Fasting with Diabetes and GLP-1 Medications: What Your Pharmacist Wants You to Know

By Dr. Remi Olukoya, Pharm.D. | PharmaPlan Systems
Week 3 of Our Fasting Series | Reading Time: 10 minutes

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We are now in the third week of Lent and Ramadan, and if you have been following this series, you already know how to adjust your medication timing and which foods to eat (and avoid) when breaking your fast. This week, we are tackling the question I get asked most often in my pharmacy: "I have diabetes. Can I still fast safely?"

The short answer is: many people with diabetes can fast safely, but only with proper planning, the right medications, and close monitoring. The longer answer requires understanding your specific medications, your risk level, and the warning signs that mean you need to break your fast immediately.

This is especially important right now because millions of people worldwide are using newer diabetes and weight loss medications like Ozempic (semaglutide), Mounjaro (tirzepatide), and Wegovy while also observing religious fasts. If that describes you or someone you care about, this article was written for you.

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The Real Risk: Hypoglycemia During Fasting

When you fast, your body relies on stored glucose (glycogen) and eventually fat for energy. For most people, this process works smoothly. But if you have diabetes and take medications that lower blood sugar, fasting creates a dangerous equation: less food coming in + medication still pushing blood sugar down = potential hypoglycemia.

Hypoglycemia during fasting is not just uncomfortable. It can cause confusion, fainting, seizures, and in severe cases, it can be life-threatening. Research from the International Diabetes Federation (IDF) and Diabetes and Ramadan (DAR) Alliance shows that the risk of severe hypoglycemia increases significantly during Ramadan fasting, particularly in patients taking sulfonylureas or insulin [1].

The IDF-DAR Practical Guidelines (2021) now classify fasting patients with diabetes into three risk categories [2]:

If you are unsure where you fall, your pharmacist or doctor can help you assess your risk. The key point is this: your risk category determines which medications need adjustment and how closely you need to monitor.

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Your Diabetes Medications During Fasting: A Complete Breakdown

Not all diabetes medications carry the same risk during fasting. Here is what you need to know about each class:

Metformin: The Low-Risk Foundation

Metformin is the most commonly prescribed diabetes medication worldwide, and the good news is that it carries a very low risk of hypoglycemia when used alone. During fasting:

• If you take it once daily: Take it at Iftar (sunset meal) or your main meal when breaking your fast
• If you take it twice daily: Take one dose at Suhoor (pre-dawn meal) and one at Iftar
• Extended-release formulations: Take the full dose at Iftar

The main concern with metformin during fasting is gastrointestinal side effects, which can worsen on an empty stomach. Always take it with food.

Sulfonylureas: The High-Risk Medications

Medications like glipizide, glyburide (glibenclamide), and glimepiride are the most dangerous diabetes medications during fasting because they stimulate your pancreas to release insulin regardless of whether you have eaten. This is the primary cause of fasting-related hypoglycemia in people with diabetes.

If you take a sulfonylurea and choose to fast:

• Glyburide/Glibenclamide: The IDF-DAR guidelines specifically recommend switching to a safer alternative before Ramadan. This medication has the highest hypoglycemia risk [2]
• Glimepiride: The morning dose should be taken at Iftar, and the dose may need to be reduced by 50%
• Glipizide: Similar adjustments as glimepiride; take at Iftar with possible dose reduction

Critical warning: If you experience any symptoms of low blood sugar (shakiness, sweating, confusion, rapid heartbeat, blurred vision), you must break your fast immediately with a fast-acting sugar source. Your health takes priority, and all major Islamic scholars and Christian theologians agree that medical necessity is a valid reason to break a fast.

GLP-1 Receptor Agonists: The Fasting-Friendly Option

This is where the conversation gets exciting, because GLP-1 receptor agonists represent a genuine breakthrough for people who want to fast safely with diabetes. Medications in this class include:

• Semaglutide (Ozempic for diabetes, Wegovy for weight management)
• Liraglutide (Victoza for diabetes, Saxenda for weight management)
• Dulaglutide (Trulicity)
• Tirzepatide (Mounjaro, Zepbound)

A 2025 systematic review and meta-analysis published in the World Journal of Methodology analyzed all available studies on GLP-1 receptor agonists during Ramadan fasting and found remarkable results [3]:

• Patients on GLP-1 agonists had a 62% lower risk of documented symptomatic hypoglycemia compared to those on other diabetes medications (RR = 0.38, P = 0.02)
• Zero patients experienced severe hypoglycemia during fasting in any of the studies
• GLP-1 agonists provided modest additional benefits in blood sugar control (HbA1c) and weight loss during the fasting period

The reason GLP-1 agonists are so well-suited for fasting is their mechanism of action: they only stimulate insulin release when blood sugar is elevated. When your blood sugar is normal or low (as it might be during fasting), these medications essentially "turn off," dramatically reducing the risk of dangerous drops.

