Women who sleep longer over time have increased type 2 diabetes risk, study suggests

Middle-aged and older women whose sleep duration increases over time might have an increased risk of type 2 diabetes, according to a new study.
The study, conducted by the Kaiser Permanente Division of Research, California, United States is the largest ever to assess the relationship between long-term sleep duration and subsequent type 2 diabetes risk.
59,031 women were evaluated between 1986 and 2000; they were all nurses between the ages of 55 and 83.
49 per cent reported getting around seven to eight hours of sleep per night, 15 per cent consistently slept for six or fewer hours per night, while roughly the same amount slept for nine or more hours.
Five per cent reported decreases of two or more hours of sleep duration, while seven per cent reported increases of two or more hours.
Association with type 2 diabetes
3,513 women developed type 2 diabetes from the start of the study through to 2012. The women whose sleep duration increased by two or more hours had a 15 per cent greater risk of developing type 2 diabetes.
These women were also more likely to have higher BMI, poorer diet quality and do less physical activity.
Consistent sleep duration of six hours or less per night was also linked to an increased risk of type 2 diabetes, but this risk was reduced after accounting for confounding variables, such as race/ethnicity and family history of diabetes.
Study author Elizabeth Cespedes, ScD, MSc, Kaiser Permanente, told Medscape Medical News: “Our results support the message that long-term maintenance of healthy sleep duration is a pillar of health and chronic disease prevention.
“We controlled for many of these indicators of health status, including sleep apnea diagnosis, snoring, and depression, and we still saw a relationship between large increases in sleep duration and increased risk of diabetes. One possibility is that when people report longer sleep they are spending more time in bed but not necessarily sleeping more.”
Cespedes added that similar research indicated the same results for men. She also noted that for now, it is unclear whether sleeping more or less could prevent type 2 diabetes, but further studies are investigating this.
The findings were published in the online journal Diabetologia.