Introduction
Metformin is a medication that is commonly prescribed to treat type 2 diabetes. It works by reducing glucose production in the liver and improving the body’s sensitivity to insulin. While metformin is generally well-tolerated, one of the potential side effects is fatigue or tiredness. In this article, we will explore the connection between metformin and fatigue and provide an overview of the scientific research on this topic.
How does metformin work?
Metformin belongs to a class of medications called biguanides. It works in three main ways:
- Reduces the amount of glucose released by the liver
- Increases the sensitivity of muscle and fat cells to insulin
- Delays the absorption of glucose from the intestines
Together, these actions work to lower blood sugar levels in people with type 2 diabetes. By improving insulin sensitivity and reducing excess glucose production, metformin enables insulin to work more effectively.
What causes fatigue as a side effect?
While the exact mechanisms are still being investigated, there are a few possible reasons why metformin may cause fatigue in some individuals:
- Metformin can lead to vitamin B12 deficiency, which can cause anemia and tiredness.
- It may alter mitochondrial function and ATP production in cells, affecting cellular energy.
- Gastrointestinal side effects like nausea and diarrhea can result in dehydration and electrolyte imbalances.
- Metformin may influence serotonin, dopamine, and melanocortin signaling in the brain, which regulate sleep and wakefulness.
The accumulation of these effects over time is likely what leads to metformin-associated fatigue in susceptible individuals.
How common is fatigue with metformin treatment?
Estimates of how often fatigue occurs with metformin vary widely based on the population studied:
- 10-15% of metformin users report fatigue in most studies.
- Up to a third of elderly metformin users may experience tiredness.
- Fatigue is one of the most common side effects leading to metformin discontinuation.
- Women may be more susceptible to metformin-related fatigue than men.
So while not everyone experiences fatigue from taking metformin, it is a common enough occurrence that patients should be aware of this potential side effect.
Does the fatigue diminish over time?
For many people, the fatigue they experience when first starting metformin does tend to improve over days or weeks of continued treatment. There are a few reasons why the tiredness may lessen over time:
- The body adjusts to the medication and gastrointestinal side effects subside.
- Dehydration and electrolyte imbalances level out.
- Prescribers adjust the dose to reduce adverse effects.
- Patients develop a tolerance to the drug’s effects.
However, fatigue persists long-term in some metformin users. This may be due to continued vitamin B12 deficiency, mitochondrial effects, or individual differences in medication tolerance. Ongoing fatigue may necessitate a change in diabetes treatment approach for some patients.
How long does metformin fatigue last?
There is no set timeline for how long metformin-related fatigue lasts. Some patients report feeling tired for only the first few weeks of starting treatment. For others, the fatigue may come and go over months or years of using metformin.
According to clinical studies, the timeline of metformin fatigue can vary considerably:
- In one study, mild fatigue resolved within 8 weeks for most participants.
- Up to 6 months may be required to improve metformin tolerance in some individuals.
- Fatigue lasting longer than 6 months is unlikely to resolve without treatment changes.
- Persistent fatigue and tiredness for years has been reported anecdotally.
The development of vitamin B12 deficiency as a result of metformin treatment can also lead to fatigue. This tends to be a gradual process that worsens over months to years if B12 levels are not monitored and supplemented.
Tips for alleviating metformin fatigue
If metformin is causing intolerable fatigue or tiredness, there are some steps that may help provide relief:
- Ask your doctor about reducing your metformin dose gradually.
- Take the medication with food to minimize GI side effects.
- Stay well hydrated by drinking plenty of water.
- Be sure you are getting enough B vitamins and iron in your diet.
- Consider taking a B12 supplement if deficiency is likely.
- Exercise regularly to increase energy levels.
- Allow time for your body to adjust to the medication.
For severe or persistent fatigue, your doctor may recommend switching diabetes medications entirely. Alternative medications like DPP-4 inhibitors, SGLT2 inhibitors, GLP-1 agonists, or insulin do not list fatigue as a common side effect.
The bottom line
In summary, fatigue and tiredness are common complaints from metformin users, reported in up to 15-30% of patients. The mechanisms linking metformin to fatigue likely involve vitamin B12 deficiency, mitochondrial effects, GI side effects, and impacts on neurotransmitters.
For many individuals, metformin fatigue resolves within weeks to months as the body acclimates to the drug. But others deal with persistent tiredness for longer periods. Monitoring vitamin B12 levels, staying hydrated, exercising, and adjusting the dosage can help manage fatigue. If symptoms remain problematic, switching to an alternative medication may be warranted. Working closely with your healthcare provider can help optimize diabetes treatment while minimizing unpleasant side effects like fatigue.
Frequently Asked Questions
Does metformin make you tired and sleepy?
Yes, fatigue and sleepiness are common side effects of metformin for some users. Metformin may directly affect cellular energy production and neurotransmitters involved in sleep/wake regulation. Fatigue is most likely to occur when first starting metformin but can persist long-term in some individuals.
Why do I feel weak and tired on metformin?
Metformin can cause feelings of weakness and fatigue through several mechanisms. It may lower vitamin B12 levels leading to anemia. Metformin also seems to disrupt mitochondrial function and cellular energy metabolism. These effects likely contribute to muscle weakness and lack of energy. GI side effects can also worsen fatigue.
How can I stop feeling tired on metformin?
If metformin makes you feel constantly tired, some options include lowering the dose, taking it with food, staying hydrated, exercising regularly, allowing time to adjust, supplementing B12, and ultimately switching to an alternative diabetes medication if fatigue remains problematic. Your doctor can help adjust treatment accordingly.
Does metformin fatigue go away?
Metformin fatigue often resolves within weeks to months as the body gets used to the medication, but it can persist long-term for some individuals. Mild fatigue tends to improve more quickly than severe tiredness. Changing the dosage or timing may help. For recalcitrant fatigue, switching diabetes medications may be preferable.
Should metformin be taken at night or morning?
Most doctors recommend taking metformin with a meal in the morning or evening to reduce gastrointestinal side effects. Taking it at night may help minimize fatigue during the day. However, metformin can also cause insomnia in some people, so morning dosing may be better if nighttime sleep disruption occurs.
Conclusion
Metformin is an effective diabetes medication that commonly causes fatigue and tiredness as a side effect. The tiredness tends to improve over time for many patients as the body adjusts to the drug. However, ongoing fatigue lasting months to years is not uncommon and can negatively impact quality of life. Monitoring for vitamin B12 deficiency, staying hydrated, exercising, adjusting the dose, switching timing, and using alternative medications can help manage metformin fatigue under a doctor’s supervision. While metformin works well for controlling blood sugar for most people with type 2 diabetes, fatigue is a potential trade-off that should be discussed and addressed appropriately.