Associated risk factors and their interactions with type 2 diabetes among the elderly with prediabetes in rural areas of Yiyang City: A nested case–control study

To explore associated risk factors and their interactions with type 2 diabetes (T2DM) among the elderly with prediabetes in rural areas in China. A nested case–control study was conducted in a fixed cohort to identify the risk factors for T2DM among the elderly with prediabetes in rural areas of Yiyang City in China. A total of 37 elderly with T2DM were included in the cases group and 111 elderly subjects with prediabetes were matched in the control group. Data related to sociodemographic characteristics, lifestyle behavior, and anthropometric variables were collected by trained staff using standard tools. The risk factors for T2DM were determined using conditional logistic regression analysis, and their additive interactions were also explored. Multivariable conditional logistic regression analysis results showed that overweight/obesity (odds ratio [OR] = 4.80, 95% confidence interval [CI]: 1.20–12.28), family history of diabetes (OR = 3.63, 95% CI: 1.03–12.81), physically inactive (OR = 3.08, 95% CI: 1.14–8.30), high waist-to-hip ratio (WHR) (OR = 3.15, 95% CI: 1.27–7.80), and inadequate diabetes-specific health literacy (DSHL) (OR = 3.92, 95% CI: 1.14–13.48) increased the risk for T2DM. Additive interactions for T2DM were observed between a family history of diabetes and high WHR with a relative excess risk of interaction (RERI) of 10.02 (95% CI: 4.25, 15.78), and between high WHR and overweight or obesity, with an RERI of 3.90 (95% CI: 0.36, 7.44). The independent risk factors for T2DM are overweight or obesity, high WHR, family history of diabetes, physically inactive, and inadequate DSHL. High WHR as a risk factor for T2DM has additive interactions with family history of diabetes and overweight or obesity.