Practical tips for GLP-1 medications during fasting:

• Weekly injectables (Ozempic, Trulicity, Mounjaro, Wegovy): These do NOT break your fast because they are injected, not taken orally. Continue on your regular weekly schedule. Most Islamic scholars confirm that injections that are not nutritive do not invalidate the fast [4]
• Oral semaglutide (Rybelsus): This must be taken on an empty stomach with water. During Ramadan, take it at least 30 minutes before Suhoor. The Pharmacy Times recommends maintaining the dose at 7mg during fasting periods [5]
• Daily injectables (Victoza, Saxenda): Take at Iftar or Suhoor, whichever is more convenient

Important GI warning: The meta-analysis found that GLP-1 agonists do increase the risk of nausea (14 times higher) and vomiting (6 times higher) compared to other medications during fasting [3]. If you are newly starting a GLP-1 agonist, it is best to begin and stabilize on the medication before the fasting period starts, not during it. Starting during fasting can make the GI side effects significantly worse.

SGLT2 Inhibitors: The Dehydration Risk

Medications like empagliflozin (Jardiance), dapagliflozin (Farxiga), and canagliflozin (Invokana) work by making your kidneys excrete excess glucose through urine. During fasting, when you are already not drinking water for extended periods, this creates a real risk of dehydration and volume depletion.

Recommendations during fasting:

• Stay well-hydrated during non-fasting hours (drink at least 8-10 glasses of water between Iftar and Suhoor)
• Monitor for signs of dehydration: dizziness, dark urine, excessive thirst, dry mouth
• Your doctor may recommend temporarily reducing the dose or switching to an alternative
• These medications have a low hypoglycemia risk when used alone, but dehydration is the primary concern

Insulin: Requires Careful Adjustment

If you take insulin and choose to fast, you must work with your healthcare provider to create a personalized adjustment plan. General principles include:

• Basal insulin (Lantus, Levemir, Tresiba): Usually reduced by 15-30% during fasting. Take at Iftar
• Rapid-acting insulin (Humalog, NovoLog): Skip the lunch dose entirely. Adjust breakfast dose to Suhoor and dinner dose to Iftar
• Pre-mixed insulin: Often needs to be switched to a basal-bolus regimen for safer fasting
• Continuous glucose monitors (CGMs): Highly recommended during fasting for real-time monitoring

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Blood Sugar Monitoring: Your Non-Negotiable Safety Net

Regardless of which medication you take, blood sugar monitoring during fasting is essential. The IDF-DAR guidelines recommend checking blood glucose [2]:

1. Before Suhoor (pre-dawn meal)
2. Mid-morning (around 10-11 AM during the fast)
3. Mid-afternoon (around 3-4 PM, the highest risk period for hypoglycemia)
4. Before Iftar (before breaking the fast at sunset)
5. 2 hours after Iftar (to check for post-meal spikes)
6. Any time you feel unwell

Important: Checking your blood sugar with a finger-stick glucose meter or wearing a continuous glucose monitor (CGM) does NOT break your fast according to the majority of Islamic scholars, as it does not involve ingesting anything [6].

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When to Break Your Fast Immediately

No matter how committed you are to your fast, there are situations where continuing to fast becomes medically dangerous. Break your fast immediately if:

• Blood sugar drops below 70 mg/dL (3.9 mmol/L) at any point
• Blood sugar rises above 300 mg/dL (16.7 mmol/L)
• You experience symptoms of hypoglycemia: trembling, sweating, confusion, rapid heartbeat, blurred vision
• You experience symptoms of hyperglycemia: excessive thirst, frequent urination, nausea, fruity breath odor
• You feel faint, dizzy, or disoriented
• You develop signs of dehydration that do not resolve

Remember: both Islamic and Christian traditions provide clear exemptions for people whose health would be endangered by fasting. In Islam, those who are ill are explicitly exempted from fasting and can make up the days later or provide Fidyah (feeding a person in need for each day missed). In Christianity, fasting is never intended to harm your health, and pastoral guidance supports medical exemptions.

