Waist circumference and grip strength and their joint relations to type 2 diabetes incidence in UK Biobank

Background Waist circumference and grip strength are each associated with type 2 diabetes (T2D) risk, but their joint associations have been less well studied. Methods We examined the separate and joint associations of waist circumference and grip strength with incident T2D among 483,578 adults aged 40–69 years (55% women) without T2D at baseline (2006–2010) from UK Biobank. Waist circumference was measured by trained staff and categorized using World Health Organization thresholds. Grip strength was assessed using a hydraulic dynamometer and categorized into age- and sex-specific tertiles. Incident T2D was ascertained through linkage to hospital inpatient records until 2022. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression, adjusting for sociodemographic, lifestyle, and clinical covariates. Results During 13.0 years of follow-up (6.3 million person-years), 30,240 participants (6.3%) developed T2D. Compared to individuals with low waist circumference (men: ≤ 94 cm, women: ≤ 80 cm), HRs were 2.11 (95% CI 2.03–2.19) for those with intermediate (men: 95–102 cm, women: 81–88 cm) and 5.48 (95% CI 5.30–5.66) for those with high waist circumference (men: > 102 cm, women: > 88 cm). Compared to individuals with high grip strength, HRs were 1.08 (95% CI 1.05–1.11) for those with intermediate and 1.35 (95% CI 1.32–1.39) for those with low grip strength. Joint analyses showed the highest risk among participants with the combination of high waist circumference and low grip strength (HR 7.68, 95% CI 7.22–8.17) compared to individuals with the combination of low waist circumference and high grip strength. Associations between waist circumference and T2D were stronger in women, whereas associations with grip strength were stronger in men. Both patterns were more pronounced among younger adults. Conclusions Waist circumference and grip strength were separately and jointly associated with T2D risk. The combination of high waist circumference and low grip strength conferred the greatest risk. Joint assessment of waist circumference and grip strength identifies individuals at particularly elevated risk and may inform preventive strategies, though formal evaluation of incremental predictive utility is needed.