Prevalent hyperglycemia in older obese population and age-dependent convergence of obese indices: Results of a cross-sectional study of Japanese generations over the adult life span

ABSTRACT

Purpose/aim: An age-dependent decline has been observed in the association between obesity and type 2 diabetes, a major comorbidity of obesity, although the evidence is limited. Therefore, we investigated the association and the plausible underlying mechanism in a large epidemiological study. Materials and methods: We examined the association between the degree of obesity and hyperglycemia in five age groups (20–39, 40–49, 50–59, 60–69, and 70–85 years) in a cross-sectional study of 78,776 apparently healthy Japanese men and women who underwent a checkup in 2012. Hyperglycemia was defined as glycosylated hemoglobin (HbA_1c) of ≥5.7% and/or pharmacotherapy for diabetes. Results: The incidence of hyperglycemia was three times higher in the 70–85-year-old group (62%) than in the 20–39-year-old group (20%) in obese individuals (body mass index [BMI] ≥ 27.0 kg/m²). However, the incidence was 12 times higher in reference-weight individuals (21.0–22.9 kg/m²; 48% and 4%, respectively). As age increased, mean BMI and waist circumference approached certain non-obese ranges (22–24 kg/m² and 80–86 cm, respectively), even in hyperglycemic subjects. Logistic regression analysis revealed an age-dependent decline in the association between obesity and hyperglycemia, relative to that in reference-weight individuals. Conclusions: Our results confirmed the previously reported age-dependent decline in the association between obesity and hyperglycemia, although hyperglycemia was still prevalent in older obese subjects than in older reference-weight subjects. Therefore, the decline in the association may be accelerated due to an age-dependent increase in the prevalence of hyperglycemia in reference-weight individuals.

KEYWORDS:

• Age-dependent decline
• diabetes
• HbA1c
• hyperglycemia
• MHO
• MONW
• obesity
• reference-weight

Acknowledgments

KN designed the overall study and analyzed the data; KS identified eligible subjects from the database of subjects attending health checkups at Saitama Health Promotion Corporation; KN and EK discussed the results and reviewed the literature. KN wrote the manuscript and is the guarantor of the manuscript.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the article.