Lack of association between self-reported insomnia symptoms and clamp-derived insulin sensitivity in elderly men

Insomnia-related sleep disruptions, such as short and disturbed sleep, have been tied to systemic insulin resistance in young adult populations. We therefore sought to confirm these findings in a cohort of elderly men. To this aim, we utilized variables from 980 men who participated in the investigation at age 70 of the Uppsala Longitudinal Study of Adult Men. Self-reported insomnia symptoms were assessed by questions about difficulty initiating sleep, early final awakening, and regular use of hypnotics. All participants also underwent the gold-standard hyperinsulinemic-euglycemic clamp technique to assess the insulin sensitivity index (M/I). Finally, fasting blood was collected to measure free fatty acids (FFAs) and adiponectin. Differences in blood parameters between men with and those without insomnia were determined by ANCOVA, and were adjusted for lifestyle and cardio-metabolic risk factors. Our analysis yielded no differences in M/I, FFAs, and adiponectin between men with and those without insomnia symptoms. Analyses in non-diabetic and diabetic subsamples confirmed these negative findings. Our cross-sectional results therefore suggest that insomnia symptoms may have a minimal effect, if any, on measures of insulin sensitivity in elderly men. Given the observational design of our study, future studies are needed to determine whether experimental sleep manipulations influence systemic insulin sensitivity in elderly humans, as has previously been shown in young adult populations.