Relationships of neck circumference and abdominal obesity with insulin resistance considering relative handgrip strength in middle-aged and older individuals

This cross-sectional study evaluated how neck circumference (NC) influences the association between abdominal obesity (AO) and insulin resistance (IR) while considering relative handgrip strength (RHGS) in middle-aged and older people.Using data from the 2019 Korea National Health and Nutrition Examination Survey for 3804 Korean adults aged 40-80 years, AO (waist circumference [WC] ≥90 cm for men, ≥85 cm for women), large NC (sex-specific highest 5th quintile), weak RHGS (sex-specific 1st quintile of HGS/body mass index), and IR (homeostasis model assessment of IR [HOMA-IR] ≥2.5) were defined. A complex sample general linear model and logistic regression analyses were performed after adjusting for confounding factors.As NC increased, the relationship between WC and HOMA-IR increased (p for interaction <0.001). In the group with AO, large NC, or both, the adjusted odds ratio (AOR) for IR increased in the group with weak RHGS than in the group with normal RHGS. In the group with normal NC, the AOR for IR in those with AO (vs. those without AO) was 3.3 (95% confidence interval, 2.6-4.3) even after controlling for RHGS; however, the AOR was 5.3 (95% confidence interval, 2.7-10.4) in the group with large NC. These relationships of WC, NC, and RHGS with IR were comparable across sex and age groups.Large NC increased the association between AO and IR independent of RHGS and the relationships between large NC and AO and insulin resistance varied according to RHGS.