Long-term effects of metabolically healthy obesity on the risks of diabetes, cardiovascular disease events and its mortality over 23 years in the China Daqing diabetes prevention study

Abstract

Objective To investigate the long-term effects of metabolically healthy obesity on the risks of type 2 diabetes, cardiovascular disease events, and its mortality over a 23-year follow-up. Methods Based on the results of an oral glucose tolerance test, there were 519 participants with normal glucose tolerance and 630 with newly diagnosed type 2 diabetes enrolled in 1986 and then given to assess the long-term clinical outcomes during the 23-year follow-up in Daqing. Metabolically healthy obesity was defined as the overweight and obese individuals with no metabolic abnormalities (diabetes, hypertension, hyperlipidemia). Finally, we identified 682 participants (350 with normal glucose tolerance and 332 with newly diagnosed diabetes). They were divided into five groups: 211 individuals with metabolically healthy normal weight (MHNW group), 58 with metabolically healthy overweight and obesity (MHO group), 81, 109, 223 were metabolically unhealthy overweight and obesity with hypertension (MUHO group), type 2 diabetes (MUDO group), hypertension and diabetes (MUHDO group). Incidences of type 2 diabetes, morbidity and mortality of cardiovascular disease were compared among these groups. Results Over 23 years, instead of the morbidity and mortality of cardiovascular disease, the incidence of type 2 diabetes in MHO group was two times higher than in MHNW group ( 24.1%, 12.5/1 000 person years vs 10.9%, 5.2/1 000 person years, P=0.01), with an age, sex, and smoking history-adjusted hazard ratio (HR) of 2.42 (95% CI 1.24-4.74, P=0.01). The morbidity and mortality of cardiovascular disease in the groups of overweight and obesity with metabolically unhealthy were higher than in MHNW group, and increased across the subjects with MUHO, MUDO, MUHDO (P<0.05). Conclusion Compared with metabolically healthy normal weight participants, the metabolically healthy obese group was at increased risk of type 2 diabetes but not cardiovascular disease events and its mortality. On the contrary, the overweight and obese groups with metabolic abnormalities had significant higher incidence of type 2 diabetes, morbidity and mortality of cardiovascular diseases. Key words: Metabolically healthy obesity; Diabetes mellitus, type 2; Mortality; Cardiovascular disease events