Combined effect of fasting glucose and body mass index on mortality by age and sex in over 15 million adults: a cohort study

Abstract

Abstract Background We aimed to elucidate whether synergic combined association of body mass index (BMI) and fasting blood glucose (FBG) on mortality exist and to identify FBS-BMI subgroups with higher mortality according to sex and age. Methods A total of 15,149,275 Korean adults participated in health examinations during 2003–2006 and were followed up until December 2018. Hazard ratios (HRs) of 40 BMI-FBG combined groups for mortality were assessed by Cox proportional hazards models. Results During mean 13.7 years of follow-up, 1,213,401 individuals died. The association between hyperglycemia and mortality was stronger in leaner than more obese individuals and these effects were more prominent in younger than older adults. Compared with overweight (BMI 25–27.4kg/m2) normoglycemic (FBG 80–94mg/dL), age, sex-adjusted HRs of leanest (BMI <20kg/m2) normoglycemic, overweight diabetes (FBG ≥180mg/dL), and leanest diabetes were 1.66, 2.17, and 4.77, respectively. Corresponding HRs in those aged 18–44 years were 1.29, 2.59, and 11.18, respectively, while corresponding HRs in those aged 75–99 years were 1.56, 1.72, and 2.87, respectively (Figure 1). The interpretation of BMI-FBG subgroups associated with higher mortality was not straightforward. For example, prediabetes (FBG 110–125 mg/dL) with BMI 20–22.4 kg/m2 had similar or higher mortality than low diabetes (FBG 126–179 mg/dL) with BMI ≥22.5 kg/m2. In non-diabetic women aged <45 years, BMI ≥27.5 kg/m2 was associated with the highest mortality, whereas the leanest had the worst mortality in each given FBG level in other age-sex groups. Conclusions Leanness and hyperglycemia interact together to increase mortality supra-multiplicatively, especially in younger adults, while complex interaction of BMI, FBG, sex and age on mortality exist. Figure 1 Funding Acknowledgement Type of funding source: None