by Elijah Mohammed Andy Davies
Question from Elijah:
I am diabetic and presently taking Metformin and Glicazaride, but also doing lots of intermittent fasting every day of the week.
Elijah, please be careful. The medicine you call “Glicazaride” may be gliclazide, a sulfonylurea diabetes medicine. Gliclazide can cause low blood sugar, especially if meals are skipped, delayed, or reduced during fasting.
Metformin alone usually has a lower risk of low blood sugar, but the combination of fasting plus gliclazide can be risky without medical supervision.
Do not change or stop your diabetes medicines by yourself. Before continuing daily intermittent fasting, ask your doctor to review your glucose readings, kidney function, meal schedule, and medication timing.
Answer by Dr. Albana Greca, MD, MMedSc
Dear Elijah,
Intermittent fasting may help some people with type 2 diabetes reduce calorie intake, lose weight, and improve insulin sensitivity. But it is not automatically safe for every person with diabetes, especially when medicines that can cause low blood sugar are used.
Gliclazide helps the pancreas release more insulin. This can lower blood sugar even when you are not eating enough. If you fast every day while taking gliclazide, your risk of hypoglycemia may increase.
Low blood sugar can cause sweating, shaking, hunger, dizziness, fast heartbeat, headache, confusion, weakness, blurred vision, or fainting. Severe hypoglycemia can be dangerous.
If you often skip meals, it is important to compare your readings with our guide to common causes of low blood glucose, because medication and meal timing are frequent triggers.
Metformin works mainly by reducing excess glucose production by the liver and improving how the body uses insulin. By itself, metformin is less likely to cause low blood sugar than gliclazide.
However, fasting while taking several diabetes medicines still requires planning. Dehydration, kidney problems, alcohol, illness, very low calorie intake, or heavy exercise can make fasting less safe.
Patients who take more than one diabetes medicine may also find it useful to review our overview of diabetes medications, benefits, and side effects.
Daily intermittent fasting while using gliclazide should be discussed with your doctor. Your doctor may need to review the dose, timing, type of medicine, glucose targets, and whether fasting is appropriate for you.
This is especially important if you drive, do physical labor, live alone, have kidney disease, have a history of severe lows, do not feel low blood sugar symptoms, are elderly, are pregnant, or are fasting during illness.
For at least one week, keep a careful record of fasting glucose, pre-meal glucose, readings during the fasting window, symptoms, medicine times, meal times, exercise, and any low blood sugar treatment. A simple blood sugar log sheet can make this easier to show your doctor.
Ask your doctor what numbers are too low for you, when to break the fast, and whether you need a different medication schedule on fasting days.
Break the fast immediately if you have symptoms of low blood sugar or if your glucose is below your doctor’s safety limit. Many diabetes plans treat blood sugar below 70 mg/dL, or 3.9 mmol/L, as low.
Use fast-acting carbohydrate, such as glucose tablets, regular soda, fruit juice, or another treatment your doctor has recommended. Do not try to “push through” a low blood sugar episode to continue fasting.
If you are not sure how to interpret your readings during fasting, compare them with our guide on when blood sugar is too high or too low.
When you eat after fasting, avoid a large high-carbohydrate meal, because it can cause a glucose spike. A better meal includes non-starchy vegetables, protein, a measured portion of high-fiber carbohydrate, and a small amount of healthy fat.
Examples include vegetables with eggs, fish, chicken, beans, lentils, plain yogurt, oats, or a controlled portion of whole grains. Our guide to diabetes, carbs, and glycemic index can help you choose carbohydrates that raise glucose more slowly.
Do not fast if you are having repeated low blood sugar, severe highs, vomiting, dehydration, infection, ketones, confusion, or severe weakness. Seek urgent help for fainting, seizure, confusion, chest pain, trouble breathing, severe dehydration, or blood sugar that remains dangerously high or low.
Elijah, intermittent fasting may be possible for some people with type 2 diabetes, but gliclazide makes safety more complicated. Please do not continue daily fasting without a clear plan from your doctor for medicine timing, glucose monitoring, and when to break the fast.
Educational safety note: This answer is for general diabetes education only. It does not replace personal medical advice, diagnosis, or treatment. Do not start, stop, or change metformin, gliclazide, insulin, supplements, fasting schedules, diet, or exercise without speaking with your healthcare provider.
Last reviewed: July 2026.
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