Shorter sleep durations increase risk for type 2 diabetes, regardless of diet quality

Key takeaways:

• Sleep durations of 5 hours or less increased the risk for type 2 diabetes.
• Obstructive sleep apnea may limit the impact of a healthy diet on diabetes risk, researchers noted.

Shorter sleep durations increased the risk for developing type 2 diabetes, even among those with healthy eating habits, research showed.

According to Diana Aline Nôga, PhD, a researcher from Uppsala University in Sweden, and colleagues, although it has been established that a healthy dietary pattern can help reduce the risk for type 2 diabetes, “the extent to which adherence to such a diet can mitigate the elevated risk of [type 2 diabetes] associated with chronic short sleep duration is less clear.”

“This area of research is particularly challenging due to the tendency of short sleep to promote unhealthy food choices,” they wrote in JAMA Network Open.

The researchers hypothesized that a healthy dietary pattern would ultimately reduce the risk for diabetes among those with shorter sleep durations.

Nôga and colleagues analyzed data from 247,867 participants in the U.K. Biobank (mean age, 55 years; 52.3% women) who were categorized into four sleep duration groups: normal (7-8 hours per day), mild short (6 hours per day), moderate short (5 hours per day) and extreme short (3-4 hours per day).

They also assessed participants’ dietary patterns, which were ranked based on a score of 0, or unhealthiest, to 5, or healthiest.

During a median follow-up of 12.5 years, 3.2% of participants were diagnosed with type 2 diabetes.

The researchers found that individuals who slept 5 hours (adjusted HR = 1.16; 95% CI, 1.05-1.28) and those who slept between 3 to 4 hours (aHR = 1.41; 95% CI, 1.19-1.68) had a greater risk for developing type 2 diabetes vs. individuals who reported a sleep duration of 7 to 8 hours.

Meanwhile, individuals with a healthy diet score of 4 (HR = 0.82; 95% CI, 0.7-0.96) or 5 (HR = 0.75; 95% CI, 0.63-0.88) were less likely to develop type 2 diabetes compared with those with a healthy diet score of 0.

However, contrary to Nôga and colleagues’ hypothesis, the association between shorter sleep duration and type 2 diabetes remained even among individuals who followed a healthy diet in both the adjusted and unadjusted analyses.

There were several study limitations, the researchers said. For example, they could not determine whether certain types of diets, such as the Mediterranean diet, could influence diabetes risk in individuals with short sleep durations.

“Additionally, there may be specific macronutrients or micronutrients, not explored in this study, that could more effectively counteract the adverse metabolic effects induced by sleep loss,” they wrote.

Nôga and colleagues noted that obstructive sleep apnea is known to heighten the risk of insulin resistance and type 2 diabetes, which could explain the findings.

“Given this possibility, the efficacy of healthy dietary patterns in mitigating the adverse effects of short sleep on glucose metabolism may be limited if obstructive sleep apnea is coexistent,” they wrote.