# Circadian Mechanisms of Glycemic Control and Cardiovascular Risk in Adults with Type 1 Diabetes

> **NIH NIH R01** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2024 · $684,116

## Abstract

Abstract
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. Our group and others have shown that people with T1D often experience
poor sleep health, including inadequate sleep duration, sleep irregularity, and poor sleep quality. In particular,
studies from our lab have demonstrated that objectively measured sleep regularity (irregularity in sleep timing
or duration) is a strong predictor of glycemic control and insulin resistance. We have tested a behavioral sleep
intervention among adults with T1D and demonstrated improved sleep regularity and time spent in a desirable
glucose range from continuous glucose monitoring (CGM). Furthermore, we also found that poor self-reported
sleep quality in young T1D adults was associated with reduced flow mediated dilatation (FMD), a marker of
endothelial dysfunction. These observational studies demonstrate that the timing and quality of sleep are
related to key metabolic and CVD risk markers in T1D, but lack the detailed measurements and experimental
design needed to determine mechanisms. The goals of this proposal are to examine the mechanisms by which
improving sleep regularity through behavioral sleep intervention affects glycemic control and CVD risks in T1D
adults. We propose to extend our previous research by conducting a mechanistic study using a sleep stability
manipulation. We hypothesize that sleep stability impacts glycemic control and CV outcomes by improving
circadian regulation. We will conduct a 4-week behavioral sleep stability intervention in 80 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. ...

## Key facts

- **NIH application ID:** 10948651
- **Project number:** 1R01HL174738-01
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** Pamela Ann Martyn-Nemeth
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $684,116
- **Award type:** 1
- **Project period:** 2024-09-15 → 2029-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10948651

## Citation

> US National Institutes of Health, RePORTER application 10948651, Circadian Mechanisms of Glycemic Control and Cardiovascular Risk in Adults with Type 1 Diabetes (1R01HL174738-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10948651. Licensed CC0.

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