To address the debate on 'obesity paradox' in patients with type 2 diabetes mellitus (T2DM) by evaluating the cardiovascular and mortality risks associated with normal and overweight patients compared to obese at diagnosis of diabetes, separately for patients with and without cardiovascular disease (CVD) before diagnosis.
A retrospective study with two study cohorts with/without prior CVD (n = 10237/37272) with complete measures of body mass index (BMI) at diagnosis of T2DM from UK General Practice Research Database. Primary outcomes were long-term risks of cardiovascular events (CVEs) and all-cause mortality in patients with normal weight, overweight and obesity at diagnosis.
The mortality rates per 1000 person-years in normal weight, overweight and obese patients among patients without prior CVD were 13.1, 8.6 and 6.0, respectively, during 5 years of median follow-up. For patients with prior CVD, these estimates were 30.1, 21.1 and 15.5, respectively. Among patients without and with prior CVD, normal weight patients had 47% (hazard ratio, HR CI: 1.29, 1.69) and 30% (HR CI: 1.11, 1.53) increased mortality risk respectively compared to obese patients. In the cohort without prior CVD, compared to obese patients, those with normal body weight did not have increased CVE risk. Interactions between age, HbA1c and BMI at diagnosis were observed in both cohorts.
Adults with normal weight at the diagnosis of T2DM have significantly higher mortality risk compared to those who are obese, with significant interactions between age, BMI and HbA1c. Elevated cardiovascular risk was not observed in normal weight patients without prior CVD.