May 14, 2019
2 min read

Abnormal sleep patterns raise HbA1c levels in prediabetes, untreated type 2 diabetes

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Adults with prediabetes or untreated type 2 diabetes who sleep fewer than 5 hours or more than 8 hours per night tend to have higher blood glucose levels than those who sleep between 7 and 8 hours, according to findings published in Diabetes Care.

Babak Mokhlesi

“We all sleep. There have been many studies over the last two to three decades showing relationships between sleep quality, sleep duration and either risk of developing diabetes or prediabetes or, once you have diabetes, putting your diabetes more out of control,” Babak Mokhlesi, MD, MSc, a professor of medicine at the University of Chicago, told Endocrine Today. “Our hope was to try to add to that literature with a little bit more robust methodology.”

Mokhlesi and colleagues conducted a cross-sectional study with 962 participants (mean age, 52.2 years; 45.4% women) in the RISE consortium. All participants were aged 20 to 65 years and had prediabetes (n = 704) or newly-diagnosed, untreated type 2 diabetes (n = 258). The study took place between 2013 and 2017 at four centers in Illinois, Indiana, Washington and California.

Blood samples were taken to measure HbA1c and plasma glucose, and participants also took a 75-g oral glucose tolerance test. Participants were categorized as having prediabetes (n = 704; mean age, 51.8 years; 46.6% women; mean BMI, 34.5 kg/2; mean HbA1c, 5.7%) or recent, untreated type 2 diabetes (n = 258; mean age, 53.2 years; 42.2% women; mean BMI, 35.3 kg/2; mean HbA1c, 6.1%). Sleep duration and quality were assessed via questionnaire. Sleep durations were similar for those with prediabetes and type 2 diabetes, and about one-third of each group reported sleeping 6 hours or less per night. Mean sleep duration for the entire cohort was 6.6 ± 1.3 hours per night. Shift work was reported by 23% of those with prediabetes and 28% of those with diabetes.

Among the entire cohort, participants who slept between 7 and 8 hours per night had statistically significantly lower HbA1c than those with shorter or longer sleep durations, according to researchers. Mean HbA1c levels of 5.74% (95% CI, 5.67-5.8) compared with 5.84% (95% CI, 5.74-5.93) for those who averaged fewer than 5 hours of sleep per night and 5.85% (95% CI, 5.78-5.93) for those who slept more than 8 hours per night

Sleep duration also was associated with fasting plasma glucose and BMI measures; the addition of 1 hour of sleep was associated with an increase in FPG of 0.79 mg/dL (95% CI, 0.15-1.42) and decrease in BMI of 0.3 kg/m2 (95% CI, –0.56 to –0.03). Participants who performed shift work had a mean BMI 1.32 kg/m2 higher than those who did not. Participants with higher BMI were more likely to report excessive sleepiness during the day (P = .0024) and worse sleep quality (P = .048) compared with those with lower BMI.

“If people strive to have more normal sleep duration of anywhere between 6 and a half to 7 and a half hours on average, understanding that there may be fluctuations from day to day, that might be healthier than either sleeping excessively or sleeping less than 5 hours,” Mokhlesi said. “The findings we have so far do not solve the situation yet. The next question is, if you do an intervention to help improve sleep can you make an impact? That’s where the field has to go.” – by Phil Neuffer

Disclosures: Mokhlesi reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.