Joint impact of modifiable lifestyle behaviors on glycemic control and insulin resistance in patients with type 2 diabetes: the Fukuoka Diabetes Registry

Aims: Little is known about the combined effects of unhealthy lifestyle behaviors on glycemia. The objective of this study was to examine the association between combined modifiable lifestyle and glycemic control, as well as markers of insulin resistance and secretion. Patients and methods: In total, 4,870 patients with type 2 diabetes were sorted by lifestyle scores. Scores were determined by summing the number of unhealthy lifestyle factors that showed a significant association with hemoglobin A_1c (HbA_1c) (current smoking, decreased dietary fiber intake, eating quickly, inadequate sleep duration, and obesity). The associations between lifestyle score and hemoglobin A_1c (HbA_1c), homeostasis model assessment of insulin resistance (HOMA2-IR), and β-cell function (HOMA2-%B) were cross-sectionally analyzed. Results: HbA_1c increased progressively with increases in lifestyle score (p for trend <0.001). Mean HbA_1c was 0.48% (95% confidence intervals 0.34–0.63) higher in patients with scores of four to five than in those with zero scores. HOMA2-IR and high-sensitivity C-reactive protein also revealed a similar tendency, but adiponectin showed an inverse association. However, these graded tendencies were not observed for HOMA2-%B. Additionally, lower HOMA2-%B levels enhanced the effects of lifestyle score on glycemia. Increases in HbA_1c per point in the lifestyle score in patients with the lowest and highest quartiles of HOMA2-%B were 0.25% (0.18–0.32) and 0.10% (0.06–0.15), respectively (p for interaction <0.001). Conclusions: Accumulation of unhealthy lifestyle factors was dose-dependently associated with poor glycemic control, which may be modified by insulin secretory capacity.