Individuals who nap during the week for 4 hours or more and have high body fat percentage and C-reactive protein (CRP) levels are at greater risk of incident type 2 diabetes, suggests a study published online April 13, 2023 in the Journal of Diabetes.¹

To examine the link between the frequency of napping during the daytime and risk of type 2 diabetes, researchers enrolled 435,342 participants without diabetes from the UK Biobank. Information about the frequency of napping at baseline was obtained via a questionnaire with participants reporting it as never or rarely (< once per week), sometimes (1–3 times per week) or usually (≥4 times per week). A total of 249 813 (57.4%) participants reporting that they did not nap or only rarely during the day were categorized as “nonnappers”; 163973 (37.7%) reported napping sometimes or “occasional nappers” while 21,556 (5.0%) reported that they napped often and were therefore grouped as “habitual nappers”.

A total of 17,592 cases of new type 2 diabetes were noted during a median follow-up period of 9.2 years. Both occasional nappers and habitual nappers were at a significantly higher risk of type 2 diabetes with odds ratio of 1.28 and 1.49 respectively. The risk was especially higher among men, participants younger than 55 years and those with obesity.

The study also aimed to explore if body fat percentage (BFP) and C-reactive protein (CRP) had any effect on this association. “A one-SD increase in CRP levels (1.1 mg/L) was associated with a 40% increase in the risk of incident T2D (95% CI: 37%–42%), and a one-SD increase in BFP (8.5%) was associated with a 69% increase in the risk of incident T2D”. The authors noted “significant additive and multiplicative interaction (relative excess risk due to interaction [RERI] = 0.490) due to interaction between napping and BFP”. Patients in the highest quartile of body fat percentage were nearly 5-times more likely to develop type 2 diabetes with a hazard ratio of 4.45. A similar result was seen for CRP (RERI = 0.266). The risk of incident type 2 diabetes was increased nearly 4-folds among habitual nappers in the highest quartile of CRP with HR of 3.66.

This study signifies the high risk of incident type 2 diabetes among participants who reported higher daytime napping frequency. High body fat percentage and CRP levels further compounded this risk suggesting a role of “adiposity and inflammation” in this interrelationship. This association was independent of the traditional risk factors for type 2 diabetes. Maintaining a healthy body fat and reducing inflammation in the body by eating an anti-inflammatory diet, regular exercise, reducing stress, and adequate good quality sleep is key to reducing the risk of diabetes.

Reference

1. Rui Zhou, et al. The association between daytime napping and risk of type 2 diabetes is modulated by inflammation and adiposity: Evidence from 435 342 UK-Biobank participants. J Diabetes. 2023 Apr 13. doi: 10.1111/1753-0407.13387.