age group and glycemic control, with excess risk of death generally occurring with younger age, worse glycemic control, and greater severity of renal complications. For example, there was a significantly higher risk of death among patients with diabetes younger than 55 years of age who had a glycated hemoglobin level of 6.9% or less compared to controls, whereas patients with diabetes older than 75 years of age with the same glycemic control had a significantly decreased risk of death from any cause. The strength of the study comes from the size and depth of SNDR, which comprises more than 90% of people with diabetes in Sweden. However, the findings are limited by the cross-sectional design, which cannot exclude residual confounding factors.

Click to read the study, published today in NEJM

Relevant Reading: 10-Year follow-up of intensive glucose control in type 2 diabetes

In-Depth [case-control study]: This study was designed as a case-control study drawing patients with diabetes from the SNDR; each case was matched to five controls from the general population in Sweden based on age, sex, and county. Mean follow-up time in the diabetes group was 4.6 years compared to 4.8 years in the control group. In terms of crude mortality outcomes, the overall rate of death per 1000 person-years was 38.64 among persons with type 2 diabetes (17.7%), compared to 30.30 among controls (14.5%). Further analyses were run on Cox regression analyses, with varying levels of controlling factors. When adjusting for sex and time-updated age, country of birth, educational level, and history of coexisting medical conditions at baseline, the HR for death from any cause among persons with type 2 diabetes compared to controls was 1.15 (95%[CI] 1.14 to 1.16); for death from CV causes this HR was 1.14 (95% [CI], 1.13 to 1.15). In general, the excess risk of death was highest among younger patients compared to older patients with diabetes and increased monotonically with higher levels of time-updated mean glycolated hemoglobin. Among patients with well controlled diabetes and <55 years of age, the HR for death from any cause was 1.92 (95% [CI], 1.75 to 2.11) compared to a HR of 0.95 (95% [CI], 0.94 to 0.96) in patients older than 75 years of age. This signified a lower risk of death from any cause, among patients older than 75 years of age. In the case of patients with kidney disease, there was an increased risk of death from any cause among patients with diabetes within all age groups.

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