Ramadan is the ninth month of the Islamic calendar, when Muslims fast during daylight hours. It is based on a lunar calendar; therefore, the duration of daily fast and the overall period of the month of Ramadan vary each year depending on the geographical location and season. Two main meals are usually consumed during Ramadan, before sunrise, known in Arabic as ‘Sohur’, and after sunset, known as ‘Iftar’. Changes in meal frequency, daily physical activities and sleeping patterns during Ramadan may influence the glycaemic and other biochemical parameters in patients with diabetes 1–3. Although the Koran exempts sick people from fasting, many Muslims with diabetes may not perceive themselves as sick and choose to fast, despite medical advice to the contrary.
Effects of fasting on lipid profile and weight
Even though people abstain from any oral intake from sunrise to sunset, they eat considerable amounts of sweet and fried foods traditionally prepared for Ramadan during non-fasting hours, especially at the Iftar meal. An increase in daily caloric intake during Ramadan has been shown in healthy subjects 1, 4. However, some studies reported a decrease in daily caloric and carbohydrate intake in patients with type 1 and type 2 diabetes 5, 6.
Weight and body mass index
Weight and body mass index did not change before and 15 days after Ramadan in 120 patients with type 2 diabetes well controlled on diet or oral hypoglycaemic medications after receiving dietary advice and adjustment of the timing of their medications 7. In women with type 2 diabetes and a high body mass index (34.63 ± 3.29 kg/m2), fasting during Ramadan resulted in significant weight loss (−3.12 kg; p < 0.01), a decrease in meal frequency (2.2 ± 0.3 versus 4.3 ± 0.4) as well as in energy intake (1488 ± 118 versus 1823 ± 262 kcal/day) 8.
It was postulated that physiological adaptations during the month of fasting lead to an increase in reliance on fat as a source of fuel during daytime fasting 9. In obese patients with type 2 diabetes, dietary fat consumption increased (35.84 versus 25.36%), especially the saturated fats (231 kcal/day or 43.25% of total fat 8). Total cholesterol intake, as well as total and low-density lipoprotein cholesterol concentrations, increased significantly in non-obese patients with type 2 (n = 57) (p < 0.03) 10 and in type 2 patients with hyperlipidaemia on diet, fibrates or statins 11.
Effects of fasting on cardiovascular endpoints
A large population-based study conducted in Qatar, where 95% of the adult population fast for Ramadan, has shown no significant difference in hospital admissions for acute coronary syndrome between Ramadan and non-fasting months (p < 0.05) 12. A 13-year review of a stroke database also showed no significant difference in the number of hospitalizations for stroke during the fasting month of Ramadan as compared to other months (p < 0.05) 13.
Effects of fasting on glycaemic control
Several studies have demonstrated no change in haemoglobin A1c14 or fructosamine levels 10, 15 during Ramadan. However, it is the variation in glycaemia leading to severe hypo- and hyperglycaemia that is the main issue for patients with diabetes fasting for prolonged periods during Ramadan. A large epidemiological study, the Epidemiology of Diabetes and Ramadan study, showed that daytime fasting during Ramadan increased the risk of severe hypoglycaemia by 4.7-fold (from 3 to 14 events/100 people/month) in type 1 diabetes and 7.5-fold (from 0.4 to 3 events/100 people/month) in type 2 diabetes. The incidence of severe hyperglycaemia in patients with type 2 diabetes also increased fivefold 16. In a multicentre observational study (n = 1374), symptomatic hypoglycaemia occurred in about 20% of diabetic patients on sulphonylurea with or without metformin who fast during Ramadan 17, whilst other studies have not shown a significant increase in the risk of hypoglycaemia during Ramadan in patients treated with oral diabetic medications or insulin 18, 19.
Management of diabetes during Ramadan
Blood glucose monitoring and the potential role of continuous glucose monitoring
Blood glucose monitoring does not constitute a break of fast 20. All patients who fast should be provided with the means to monitor their blood glucose 21.
Continuous glucose monitoring has been shown to improve overall mean glucose, reduce glycaemic excursions and reduce time spent in hyperglycaemia in non-fasting type 2 diabetes subjects 22. Although it has not been studied, continuous glucose monitoring may be a useful tool in studying the glycaemic variability during Ramadan in patients with a history of hypoglycaemia and in raising an alarm if there is rapid decrease in glucose or pending hypoglycaemia.
A pre-Ramadan assessment of patients who wish to fast during Ramadan is recommended to assess whether their health risk increases by doing so 23. Other opportunities for discussions about fasting during Ramadan can be at the time of diagnosis and at an annual diabetes review. Consensus guidelines have categorized patients according to their health risks 23, 24. Patients in the high-risk category should be advised not to fast while those in the low risk can be allowed to fast. Those in the medium category should discuss with healthcare professionals their management of Ramadan several months before Ramadan to reduce their risks.
Muslim religious leaders also play an important role in the education regarding religious fasting, especially for patients with diabetes who are keen to fast but overlook the risks involved, and also for patients who do not wish to fast but do so in order not to alienate themselves from the rest of the Muslim community 25. Both religious leaders and healthcare professionals are crucial in providing education and support for safer fasting during Ramadan.
In a systematic review of randomized controlled trials of the effectiveness of self-management training in people with type 2 diabetes, educational interventions that involved patient collaboration were more effective than didactic interventions in improving glycaemic control (<6 months), weight and lipid profiles 26.
Structured educational sessions specific to Ramadan have been shown to be effective. In an observational study, patients who fasted without attending a structured education session had a fourfold increase in hypoglycaemic events, whereas those who attended a Ramadan-focused education programme had a significant decrease in hypoglycaemic events 27. Patients, as well as their family, are encouraged to attend so that awareness of hypo- and hyperglycaemic symptoms, planning of meals, blood glucose monitoring, administration of medications, physical activity and management of acute complications such as when to break the fast, are provided to the family as a whole. It is also a good opportunity to encourage healthy living advice, such as smoking cessation. It has been shown that Ramadan fasting has a positive impact in that it helps Muslim adults to quit smoking 28.
