Most doctors don't recommend fasting for diabetes patients. A study done in 13 Islamic countries on 12,243 diabetic people who fasted in Ramadan found they had a high rate of serious complications. On the other hand, few studies on small groups suggest no clear difference in complications. Below we discuss complications linked to fasting in diabetes patients.
First: low blood sugar levels
Lack of food is a known cause of low blood sugar. Although the effect of Ramadan fasting on low blood sugar isn't fully confirmed. the latest database in EPIDIAR study shows that Ramadan fasting causes a sharp drop in blood sugar levels, needing hospital admission. But this happened with patients who changed their doses of diabetes meds or insulin, and also with people who made big changes in their lifestyle.
Second: High blood sugar levels
Recent long-term studies on the effect of diabetes on disease and death show, for example: DCCT and UKPDS. There is a link between high blood sugar and complications in small blood vessels, and it might also be linked to problems in larger vessels. but there is no evidence linking short repeated yearly blood sugar spikes lasting about 4 weeks to diabetes complications.
1-5 people out of 100 with type 2 diabetes in the EPIDIAR study showed severe high blood sugar needing hospital stays during Ramadan fasting, while 5-17 out of 100 with type 1 diabetes had a strong rise in blood sugar with or without more ketones.
The high blood sugar might be caused by cutting medication doses too much to avoid low blood sugar. Patients who ate large amounts of food and/or sugar had clear big increases in blood sugar levels.
Third: Diabetic ketoacidosis
People with diabetes, especially type 1 patients fasting Ramadan, face a risk of diabetic ketoacidosis, especially if their blood sugar was high before Ramadan. The cause can be lowering insulin doses during Ramadan, assuming the person will eat less during the month.
Fourth: Dehydration and blood clots
Drinking less water while fasting, especially for long hours, can cause dehydration. It can be severe in hot, humid places and for people doing hard physical work or sweating a lot. Also, dehydration can cause osmotic urine output, volume loss, and electrolyte loss. It can lead to low blood pressure on standing or sitting up fast, especially in patients with autonomic nerve inflammation.
Dehydration also lowers blood pressure, so patients risk fainting, falls, injuries, and fractures. Plus, blood vessel tightening can raise the chance of clots forming.
Diabetics have a higher risk of clots because of more clotting factors, less clot blockers, and disrupted fibrin breakdown, plus thicker blood from dehydration that also raises clot risks. A study in Saudi Arabia showed more blockages in the eye veins of people fasting Ramadan but no increase in hospital admissions for heart artery or stroke problems in diabetic patients. There’s no data proving or disproving that fasting causes death in diabetics or healthy people.
