Association between delay in diabetes development and mortality in people with obesity: Up to 33 years follow-up of the prospective Swedish Obese Subjects study.

Aims: Life expectancy is reduced in people with obesity and is further reduced in those with concomitant type 2 diabetes. The aim of the study was to assess whether a 2-year delay in diabetes development influences life expectancy in people with obesity.

Materials and methods: Participants from the Swedish Obese Subjects study without diabetes at baseline and known diabetes status at the 2-year follow-up were included: bariatric surgery (n = 1471) and usual obesity care (n = 1392). Median follow-up was 26.1 years (interquartile range: 22.7-28.7 years). The Swedish Cause of Death Register, case sheets and autopsy reports were assessed to determine the direct cause of death. Analyses were adjusted for preselected risk factors: inclusion year, sex, baseline age, body mass index (BMI) and smoking.

Results: Across both study arms, 146 participants were newly diagnosed with type 2 diabetes at the 2-year examination, whereas 2717 remained diabetes-free. Most participants diagnosed with diabetes (n = 140) were from the usual care control group. During the follow-up, there were 18.3 deaths per 1000 person-years (95% confidence interval [CI]:14.1-23.9) in the group with diagnosed diabetes at the 2-year follow-up and 10.9 deaths per 1000 person-years (95% CI:10.2-11.8) in the group that remained diabetes-free (adjusted hazard ratio [HRadj] 1.60, 95% CI: 1.19-2.15, p = 0.002). The adjusted median life expectancy in the diabetes group was 3.7 years (95% CI: 1.4-6.0, p = 0.002) shorter than in the diabetes-free group. Specifically, cardiovascular mortality was higher in the group with diabetes (adj sub-hazard ratio [sub-HR] 1.74 [95% CI: 1.09-2.77], p = 0.021).

Conclusions: A 2-year delay in diabetes development may be linked to increased life expectancy, possibly due to a reduction in cardiovascular mortality. Future studies should confirm these findings.