Which diabetes mellitus (DM) medication groups should be stopped or adjusted in a patient with type 2 diabetes during the fasting month?

Diabetes Medication Management During Fasting Month

Sulfonylureas should be stopped or significantly dose-reduced during fasting periods due to their inherent hypoglycemia risk, while metformin and glitazones can generally be continued with timing adjustments. 1

High-Risk Medications Requiring Discontinuation or Major Adjustment

Sulfonylureas (Highest Risk)

• Sulfonylureas carry inherent hypoglycemia risk during fasting and require individualized, cautious use with significant dose reduction or discontinuation 1
• For patients on once-daily sulfonylureas (e.g., glimepiride 4 mg, gliclazide MR 60 mg): shift the entire dose to before the sunset meal (Iftar) rather than morning 2, 3
• For patients on twice-daily sulfonylureas (e.g., glibenclamide 5 mg twice daily): use only half the usual morning dose at predawn (Suhur) and the full dose at sunset (Iftar) 2, 3
• The hypoglycemia risk is substantial enough that many clinicians prefer switching to safer alternatives before Ramadan begins 1

Insulin (Very High Risk)

• Patients with type 1 diabetes are at very high risk and should be strongly advised against fasting 1, 2
• For type 2 diabetes patients on insulin: similar risks exist though hypoglycemia incidence is lower, requiring significant dose reduction and multiple daily glucose checks 1
• For premixed insulin 70/30 twice daily (e.g., 30 units morning, 20 units evening): use the usual morning dose at sunset (Iftar) and only half the evening dose at predawn (Suhur) 2
• Excessive insulin reduction risks hyperglycemia and diabetic ketoacidosis, creating a narrow therapeutic window 2

Safe Medications Requiring Only Timing Adjustments

Metformin (Low Risk - Continue)

• Metformin alone may be safe for patients to fast because hypoglycemia risk is minimal 1
• Adjust dosing to two-thirds of total daily dose immediately before the sunset meal (Iftar), and one-third before the predawn meal (Suhur) 1
• For example: metformin 500 mg three times daily becomes 1,000 mg at Iftar and 500 mg at Suhur 2
• Extended-release formulations may improve tolerability during the fasting period 4

Thiazolidinediones/Glitazones (Low Risk - Continue)

• Patients on glitazones (pioglitazone or rosiglitazone) have low hypoglycemia risk and usually require no dose change 1
• Once-daily dosing can continue unchanged during fasting 2

Medications Safe Without Adjustment

Diet and Exercise Control Only

• No medication changes needed 2
• Modify timing and intensity of exercise to avoid hypoglycemia 2
• Ensure adequate fluid intake during non-fasting hours 2

Absolute Contraindications to Fasting

Patients with type 1 diabetes should be strongly advised to not fast due to very high risk of severe hypoglycemia, hypoglycemia unawareness, or diabetic ketoacidosis 2, 1

Additional high-risk groups who should avoid fasting include:

• Pregnant women with any form of diabetes (type 1, type 2, or gestational) face high morbidity and mortality risk to both fetus and mother 2
• Very elderly patients with type 2 diabetes requiring insulin for many years (suggesting β-cell failure) 2
• Patients with history of recurrent hypoglycemia or hypoglycemia unawareness 2

Critical Monitoring Requirements

• Close follow-up is essential during the first 3-4 weeks with frequent glucose checks if diabetic 1
• Patients must receive pre-Ramadan assessment and education on physical activity, meal planning, glucose monitoring, and medication timing 2
• Ensure adequate hydration during non-fasting periods, especially in patients on anticoagulation 1

Common Pitfalls to Avoid

• Never assume all oral diabetes medications have the same meal timing requirements - sulfonylureas behave very differently from metformin or glitazones 5
• Avoid taking metformin on an empty stomach as it increases gastrointestinal side effects 5
• Do not reduce insulin doses excessively in an attempt to prevent hypoglycemia, as this creates risk for hyperglycemia and ketoacidosis 2
• Patients should distribute calories over two to three smaller meals during the non-fasting interval to prevent postprandial hyperglycemia 1