Insufficient sleep and insulin resistance link could explain increased male type 2 diabetes risk

A link between not getting enough sleep and insulin resistance has been identified in men which might help researchers further understand why type 2 diabetes develops.
It was already known sleep deprivation is linked with an increased risk of type 2 diabetes, but this study specifically focused on men.
A good night’s sleep is important for the body’s hormones which control a lot of important processes to regulate. Previous studies have demonstrated a decrease in the muscle-building male hormone testosterone and an increase in the stress hormone cortisol occurs when a man is sleep deprived.
Researchers from the Los Angeles Biomedical (LA BioMed) Research Institute at Harbor-UCLA Medical Center wanted to explore these findings further so they set about examining how sleep affected hormone changes.
The five-night study involved 34 healthy men in their thirties who were told what to eat and how much they slept so researchers could monitor any changes.
The first night they were allowed 10 hours of sleep, but the remaining four nights saw them restricted to only four hours.
In one part of the study, participants were given medications which limited their bodies from producing testosterone or cortisol. Then they were given fixed doses of the hormones which meant they would not experience a reduction in testosterone nor an increase in cortisol when sleep deprived.
In the second part of the crossover study, the men received inactive placebos. This meant that their bodies were free to produce hormones in response to sleep deprivation. The use of placebo meant the men had no clear knowledge when they were being treated and when they weren’t. Each intervention lasted two weeks and was randomised so that some men received the treatment first and others received the placebo first.
On the morning after the first and last night of both study sections, the men took an oral glucose tolerance test, which allowed researchers to measure their insulin resistance.
The results showed that sleep restriction increase insulin resistance in both interventions. However, the level of insulin resistance was significantly higher in the placebo group. This demonstrates that the intervention to fix the levels of cortisol and testosterone resulted in a benefit.
The study’s senior investigator Peter Y. Liu, said: “Our highly controlled sleep study showed that even one night of restricted sleep can cause insulin resistance and that we can dampen this effect by controlling levels of these two important hormones.
“Maintaining hormonal balance could prevent metabolic ill health occurring in individuals who do not get enough sleep … and understanding these hormonal mechanisms could lead to new treatments or strategies to prevent insulin resistance due to insufficient sleep.”
The findings were unveiled at ENDO 2018 in Chicago.