Sleep loss and the development of diabetes: a review of current evidence

Emerging evidence suggests that short duration of sleep and sleep disturbances increase the risk of developing diabetes. The mechanism of this presumed adverse influence of sleep loss on glucose metabolism is not well understood yet. However, in diabetes research and diabetes care, the multitude of influences of sleep and sleep loss on glucose regulation has been largely neglected so far. Here, we provide a short overview of the current epidemiological and experimental evidence for a potential contribution of sleep loss to the development of diabetes.

High plasma VEGF relates to low carbohydrate intake in patients with type 2 diabetes

OBJECTIVE

Vascular endothelial growth factor (VEGF) has been suggested to enhance glucose transport across the blood-brain barrier, thereby increasing brain glucose supply. Increased brain glucose concentration is known to suppress food intake and to decrease body mass via action on hypothalamic regulation centers. Based on the crucial role of VEGF on brain glucose supply, we hypothesized that higher VEGF concentrations are associated with lower food intake and body mass in humans.

METHODS

Intending to investigate subjects with high variance of blood glucose, we examined patients with type 2 diabetes mellitus. Our hypothesis was tested in a population-based cohort of 190 subjects with type 2 diabetes. Plasma VEGF levels in conjunction with other parameters known to modulate food intake were measured and subsequently correlated with food intake patterns at a breakfast buffet as well as with body mass.

RESULTS

We found that subjects with higher concentrations of plasma VEGF had 17% less carbohydrate intake (P=0.003) and 4.8% lower body mass (P=0.017) than those with lower VEGF concentrations. Intake of protein and fat did not correlate with VEGF concentrations. These associations of plasma VEGF were confirmed in multiple linear regression analyses controlling for several parameters interacting with food intake.

CONCLUSION

We conclude that high plasma VEGF concentrations are associated with less carbohydrate intake and lower body mass in type 2 diabetes. The role VEGF plays in facilitating glucose access to the brain represents a new aspect of food intake regulation and energy homeostasis, with relevance for diseases with body mass disturbances.

[Hydrocephalus in children]

The files of all young patients, aged from one day to 17 years, that were operated for hydrocephalus in the Service of Neurosurgery of the Citadelle Hospital from 1987 to 2003 were reviewed and analysed. Over these 16 years of practice, a shunt was placed in a total of 194 children. This paper is mainly concerned with the etiologies of hydrocephalus and the complications related to the surgical procedure.

Melatonin does not inhibit hypothalamic-pituitary-adrenal activity in waking young men

The pineal hormone melatonin is mainly secreted during night-time which, in humans, is the normal time of sleep. It has been proposed that, during this period, melatonin exerts an inhibitory influence on secretory activity of the hypothalamic-pituitary-adrenal (HPA) system, although there is little evidence for this view in humans. In blind humans, a single oral dose of melatonin at bed time suppressed nocturnal cortisol secretion. However, suppression could have been secondary to an improved sleep after melatonin in these experiments. In the present study, we examined whether melatonin exerts a similar inhibitory effect on HPA activity in waking subjects. Fourteen healthy young men were tested at bed time, but kept awake throughout the experimental epoch. Thirty minutes after oral ingestion of 5 mg melatonin, activity of the HPA-system was stimulated through a standard insulin-induced hypoglycaemia. Adrenocorticotrophin hormone and cortisol concentrations under basal conditions before insulin injection, as well as in response to insulin-induced hypoglycaemia, were almost identical for the melatonin and placebo control conditions (P > 0.5). However, melatonin increased plasma prolactin concentrations (P < 0.01) and reduced systolic blood pressure in the time interval following hypoglycaemia (P < 0.05). Based on a review of the literature and our results, we conclude that melatonin per se has no substantially suppressing effect on HPA secretory activity, although such an effect can be gated by sleep-related processes.

Serum adiponectin concentrations during a 72-hour fast in over- and normal-weight humans

OBJECTIVE

Adiponectin is currently considered an important link between obesity and insulin resistance, since circulating levels of this insulin sensitizing hormone have consistently been found to be reduced in obese subjects. However, until now it is not known how the secretion of adiponectin is regulated in response to acute metabolic changes. Here, we assessed the influence of complete fasting for 72 h on serum adiponectin levels.

DESIGN

Between group comparison of repeated measurements.

SUBJECTS

In total, 18 normal-weight (mean+/-s.e.m. BMI: 22.2+/-0.4 kg/m(2); age: 39.2+/-4.4 y) and nine over-weight (BMI: 33.2+/-1.8 kg/m(2); age: 36.9+/-4.5 y) subjects.

MEASUREMENTS

Serum adiponectin levels were measured every 4 h during a 72-h fasting period. Additionally, concentrations of plasma glucose and serum insulin and leptin were assessed at the beginning and in the end of the fasting experiment. Insulin resistance was estimated using the homeostasis model assessment (HOMA).

RESULTS

While concentrations of glucose, insulin, and leptin decreased across the fasting period by 31.0, 33.1 and 60.0%, respectively (all P<0.005), adiponectin levels remained unchanged (P=0.817). Overall, over-weight subjects exhibited slightly lower adiponectin levels than normal-weight subjects (P=0.092), but there was no difference in the time course of adiponectin levels during fasting between these two groups (P=0.970). Although, averaged adiponectin levels before and after fasting did not systematically differ, individual changes in adiponectin levels across fasting displayed a slight but significant inverse correlation with changes in plasma glucose concentration (r=-0.42, P=0.03).

DISCUSSION

The data show that serum adiponectin concentrations remain remarkably stable during 72 h of fasting in normal- and over-weight subjects. Thus, adiponectin appears to reflect primarily long-term changes in body weight with little evidence for a dependence on short-term regulatory influences.