Association between neck circumference and incidence of type 2 diabetes in Chinese adults: a longitudinal community-based study

Although previous studies have assessed the association between baseline neck circumference (NC) and incidence of type 2 diabetes(T2D), the dynamic associations remain unclear, due to lack of longitudinal data with repeated NC measurements in large cohorts. Therefore, this study aimed to investigate the associations between dynamic changes in NC and the risk of developing T2D in a Chinese cohort. This study included 56,549 participants (mean [SD] age at baseline, 50.6 [14.3] years) from the Kailuan study who were free of T2D and have completed NC measurement at 2014 survey and at least one follow-up survey. The cumulative average NC and the percentage change in NC were calculated. The associations between NC parameters (baseline NC, cumulative average NC, and NC change) and T2D were analyzed using Cox proportional hazards models with hazard ratios (HRs) and 95% confidence intervals (CIs). Joint analyses of long-term NC parameters and body mass index or waist circumference on the risk of T2D were performed. During the mean follow-up of 5.62 years, 3,317 incident T2D cases were identified. The incidence rates of T2D by baseline NC quartiles were 12.62, 13.52, 15.34, and 20.22 per 1000 person-years, respectively. In fully adjusted model, baseline NC (HR [95%CI]: 1.24[1.12,1.37]) and cumulative average NC (HR [95%CI]: 1.51[1.36,1.67]) were positively associated with T2D risk for top vs. bottom quartile, respectively. Compared to NC maintenance group (≥ –2.5% to < 2.5%), the group with NC increased ≥ 5% had a higher risk of T2D (HR [95%CI]: 1.30 [1.16,1.46]). Significant joint effects were found between NC quartiles and body mass index (P for interaction < 0.001), especially for participants with obesity and higher baseline NC or cumulative average NC. In this prospective study, individuals with persistently high NC values were observed to be associated with higher T2D risk compared to those with consistently low NC values.