Ramadan fasting with insulin, sulfonylurea and reduced kidney function
Mr K is 58 years old, has had type 2 diabetes for 11 years, BMI 31 and an eGFR of 44 mL/min/1.73 m². His regimen is metformin 1,000 mg twice daily, glimepiride 4 mg with breakfast, and insulin glargine 24 units at 22:00. His HbA1c is 8.9%. He has had two hypoglycaemic episodes in the past three months (capillary glucose 3.1 and 2.8 mmol/L), one of them while driving. He is determined to fast the whole of Ramadan, which in Amman means roughly 15 hours without food or fluid, and refuses any plan that involves not fasting. He lives alone, drives a delivery van, and checks his glucose irregularly. He asks whether he can 'just skip the morning tablets' during Ramadan.
1. Stratify his fasting risk and explain what the risk category obliges you to do.
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He falls into the high-risk category, which means fasting is not recommended - but the conversation does not end there.
Using the IDF-DAR risk framework, the factors that put him at high risk are:
- Recurrent hypoglycaemia, including one episode at 2.8 mmol/L in the last three months, which is a severe episode by definition and predicts recurrence.
- Reduced kidney function (eGFR 44) - glimepiride is renally cleared and its active metabolites accumulate, prolonging hypoglycaemia.
- Multiple daily medications including basal insulin, which increases the risk of daytime hypoglycaemia during a 15-hour fast.
- Living alone, so a nocturnal or pre-dawn hypoglycaemic event may go unwitnessed and untreated.
- Driving a delivery van, so hypoglycaemia endangers him and the public.
- Irregular self-monitoring, which removes the main safety net.
What the category obliges you to do: the physician must explain that Islamic law permits exemption from fasting for illness and that fasting is not a test of faith, but the decision remains the patient's. If he still chooses to fast, you document informed refusal, arrange a pre-Ramadan education session with the diabetes educator and dietitian, agree a written monitoring plan and a sick-day plan, give him a hypoglycaemia kit with glucagon if available, and book a review in the first week of Ramadan. You do not simply say 'skip the morning tablets' - the regimen change needs to be individualised and prescribed.
2. Propose a medication adjustment plan for Ramadan, with the rationale for each change and the safety monitoring that goes with it.
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Frame this as a physician-led plan that you prepare and reinforce; all doses are proposals, not prescriptions, and must be confirmed with the treating doctor.
- Glimepiride 4 mg with breakfast → reduce to 2 mg at iftar (or stop and use an alternative). Sulfonylureas are the commonest cause of Ramadan hypoglycaemia, and this drug is renally cleared. Giving a smaller dose at the evening meal matches the one large meal and removes the daytime peak. An alternative would be a DPP-4 inhibitor, which carries low hypoglycaemia risk in renal impairment.
- Metformin 1,000 mg twice daily → 500 mg twice daily, taken with iftar and with suhoor. Metformin does not itself cause hypoglycaemia, but with eGFR 44 the dose should be reduced and renal function rechecked; it should be stopped during any acute illness with dehydration.
- Insulin glargine 24 units at 22:00 → reduce by about 20% to roughly 18–20 units, given at iftar. A long-acting basal insulin given at the evening meal covers the fasting period with a lower peak than a daytime dose. The exact reduction depends on his fasting glucose readings in the first three days.
- Do not add a rapid-acting insulin at suhoor unless the physician specifically prescribes it; it increases daytime hypoglycaemia risk during the long fast.
Monitoring plan: capillary glucose four times daily - pre-dawn (suhoor), midday, mid-afternoon and before iftar - plus any time he feels symptoms, and always before driving. Record in a diary and bring it to review. Repeat electrolytes and creatinine at two weeks.
3. Write the hypoglycaemia and fasting-break instructions you will give him, and explain how you will check he has understood them.
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Instructions, in plain language, with a written copy:
- Know your numbers. Check glucose before driving and at the four set times. If it is below 3.9 mmol/L or you feel shaky, sweaty or confused, treat first.
- Treat the low. Take 15–20 g of fast-acting carbohydrate - half a glass of juice, three teaspoons of sugar or honey dissolved in water, or glucose tablets - then recheck after 15 minutes and repeat if still low. Once you are above 4 mmol/L, eat a slow-release carbohydrate such as bread or a small meal.
- Break the fast if your glucose is below 3.9 mmol/L, above 16.7 mmol/L, or if you have symptoms of hypoglycaemia or of dehydration. This is permitted in Islam and is a safety instruction, not a failure.
- Do not drive if your glucose is below 5 mmol/L. Treat first, then wait 45 minutes and recheck before starting the van.
- Sick-day rules: if you have vomiting, diarrhoea, fever or cannot keep fluids down, stop metformin, contact the clinic the same day, and do not fast that day.
- Keep a hypo kit at home and in the van: glucose tablets or juice, and a card or bracelet saying you have diabetes.
Checking understanding: use teach-back - ask him to tell you what he will do at 14:00 if his glucose reads 3.2 mmol/L and he is at the wheel. Ask him to demonstrate where the glucose tablets are in the van and to state the three numbers that mean 'break the fast'. Involve a family member or a friend from the mosque if he agrees, because he lives alone. Book a phone review on day 3 and a clinic review at the end of week one.