Management of type 1 diabetes during Ramadan
Patients with poorly controlled type 1 diabetes should not fast during Ramadan. If patients choose to fast against medical advice, it is advantageous if they are on a basal bolus regime and are familiar with carbohydrate counting 24. A small study (n = 9) of patients with type 1 diabetes using insulin glargine and insulin lispro or aspart, divided in a 6:4 ratio of the total 24-h insulin dose, reported no episodes of severe hypoglycaemia or diabetic ketoacidosis requiring hospitalization, and the haemoglobin A1c remained stable at the end of Ramadan. As the insulin requirement decreased by 28% from baseline (p = 0.002), it has been suggested that insulin should be reduced by 70% of the pre-Ramadan doses during the fast 29.
Insulin lispro, as a short-acting component of the basal bolus regimen, has been found to have a lower 2-h post-prandial glucose level after the sunset meal (p = 0.026), with less hypoglycaemia (p < 0.01), as compared to regular human insulin when given with neutral protamine hagedorn insulin in an open-label crossover study (n = 64) 30.
Insulin pump therapy (using a Medtronic MiniMed 722 model) was observed in 49 type 1 patients who fasted during Ramadan. Seventeen patients had hypoglycaemia requiring breaking the fast but no severe hypoglycaemia was reported. Usual hyperglycaemia was reported in nine patients, with one patient needing hospital admission due to a disconnected pump. The authors concluded that fasting during Ramadan is feasible in patients with type 1 diabetes using an insulin pump, provided that adequate counselling and support are available 31.
Management of type 2 diabetes during Ramadan
Oral hypoglycaemic drugs
For patients taking once-daily oral hypoglycaemic drugs (OHDs), particularly sulphonylureas in the morning during non-fasting times, it has been recommended that the usual morning dose be moved to the evening 32. However, a large prospective observational study (n = 332) demonstrated that the hypoglycaemic rates and overall glycaemic control did not change when once-daily glimepiride taken with breakfast before Ramadan was switched to an evening dose taken at Iftar during Ramadan 32.
Once-daily pioglitazone 30 mg has been considered safe with no increase in hypoglycaemia during Ramadan in patients already taking other OHDs or pioglitazone alone 33.
For patients taking twice- or thrice-daily doses of OHDs, most Ramadan studies have suggested adjusting to two doses during Ramadan, one dose at Sohur and one at Iftar 24, 34, 35. As Iftar is usually the larger meal during Ramadan, expert consensus suggested that the OHD dose should be split such that two thirds of the dose is taken at Iftar and one third at Sohur (as the lunchtime dose during the daytime fast is not allowed). For instance, for a regimen of metformin 500 mg three times a day, the adjusted regimen during Ramadan would be 500 mg at Sohur and 1000 mg at Iftar.
For patients who are not well controlled on metformin alone and are planning to fast during Ramadan, there is evidence showing that combining a dipeptidyl peptidase-4 inhibitor, rather than a sulphonylurea, with metformin led to less incidence of hypoglycaemia and better glycaemic control 36.
Thiazolidenediones and incretin-based therapies, such as dipeptidyl peptidase-4 inhibitors (e.g. sitagliptin and saxagliptin) and glucagon-like peptide-1 analogues (e.g. exenatide), may not need dose adjustment during Ramadan. However, other agents, such as sulphonylureas, may need dose reductions when used as a combination treatment.
Long-acting insulin, such as glargine, should be given at Iftar to avoid potential hypoglycaemia during daytime fasting 19. A dose reduction of 20% has been suggested in type 2 diabetic patients with a pre-Ramadan haemoglobin A1c < 8% 18.
A randomized, open-labelled, crossover study comparing Humalog Mix 25 and Humulin M3 showed that the former offered better postprandial blood glucose control after Iftar and a lower incidence of hypoglycaemia 37. It has also been suggested that patients taking twice-daily insulin should reduce the Sohur dose by 30% if they are well controlled, and consider switching to a Mix 50 preparation if their postprandial glucose remains raised 38.
Even though fasting during Ramadan in women without diabetes and with uncomplicated pregnancies has been shown to result in no significant change in maternal ketonaemia or adverse effect on intrauterine development 39, pregnant women with diabetes have been strongly advised against fasting due to the potential maternal and foetal risks associated with poor glycaemic control in pregnancy 23, 24. Therefore, pregnant women with diabetes should be made aware that they are exempted from fasting and that fasting during pregnancy may be associated with risks to the mother and foetus.
Bariatric surgery is increasingly being performed for the correction of morbid obesity in patients with diabetes. As bariatric surgery limits the amount of food and fluid that can be consumed in one sitting, patients who underwent bariatric procedures who fast may encounter problems with dehydration, vomiting and poor nutritional intake as prolonged fasting can lead to the desire to consume larger amounts quickly upon breaking the fast. It has been advised that patients should avoid total fasts in the first 12–18 months after bariatric surgery when new dietary habits are being established 40.
We have summarized (Figure 1) the recommendations for people with diabetes who fast during the month of Ramadan. There is an overwhelming need for better-designed clinical trials, which could provide us with evidence-based information and guidance in the management of patients with diabetes who wish to fast during Ramadan. Currently, we advocate a thorough assessment of a patient's individual risk and modifying the treatment accordingly, so as to reduce the risk of hypoglycaemia or hyperglycaemia. One effective way of managing patients would be by offering group education classes to enable patients to be empowered to manage their condition themselves during Ramadan.