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The Pre-Fasting Consultation: What to Ask Your Pharmacist

If you have diabetes and plan to fast, schedule a consultation with your pharmacist or doctor at least 4-6 weeks before the fasting period begins. Here is your checklist:

1. Risk assessment: "What is my risk category for fasting with my current diabetes control?"
2. Medication adjustment: "Do any of my medications need to be changed, reduced, or switched before I start fasting?"
3. GLP-1 discussion: "Would switching to a GLP-1 agonist like Ozempic or Mounjaro be safer for me during fasting?" (This is especially relevant if you are currently on a sulfonylurea)
4. Monitoring plan: "How often should I check my blood sugar, and what numbers should concern me?"
5. Emergency plan: "What should I do if my blood sugar goes too low or too high during the fast?"
6. Hydration strategy: "How much water should I drink during non-fasting hours, especially if I take an SGLT2 inhibitor?"

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A Note on GLP-1 Medications for Weight Management During Fasting

Many people who are not diabetic are now taking GLP-1 medications like Wegovy or Zepbound for weight management. If this applies to you and you are fasting:

• These medications are generally safe to continue during fasting
• The appetite-suppressing effect may actually make fasting easier
• However, the reduced appetite combined with fasting can lead to inadequate nutrition if you are not careful
• Make sure your Iftar and Suhoor meals are nutrient-dense and provide adequate protein, healthy fats, and complex carbohydrates
• Do not skip Suhoor just because you do not feel hungry. Your body needs fuel for the fasting hours ahead
• Stay alert for excessive nausea or vomiting, which may worsen during fasting periods

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Next Week: Ending the Fast Safely

As we approach the final week of Ramadan and continue through Lent, next week's article will cover the critical transition period: how to safely end your fast, readjust your medications, and avoid the common health pitfalls of the post-fasting period. The Eid celebration and Easter feasting can create their own medication challenges, and we will make sure you are prepared.

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Download Your Free Resources

📥 Medication Fasting Safety Checklist - Print it, fill it out, and bring it to your pharmacist appointment!

📚 Foods That Clash With Your Prescriptions - My comprehensive eBook with detailed food-drug interaction guides ($9.99, includes 2 FREE bonus guides)

🤖 MediMeal Safe Assistant - AI-powered chatbot that checks your specific medications against foods in real-time (subscription required)

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References

[1] Salti I, Benard E, Detournay B, et al. A population-based study of diabetes and its characteristics during the fasting month of Ramadan in 13 countries. Diabetes Care. 2004;27(10):2306-2311. doi:10.2337/diacare.27.10.2306

[2] International Diabetes Federation and Diabetes and Ramadan International Alliance. IDF-DAR Practical Guidelines for Management of Diabetes During Ramadan. 2021. Available at: https://idf.org/media/uploads/2024/07/IDF_DaR_Practical_Guidelines_Ramadan.pdf

[3] Kamrul-Hasan ABM, Pappachan JM, Ashraf H, et al. Safety and efficacy of glucagon-like peptide-1 receptor agonists in individuals with type 2 diabetes mellitus fasting during Ramadan: a systematic review and meta-analysis. World J Methodol. 2025;15(4):105478. doi:10.5662/wjm.v15.i4.105478

[4] Ahmed M, Magdi M, Adeleke Y, et al. Safety and effectiveness of newer antidiabetic medications during Ramadan fasting. J Diabetes Metab Disord. 2022;21(2):1823-1833. doi:10.1007/s40200-022-01145-6

[5] Pharmacy Times. Iftaar and Insulin: Managing Diabetes During Ramadan. 2025. Available at: https://www.pharmacytimes.com/view/iftaar-and-insulin-managing-diabetes-during-ramadan

[6] Al-Arouj M, Assaad-Khalil S, Buse J, et al. Recommendations for management of diabetes during Ramadan: update 2010. Diabetes Care. 2010;33(8):1895-1902. doi:10.2337/dc10-0896

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About the Author

Dr. Remi Olukoya is a licensed pharmacist (Pharm.D.) and founder of PharmaPlan Systems. With years of experience counseling patients on medication safety during religious fasting periods, she is passionate about making evidence-based pharmaceutical knowledge accessible to everyone. Her mission is to empower patients and healthcare professionals with the tools and information needed to navigate food-drug interactions safely.

Connect with PharmaPlan Systems:

• Website: pharmaplansystems.com
• Email: [email protected]
• Follow us on social media for daily medication safety tips

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Disclaimer: This blog post is for educational purposes only and does not constitute medical advice. Always consult with your healthcare provider or pharmacist before making changes to your medication regimen or fasting practices. Individual circumstances vary, and professional guidance is essential for safe medication management during fasting.