Melatonin is a hormone that helps with the body’s circadian rhythm and sleep. A mutation in the melatonin hormone may increase a person’s risk of type 2 diabetes and high blood sugar.

Type 2 diabetes is a chronic condition in which blood sugar, or blood glucose, levels are too high. Blood sugar is the main source of energy for the body’s cells. The body uses chemical reactions to transform food into glucose and energy in a process known as metabolism.

The body uses the hormone insulin to move glucose from the blood into cells. Cells sometimes become less sensitive to insulin than usual, known as insulin resistance. If the body cannot produce enough insulin to meet the cells’ needs, type 2 diabetes develops.

Some 2022 research suggests that the hormone melatonin may also affect glucose metabolism. People who have certain mutations in a gene that codes for melatonin receptor 1b (MTNR1b) have an increased risk of high blood sugar and type 2 diabetes.

Melatonin regulates the body’s circadian rhythm, which causes body functions to become more or less active at different times of day. Some people take melatonin supplements to help them sleep.

Scientists believe that melatonin supplements might also have benefits for managing blood sugar in type 2 diabetes, but more research is necessary.

Scientists are still studying how melatonin affects blood sugar levels.

A 2022 review of research on melatonin and glucose metabolism reported mixed results. Some studies note that increased melatonin levels may help reduce insulin resistance or keep blood sugar within an optimal range, but other studies have not found these results.

Research from 2019 found evidence that melatonin stimulates the production of both insulin and glucagon in the pancreas. Insulin reduces sugar levels, and glucagon stops levels from falling too low. The body needs an appropriate balance of both hormones to keep blood sugar within a safe range.

Some research on animals suggests that melatonin may reduce insulin secretion in the short run but increase it in the long run. Melatonin may promote the healing and growth of pancreatic beta-cells, which secrete insulin.

Different doses of melatonin may affect glucose metabolism differently.

The timing of food intake may also influence the effects of melatonin on glucose metabolism. A 2020 commentary suggests that eating when melatonin levels are high might negatively affect glucose management, and avoiding food when melatonin is high might improve glucose management. Melatonin tends to be naturally high at night.

It is possible that melatonin may affect glucose metabolism differently from person to person, depending on whether they carry certain mutations in the MTNR1b gene.

Many studies on melatonin and glucose metabolism have used animals, such as rats or mice, and the results may not translate well to humans.

More research is necessary to understand how melatonin affects glucose metabolism in different groups of people.

The potential benefits of melatonin for type 2 diabetes are unclear, with studies reporting mixed results.

The body naturally produces melatonin, but melatonin supplements are also available.

A 2021 review examined the effects of taking melatonin supplements daily before bedtime among healthy adults and those with metabolic conditions such as diabetes.

Melatonin supplementation did not significantly affect fasting glucose levels or HbA1c, which measures average blood sugar over previous months. However, it did appear to reduce fasting insulin levels and showed promise for reducing insulin resistance.

Another 2021 review examined how taking melatonin supplements affected diabetes parameters in adults. Roughly half of the 16 studies in this review linked melatonin supplements to improvements in diabetes parameters, including improvements in fasting glucose and HbA1c levels and reduced insulin resistance.

These review findings suggest that melatonin supplementation may have benefits for managing type 2 diabetes, but they report mixed results. More research is necessary.

Some research suggests that melatonin supplements may have other health benefits.

Melatonin supplements may help reduce inflammation, triglycerides, and total cholesterol levels. This might reduce the risk of certain health conditions that are more common in people with type 2 diabetes, such as heart disease.

Melatonin supplements may also improve sleep, which is a common reason people take them. Getting enough sleep is important for supporting glucose management and overall health.

According to the National Center for Complementary and Integrative Health (NCCIH), there is not enough information about the potential side effects of melatonin to have a clear understanding of its long-term safety.

Studies on melatonin generally report only mild side effects, such as:

  • drowsiness
  • dizziness
  • headaches
  • agitation
  • nausea

More research is necessary on the long-term risks of melatonin supplements, including for people with type 2 diabetes. More research is also required to identify the safest doses, formulations, and timing of melatonin supplements for people with type 2 diabetes.

Some researchers theorize that eating when melatonin levels are high may worsen glucose management rather than improve it. This suggests the timing of melatonin supplements might affect the potential risks versus benefits.

It is also possible that melatonin supplements may carry more risks or fewer benefits for people who have certain genetic mutations in the MTNR1b gene.

People with type 2 diabetes should talk with a doctor to learn more about the potential risks.

Taking melatonin supplements might lower blood sugar levels. If someone takes melatonin along with glucose-lowering medications, it might cause their blood sugar to drop too low, known as hypoglycemia.

Melatonin can cause drowsiness, which may be more severe if someone also takes other medications or supplements that cause drowsiness. Examples of these medications include:

  • insomnia medications, such as zaleplon (Sonata), zolpidem (Ambien), or zopiclone (Zimovane)
  • certain antidepressant, anti-anxiety, and antipsychotic medications
  • nonsteroidal anti-inflammatory drugs
  • opioids

Melatonin may also have a blood-thinning effect. It may interact with blood thinners or blood pressure medication.

A person should speak with a doctor or pharmacist about potential drug interactions before taking melatonin supplements. They can also discuss any other medications, supplements, or other treatments they are taking.

Questions remain about the potential benefits and risks of melatonin supplements for people with type 2 diabetes.

Individuals should seek medical advice before taking melatonin supplements. A healthcare professional can explain the potential benefits, risks, and drug interactions.

Doctors may also recommend other strategies to manage type 2 diabetes or other health concerns, such as sleep difficulties. A combination of lifestyle changes, medications, or other treatments are common recommendations.

Melatonin is a hormone that regulates the body’s circadian rhythm. It appears to play a role in glucose metabolism, but researchers are still learning how it affects insulin sensitivity and blood sugar levels.

Some research suggests that melatonin supplements may have certain benefits for managing type 2 diabetes, but other findings report mixed results.

More research is necessary to understand the potential benefits and risks of melatonin supplementation for managing type 2 diabetes, as well as the optimal dosing, formulation, and timing of supplementation.

People with type 2 diabetes who are interested in taking melatonin supplements should seek medical advice first. Melatonin might interact with other medications or supplements. A doctor can help manage the risk of side effects and drug interactions.

A doctor can also recommend other strategies to manage type 2 diabetes or other health issues. They may recommend lifestyle changes, medications, or other treatments.