Keeping time Neuroendocrine rhythms, bone, and glucose metabolism

This thesis investigates how disruption and/or restoration of human biological rhythms affects glucose metabolism, sleep, and bone metabolism.
In Part I, we focused on circadian rhythm disruptions in healthy adolescents, patients with pituitary adenoma and patients with type 2 diabetes. In a combined case-control study and randomized crossover trial in adolescents, we demonstrate that both blue-light-blocking glasses and refraining from screen use in the evening improve daytime symptoms of insufficient sleep and advance sleep onset time. In a prospective cohort study in patients with pituitary adenoma with optic chiasm compression, transsphenoidal adenoma resection did not affect the post-illumination pupil responses and sleep-wake rhythms in the first 12 months after surgery. In a case-control study, we show altered functional rhythms of the central brain clock in people with insulin resistance and type 2 diabetes compared to people with normal insulin sensitivity.
In Part II, we focused on the topic of menopause. In a cross-sectional survey, we show that two-thirds of women with type 1 diabetes perceive changes in their glucose regulation after menopause (i.e. the final menstrual period), and that changes in perceived glucose regulation are associated with the severity of reported menopausal symptoms. In a systematic review and meta-analysis, we demonstrate that postmenopausal hormone replacement therapy reduces HbA1c and fasting glucose in women with type 2 diabetes. In a randomized controlled trial in healthy postmenopausal women, restoring monthly rhythms of 17-β-estradiol resulted in higher bone formation over time compared to continuous 17-β-estradiol, while exerting neutral effects on cardiometabolic risk factors.