By Jeff Unger, MD, FACE
Director, Unger Primary Care Concierge Medical Group, Rancho Cucamonga, CA
Dr. Unger reports no financial relationships relevant to this field of study.
SYNOPSIS: This study evaluated the sleep patterns of 64,515 women from 2005-2011. Work schedules that interfered with sleep increased the risk of type 2 diabetes.
SOURCE: Vetter C, et al. Mismatch of sleep and work timing and risk of type 2 diabetes. Diabetes Care 2015;38:1707-1713.
Patients were queried regarding their chronotype (circadian rhythm most readily defined by sleep timing) pattern using a “morningness-eveningness” questionnaire. Thirty-five percent of women classified themselves as early chronotypes, 54% as intermediates, and 11% as late chronotypes. Overall, moving from early to late chronotypes resulted in lower levels of physical activity, higher body mass indices, and more extreme sleep durations (< 5 hours and > 9 hours). Intermediate chronotype subjects who worked rotating night shifts had a 1.5 times greater risk of developing type 2 diabetes than early chronotypes who were consistent in their shift work schedules. “Circadian misalignment” interferes with sleep-wake cycles. Interestingly, late chronotype subjects who worked day shifts experienced a significant increased risk of developing type 2 diabetes, regardless of how many night shifts they worked. Interference with circadian sleep patterns appears to increase one’s risk of diabetes progression.
COMMENTARY
Sleep deprivation is a common condition in modern society. U.S. adults sleep on average 6.8 hours per night which, is 1.5 hours less than we did a century ago. Nearly 30% of adults report sleeping less than 6 hours nightly, leading some to suggest that we live in a sleep-deprived society. Adults require on average 6-8 hours of sleep nightly. Short-term sleep deprivation results in striking alterations in metabolic and endocrine function, including carbohydrate tolerance, insulin resistance, increased sympathetic tone, low levels of high-density lipoprotein cholesterol, elevated triglycerides, increased intravascular inflammation, higher risk of breast cancer, and obesity. Darukhanavala et al studied sleep pathophysiology over 13 days in 47 healthy volunteers who had a parental history of type 2 diabetes. Individuals who slept on average between 4.5 and 6 hours per night felt more daytime fatigue than those who slept 6 hours a night or longer. The short duration sleepers had more insulin resistance and higher circulating insulin levels, which allowed them to maintain normal glycemia during the study period.
This study suggests that interference with one’s normal sleep pattern increases the risk of developing type 2 diabetes. Thus, a person who normally goes to bed at 2 a.m. and gets up at 10 a.m. would develop physiologic stress if he/she must arise at 6 a.m. to work a scheduled day shift. Shift and day workers may be at higher risk of developing type 2 diabetes if they rotate to the night shift at least 3 days per month over a 10-year period.
Finally, sleep deprivation does predict type 2 diabetes onset. A cohort of men from the Massachusetts Male Aging Study who did not have diabetes at baseline were followed for 7 years. Men reporting either 5-6 hours of sleep per night or more than 8 hours of sleep per night were at a two- to three-fold increased risk of developing type 2 diabetes.
High-risk individuals (those who are overweight, physically inactive, have a positive family history, are hypertensive, or have hyperlipidemia) should be informed that the consistency in their sleep and wake cycles might mitigate their progression to diabetes.
REFERENCES
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Unger J. Diabetes Management in Primary Care. 2nd ed. Philadelphia: Lippincott, Williams & Wilkins; 2013.
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2Darukhanavala A, et al. Changes in insulin secretion and action in adults with familial risk for type 2 diabetes who curtail their sleep. Diabetes Care 2011;34:2259-2264.
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Yaggi HK, et al. Sleep duration as a risk factor for the development of type 2 diabetes. Diabetes Care 2006;29:657-661.
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O’Donnell AB, et al. The health of normally aging men: The Massachusetts Male Aging Study (1987-2004). Exp Gerontol 2004;39:975-984.
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Van Cauter E, et al. Metabolic consequences of sleep and sleep loss. Sleep Med 2008;9(Suppl. 1):S23-S28.
