How Do Stress, Sleep Problems Impact Type 2 Diabetes?

In individuals with type 2 diabetes (T2D), sleep problems are associated with disturbances in cortisol responses to stress, in addition to changes in diurnal cortisol output, according to a study published in Psychoneuroendocrinology.

Previous research has found sleep problems are linked with negative health outcomes, including coronary heart disease, while neuroendocrine dysfunction has also been associated with sleep problems. This disfunction may be a pathway linking sleep and ill health, researchers explain. A healthy diurnal profile of cortisol release—or raised cortisol concentrations in morning upon waking, followed by a decline over the course of the day—is associated with optimal sleep.

“Dysregulated cortisol output has been observed in people with T2D, though little is known about the links between sleep and cortisol in this population at high risk of coronary disease,” authors write.

To further investigate this association, 129 study participants completed the Jenkins sleep problems questionnaire and provided sociodemographic information. To evaluate mental stress, individuals completed 2 5-minute laboratory stress tasks including a mirror-tracing task and the Stroop color-word interference task. In addition, throughout the day researchers collected salivary cortisol at 5 time points: immediately after waking, 30 minutes after waking, at 10 am to 10:30 am, 4 pm to 4:30 pm, and at 8 pm to 8:30 pm.

Any individual previously diagnosed with coronary heart disease, inflammatory disease, allergies or mood disorders was excluded from the study.

Researchers hypothesized “sleep problems would be associated with raised evening cortisol concentrations in a naturalistic setting and with blunted cortisol responses in the laboratory environment.”

Average participant age was around 64 years, with a range between 50 and 70 years old. The majority of participants were also white males, with an average body mass index (BMI) in the obese range. Researchers found women reported greater sleep problems on average compared with men, and individuals taking diabetic medication (oral medication or insulin) were more likely to report sleep problems.

After adjusting for age, sex, marital status, education, household income, BMI and smoking, analyses revealed:

• Sleep problems were positively associated with daily cortisol area under the curve (B = 17.051, confidence interval [CI] = 6.547 to 27.554; P = .002)
• Participants reporting greater sleep problems had raised evening cortisol levels (B = 0.96, CI = 0.176 to 1.746; P = .017)
• Sleep problems were negatively associated with cortisol immediately post-task (B = -0.030, CI = -0.059 to 0.000; P = .048)
• Sleep problems were negatively associated with cortisol 45 minutes post-task (B = -0.037, CI = -0.072 to -0.002; P = .039)
• There was a trend towards significance for sleep problems and cortisol 20 minutes post-task (B = -0.028, C.I. = -0.059 to 0.004; P = .083) when adjusting for covariates

Taken together, these findings suggest those with greater sleep problems exhibit greater cortisol concentrations over the course of an ordinary day, while those who experience greater sleep problems have lower cortisol concentrations after stress.

“The results of the present study offer the possibility that sleep problems may exaggerate disturbances in evening cortisol output in people with T2D which may increase the likelihood of cardiovascular complications in this high-risk population,” researchers write. They note future research is required to confirm this conclusion.

Reference

Hackett RA, Dal Z, and Steptoe A. The relationship between sleep problems and cortisol in people with type 2 diabetes. Psychoneuroendocrinology. Published online April 23, 2020. doi:10.1016/j.psyneuen.2020.104688