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Sleep is Sweeter Than We Think

Jul 30, 2019
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Amber Satz, PharmD Candidate, LECOM School of Pharmacy

A recent cross-sectional, cohort study found that too little or too much sleep is associated with higher HbA1c.

According to a recent cohort study, published in ADA Diabetes Care, self-reported short and long sleep times were associated with glycemic values out of normal range in patients with prediabetes and recently diagnosed, untreated patients with diabetes. Also, short sleep times and shift work patterns were found to be associated with higher BMI values within the same population. It is important to interview patients regarding their sleep time and sleep quality as a part of examining the patient as a whole, especially upon observing signs of potential prediabetes or diabetes. Sleep, among many other lifestyle factors, may impact the progression of diabetes including the efficacy of treatment.

Over the last decade, prospective epidemiologic studies have found an association with sleep disturbances such as short and long sleep duration, poor sleep quality, obstructive sleep apnea, and circadian misalignment, and type 2 diabetes. Few studies have examined whether sleep quality or circadian misalignment are associated with uncontrolled glycemic values, independent of BMI and physical activity. The association of sleep disturbances and glycemic control in patients with prediabetes has not been explored.

The objective of this cohort study was to examine the relationship between self-reported sleep times, sleep quality, and circadian misalignment (social jet lag, late chronotype, or shift-work) with glycemic control, BMI, and blood pressure in adults with type 2 diabetes, or prediabetes. A cross-sectional analysis of data from the screening phase of the Restoring Insulin Secretion (RISE) consortium of randomized controlled trials was performed. Men (55%) and women (45%), aged 20-65 years old, with obesity or overweight were recruited from four adult health centers across the United States. All patients underwent a fasting plasma glucose measurement, HbA1c measurement and 75-g oral glucose tolerance test (OGTT) including a plasma glucose measurement at 2 hours. Patients must have met the American Diabetes Association definition of prediabetes (fasting plasma glucose 100-125 mg/dL, 2-h plasma glucose 140-199 md/dL, or HbA1c 5.7-6.4%) as well as have been recently diagnosed within one year. Untreated participants with existing type 2 diabetes, defined by the American Diabetes Association, (fasting plasma glucose 126 mg/dL, 2-h plasma glucose  200 mg/dL, or HbA1c  6.5%) were also included. Weight and blood pressure measurements were taken. To assess sleep, The Pittsburgh Sleep Quality Index (PSQI) questionnaire, The Berlin Questionnaire, and the Epsworth Sleepiness Scale (ESS) were used.

Of the 962 participants, 704 had prediabetes and 258 had diabetes. After adjustment for age, sex, race/ethnicity, and BMI, those reporting an average of <5 hours and >8 hours of sleep daily had significantly higher HbA1c values compared to those with 7-8 hours of sleep. Fasting glucose was directly associated with sleep duration. BMI was inversely associated with sleep duration and sleep quality, and  directly associated with excessive daytime sleepiness. 

This study serves as a good background for understanding the relationship sleep has with control of diabetes and other important metabolic values. The cohort had a significant amount of ethnically diverse participants, with a near even divide between men and women, supporting its generalizability. Important factors that may impact participants’ BMI and glycemic control such as diet, meal timing and physical activity were not accounted for in this study. Further studies should be conducted to make stronger conclusions regarding the impact of sleep on glycemic control.

 Practice Pearls:

  • A recent cross-sectional, cohort study displays an association between poor glycemic control and sleep times <5 hours and >8 hours per day in patients with prediabetes and untreated diabetes.
  •  It is important to counsel patients on the importance of sleep hygiene as the effects on health are tremendous.
  • Further studies need to be conducted to determine causality between sleep patterns and glycemic control.


References: Sleep Associated with Higher HbA1c:

Mokhlesi, Babak, et al, “Association of Self-Reported Sleep and Circadian Measures With Glycemia in Adults With Prediabetes or Recently Diagnosed Untreated Type 2 Diabetes.” Diabetes Care, vol. 42, no. 7, 2019, pp. 1326–1332., doi:10.2337/dc19-0298.]


Amber Satz, PharmD Candidate, LECOM School of Pharmacy