Association of diurnal patterns in salivary cortisol with type 2 diabetes in the Whitehall II study

Summary

Context:

The hypothalamic pituitary-adrenal (HPA) axis is thought to play a role in Type 2 Diabetes (T2D). However, the evidence for an association between diurnal cortisol patterns and T2D is equivocal.

Objective:

The aim was to examine the association of cortisol patterns throughout the day with T2D status in a community-dwelling population.

Design:

This was a cross-sectional study of T2D status and salivary cortisol from phase 7 (2002–2004) of the Whitehall II study, United Kingdom.

Setting:

The occupational cohort was originally recruited in 1985–1988.

Participants:

3508 white men and women including 238 participants with T2D aged 50–74 years with complete information on cortisol secretion.

Outcome Measures:

We measured diurnal cortisol (nmol/l) patterns from six saliva samples obtained over the course of a normal day: at waking, +30 min, +2.5 h, +8 h, +12 h, and bedtime. The cortisol awakening response and slope in diurnal secretion were calculated.

Results:

T2D status was associated with a flatter slope in cortisol decline across the day (B = 0.004, C.I. = 0.001 to 0.007, p = 0.014) and greater bedtime cortisol (B = 0.063, C.I. = 0.010 to 0.117, p =0.020) independent of a wide range of covariates measured at the time of cortisol assessment. There was no association between morning cortisol, the cortisol awakening response and T2D (p > 0.05).

Conclusions:

In this non-clinical population, T2D was associated with a flatter slope in cortisol levels across the day and raised bedtime cortisol values.