Does sleep matter when it comes to diabetes?
The number of diabetes patients worldwide is projected to rise from 171 million in 2000 to 366 million in 2030. Diabetes and its associated complications such as neuropathy, nephropathy, retinopathy and coronary and cerebral artery diseases have become a leading cause of chronic morbidity, mortality and increased medical costs. Older age, a family history of diabetes, overweight, obesity, central obesity, increased heart rate, elevated systolic blood pressure, elevated serum triglyceride levels, high income, history of hypertension, history of coronary heart disease, history of drinking, eating pickled foods and low educational level are also significantly connected with increased risk of prediabetes. Previous studies have shown that prediabetes is associated with poor sleep quantity and quality. Sleep plays an important role in the regulation of glucose metabolism, appetite, endocrine and immune function. Inadequate sleep has been associated with obesity, insulin resistance, type 2 diabetes, metabolic syndrome, hypertension, cardiovascular diseases and increased mortality. Prediabetes has also been suggested to be linked to sleep duration.
A cross-sectional study performed in China investigated combined effects of sleep quality and sleep duration, assessed the associations of sleep quality and impaired fasting glucose (IFG), and sleep duration and IFG. Volunteers underwent 12h overnight fasting and blood sampling for basic fasting plasma glucose (FPG) were collected. Each volunteer then completed the Pittsburgh Sleep Quality Index (PSQI). Among the excluded volunteers were those who were pregnant and others who had missing information on sleep duration or sleep quality. Statistical analysis was performed on a computer using SPSS V. 13.0. An X2 test was used to calculate the difference in proportions between groups. The proportion of volunteers with poor sleep quality was 26%, and the proportion with sleep duration < 6h was 12.5%. The proportion with sleep duration > 8h was 12.3%. The prevalence of IFG in volunteers with poor sleep quality was higher than that in volunteers with good sleep quality. Individuals with sleep duration >8h also had higher prevalence of IFG. Those with short sleep duration or long sleep duration had significantly increased risk of IFG compared to those with good sleep quality and sleep duration of 6-8h. Individuals with poor sleep quality had significantly increased risk of IFG compared with those with good sleep quality.
Another cross-sectional study conducted in Korea used surveys that consisted of a health interview, health examination and nutrition surveys. A self-administered questionnaire asked subjects how many days they usually sleep. Their answers were classified centered on their sleep duration, with short being <7 h/d, adequate 7-8h/d and long >8h/d. Blood was drawn after eight hours of fasting and glucose levels using Hitachi Automatic Analyzer 7600. Participants were classified based on their monthly income, marital status, physical activity and other classifications. Their stress recognition was also assessed. In men, 41.4% and 5.4% were short- and long-duration sleepers respectively whilst women had a 37.7% and 7.5% of short- and long-duration respectively. The overall IFG was higher in men (17.6%) than in women (10.1%) (P<0.001). In men, the prevalence of IFG among short-, adequate- and long-duration sleepers was 20.9%, 15.4% and 14.0% respectively. Women, however, had a prevalence of 11.6%, 9.8% and 6.4% respectively. Prevalence of IFG was not significantly different between sleep duration in men (P=0.074) and women (P=0.127). Short sleep duration in men <7 hours was connected with risk of IFG whereas in women shorter and longer sleep duration were not associated with risk of IFG.
In the China study, there was a combined interaction of poor sleep quality and short sleep duration on the prevalence of IFG. Also PSQI scores of volunteers with IFG were higher than those of volunteers with IFG. It did however had few limitations such as it being a cross-sectional study so no causal relationship was established between sleep quality, sleep duration and IFG. The Korean study also showed a short sleep duration in men <7-8 h/d was associated with an increased risk of IFG. There was however no association between sleep duration and IFG in women and long sleep duration was not associated with increased risk of IFG. The limitation of this study is the fact that sleep duration was assessed by self-report. Data evaluated by Rutters and colleagues from the European group for study showed a relationship and a trend for oral glucose insulin sensitivity. It suggested that men with short or long sleep durations have less insulin sensitivity compared with those with average sleep duration. The opposite was observed among women, it suggested that women with short or long durations have more insulin sensitivity compared with average sleep duration.
In conclusion it was found that short sleep duration rather than long sleep duration may increase the risk of IFG although association between short sleep duration and IFG was only seen in men.
- Although risk factors play a role in the development of type 2 diabetes, the disease is a result of interaction of genetic and environmental factors.
- Sleep plays an important role in the regulation of glucose metabolism, appetite, endocrine and immune function.
- Short sleep duration rather than long sleep duration may increase the risk of IFG, although the association between short sleep duration and IFG was only shown in men.
Lou, Peian et al. “Interaction of Sleep Quality and Sleep Duration on Impaired Fasting Glucose: A Population-Based Cross-Sectional Survey in China.” BMJ Open 4.3 (2014): e004436. PMC. Web. 7 July 2016.
Kim, Cho-Rong et al. “Association between Sleep Duration and Impaired Fasting Glucose in Korean Adults: Results from the Korean National Health and Nutrition Examination Survey 2011–2012.” Korean Journal of Family Medicine 37.1 (2016): 51–56. PMC. Web. 7 July 2016.
Wong, Patricia M. et al. “Shorter Sleep Duration Is Associated with Decreased Insulin Sensitivity in Healthy White Men.” Sleep 38.2 (2015): 223–231. PMC. Web. 7 July 2016.