A Preliminary Look at the Effect of Light Exposure on Blood Glucose Levels of Overweight and Obese Teens

Purpose: Teens experience a puberty-driven delay in their circadian clock due to a mismatch in their internal and social clocks that increases their risk of adverse health outcomes. Disruption to the circadian system from ill-timed light exposure before bedtime and reduced melatonin levels produces adverse changes in glucose control and increases Type 2 Diabetes Mellitus (T2DM) risk. As such, teens may be more susceptible to developing T2DM. This study sought to provide better insight into the relationship between light exposure around the sleep period and risk of developing T2DM in this vulnerable and understudied population. We proposed that light levels would be positively associated with HbA1c levels in teens during the two hours before bedtime and during the sleep period. Methods: Current analyses utilized baseline data from a 13-week pilot intervention study (PI: Roane) that examined the impact of a circadian-conscious intervention on T2DM risk. Teens and caregivers provided informed consent/assent. HbA1c levels (mmol/mol) were collected via finger prick. Teens followed a “typical” self-selected sleep schedule for 1-week while wearing a wrist actigraph (AMI MicroMotion Logger) to capture 24-hour sleep and light data. BMI %tile was calculated from in-lab measured height and weight. Mean lux, percent time above 20 lux, minimum lux, and maximum lux were calculated for the two hours pre-bedtime and during the sleep period. Correlation analyses were run to examine the association between light exposure and HbA1c due to small sample size. Results: Teens (n=7) were age 16 years, 57% female, and 57% Hispanic with low to moderate T2DM risk. Mean BMI %tile was 97th, HbA1c was 5.4, and 57% exhibited Acanthosis Nigricans. Mean sleep period duration was 496 minutes (mean sleep duration during this period = 410 minutes). Correlation analyses were not significant; however, visual inspection showed sex-differences in HbA1c levels and different patterns in how light exposure during these two crucial periods may relate to HbA1c. Conclusion: These pilot findings did not confirm an association between light exposure (lux) and HbA1c levels (mmol/mol) in obese and overweight teenagers. Findings were limited by a sample that was small in size and low in T2DM risk. Suggested sex differences in these data combined with documented sex differences in the literature support further examining sex differences in a larger sample with more diverse T2DM risk.