How Does Melatonin Affect Blood Sugar Levels?
Melatonin is primarily known as the sleep hormone. Secreted by the pineal gland, it plays a central role in regulating the circadian rhythm, the biological clock that coordinates sleep-wake cycles. However, its influence is not limited to sleep. Recent research has highlighted a close link between melatonin and glucose metabolism, revealing its potential role in regulating blood sugar levels.
Glucose metabolism relies on a delicate balance between several hormones, notably insulin and glucagon, which respectively control the decrease and increase of blood glucose. Melatonin interacts indirectly with this system by modulating cellular sensitivity to insulin and influencing its secretion by the pancreas. At night, when melatonin reaches its peak, the body adopts a metabolic mode focused on rest and repair, which results in a natural decrease in glucose tolerance.
This nighttime reduction in glucose tolerance explains why eating late in the evening can lead to a greater rise in blood sugar than the same meal taken during the day. Indeed, under the influence of melatonin, cells temporarily become less sensitive to insulin, slowing glucose uptake by tissues. In this way, melatonin helps synchronize energy metabolism with biological cycles, promoting optimal energy use during the day and limited storage at night.
Genetic studies have also shown that certain variations in melatonin receptors can influence the risk of type 2 diabetes. In some individuals, increased activity of these receptors is associated with reduced insulin secretion, which can favor a chronic elevation of blood glucose. These findings highlight that melatonin is not only a sleep hormone but also a discreet yet important actor in glycemic balance.
Moreover, disruption of the circadian rhythm, as seen in night workers or people suffering from chronic sleep disorders, is often associated with an increased risk of metabolic disorders, including insulin resistance and diabetes. Inappropriate or desynchronized melatonin production can then contribute to poor blood sugar regulation, reinforcing the importance of regular, high-quality sleep for metabolic health.
It should be noted, however, that melatonin taken as a dietary supplement may have variable effects on blood sugar depending on the individual, the dose, and the timing of intake. In some people, particularly those with existing diabetes or glucose intolerance, melatonin supplementation may slightly alter glycemic responses. Medical advice is therefore recommended before prolonged use.
In conclusion, melatonin influences blood sugar levels in an indirect but significant way by modulating insulin sensitivity, pancreatic secretion, and the temporal organization of metabolism. Far from being limited to sleep regulation, this hormone lies at the heart of interactions between the biological clock and glycemic balance. Preserving a regular sleep rhythm thus appears to be an essential strategy not only for rest, but also for preventing metabolic imbalances.
