Circadian Mechanisms, Glucose, and CV Risks in T1D

People with type 1 diabetes (T1D) are disproportionately affected by cardiovascular disease (CVD). CVD is a leading cause of death in T1D, contributing to 40% of mortality. Sleep is recognized by both the American Heart Association and the American Diabetes Association as a critical health behavior to maintain glycemic control and reduce CVD risk. Short and/or irregular sleep have been associated with reduced glycemic control and non-dipping blood pressure in T1D, both of which are predictors of CV events. Emerging data suggest that behavioral sleep interventions targeting short or irregular sleep led to improved glycemic parameters. However, little is known about the mechanism by which improving sleep duration and/or regularity improves glycemic control and reduces CV risk in T1D. The investigators and others have shown that people with T1D often experience poor sleep health, including inadequate sleep duration, sleep irregularity, and poor sleep quality. The goals of this study are to examine the mechanisms by which improving sleep regularity through behavioral sleep intervention affects glycemic control and CVD risks in T1D adults. The investigators propose to extend our previous research by conducting a mechanistic study using a sleep stability manipulation. The investigators hypothesize that sleep stability impacts glycemic control and CV outcomes by improving circadian regulation. The investigators will conduct a 4-week behavioral sleep stability intervention in 100 T1D adults with irregular sleep, utilizing a sleep pre/post design. Circadian regulation will be assessed by dim-light melatonin onset (DLMO), melatonin metabolite amplitude (overnight urinary 6-sulfatoxymelatonin levels), actigraphy-derived rest-activity rhythm, endothelial cell CLOCK gene mRNA expression, and known zeitgebers of the central and peripheral circadian clocks (light exposure, meal timing). Main glycemic outcomes will be assessed by CGM, A1C, and assessment of insulin sensitivity. Main CV outcomes will include 24h blood pressure and endothelial FMD and other secondary vascular measures (pulse wave velocity, carotid intima media thickness, and echocardiographic parameters). Sleep will be objectively recorded. All parameters will be measured at baseline and end of intervention. This proposal will advance the understanding of mechanisms by which improving sleep regularity influences glycemic control and cardiovascular risk in T1D.