Is Fasting Safe for Patients with Type 2 Diabetes?


This month, able-bodied Muslims around the world are fasting from dawn until dusk in observance of the holy month of Ramadan.

This month, able-bodied Muslims around the world are fasting from dawn until dusk in observance of the holy month of Ramadan. For those living in North America and parts of Europe, this means abstaining from food and drink for 16 to 19 hours every day for the next lunar month.

Those with medical conditions are excused from fasting, but some still choose to follow the religious practice. Therefore, providing safe and effective pharmacotherapy recommendations for patients who are fasting, particularly those with type 2 diabetes, can be challenging.

Understanding the risks associated with fasting and considerations for pharmacological and nonpharmacological interventions can help guide health care providers in caring for those with type 2 diabetes who are fasting.

Associated Risks


The EPIDIAR study observed a 7.5-fold increase in hypoglycemic events (blood glucose <60 mg/dL) in patients with type 2 diabetes who were fasting during the month of Ramadan. Hypoglycemia in any patient is concerning, but with the added variable of fasting, it’s important for health care providers to educate patients on the signs and symptoms of hypoglycemia, as well as the medical necessary to break their fast when they occur.


A 5-fold increase in severe hyperglycemia during Ramadan was seen in the EPIDIAR study. Commonly, hyperglycemia in fasting patients with type 2 diabetes occurs secondary to preemptive dose reductions of diabetes medications, either by physicians or self-management by patients, in an attempt to avoid hypoglycemia.

Although patients’ glucose levels may be controlled or lower during daylight hours while fasting, acute elevations may occur in those consuming high-carbohydrate food sources when breaking their fast and immediately before starting their fast.


Prolonged hours without fluids combined with the hot summer months increases the risk of dehydration in fasting patients. Additionally, hyperglycemia can lead to an osmotic diuresis, further exacerbating the fluid balance.

In severe cases, hypovolemia may lead to syncope or falls. It’s important for patients to be mindful of this and ensure adequate fluid intake throughout the night hours (at least 2 glasses of water before each meal). Patients taking diuretics may require a dose reduction.

Pharmacological Considerations


Because of the low risk of hypoglycemia with metformin, most patients treated with metformin alone can safely continue to fast. It’s recommended for patients to take two-thirds of their total daily metformin dose with their sunset meal, and one-third with their predawn meal.


Sulfonylureas generally aren’t recommended for fasting patients because of their inherent risk of hypoglycemia. If cost or medication access limits a different drug class, second-generation sulfonylureas (eg, glimepiride, glipizide) can be considered.

Once-daily regimens should be given with the sunset meal. Those taking twice-daily regimens can reduce their morning (predawn) dose by half and resume their evening dose with their sunset meal.

Incretin-Based Therapies

Given alone, glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidylpeptidase-4 (DPP-4) inhibitors cause less hypoglycemia than other conventional therapies and provide a safe treatment option for fasting patients. If possible, patients taking sulfonylureas can be switched to an incretin-based therapy in anticipation of the fasting month.

Of note, once-weekly exenatide should be avoided due to the hypoglycemic risk.

Long-Acting Insulin

In patients taking insulin glargine and insulin detemir, it’s generally recommended to decrease the insulin dose by 20% to reduce the risk of hypoglycemia. Doses should be taken at night with the patient’s largest sunset meal.

Nonpharmacological Considerations

Food Consumption

After a long day of abstaining from food and water, it’s common for fasting patients to ingest large amounts of carbohydrates and high-fat foods with their sunset meal. To achieve more controlled glucose and insulin levels throughout the day, it would be more advisable to eat simple carbohydrates at the sunset meal and eat complex carbohydrates with the predawn meal.


Physical activity can still be maintained while fasting, but excessive activity that can increase the risk of hypoglycemia should be avoided. A walk or light jog after the sunset meal can be considered.

Glucose Monitoring

It’s important for patients to be able to identify when they’re either hypoglycemic or hyperglycemic in order to take the appropriate next steps. More frequent glucose monitoring throughout the month may be needed, and should the need arise for them to break their fast, they should do so immediately.

Glucose management in type 2 diabetics fasting during the month of Ramadan can be managed safely and effectively, but it requires patients to be aware of their limits and maintain good communication with their health care providers. In certain patients, specialized drug or dose tailoring will be needed for optimal control.

Recommended Reading

  • Al-Arouj M, Bouguerra R, Buse J, et al. Recommendations for management of diabetes during Ramadan. Diabetes Care. 2005;28(9):2305-2311.
  • Ali S, Davies MJ, Brady EM, et al. Guidelines for managing diabetes in Ramadan. Diabetic Medicine. 2016 Feb [Epub ahead of print].
  • Hassan CP, Khalid SA. The diabetic patient in Ramadan. Avicenna J Med. 2014;4(2):29-33.
  • Tucker ME. Diabetes management challenging during Ramadan. Medscape. Published July 9, 2013.

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