Several of the world's great religions recommend a period of fasting or abstinence from certain foods. Of these, the Islamic fast during the Muslim month of Ramadan is strictly observed every year. Islam specifically outlines one full month of intermittent fasting. The experience of fasting is intended to teach Muslims self-discipline and self-restraint and remind them of the plight of the impoverished. Muslims observing the fast are required to abstain not only from eating and drinking, but also from consuming oral medications and intravenous nutritional fluids.

The month of Ramadan contains 28 days to 30 days. The dates of observance differ each year because Ramadan is set to a lunar calendar. Fasting extends each day from dawn until sunset, a period which varies by geographical location and season. In summer months and northern latitudes, the fast can last up to 18 hours or more. Islam recommends that fasting Muslims eat a meal before dawn, called "sahur." Individuals are exempt from Ramadan fasting if they are suffering from an illness that could be adversely affected by fasting. They are allowed to restrain from fasting for one day to all 30 days, depending on the condition of their illness. People diagnosed with diabetes fall into this category and are exempt from the fasting requirement, but they are often loathe to accept this concession.  Physicians working in Muslims countries and communities commonly face the difficult task of advising diabetic patients whether it is safe to fast, as well as recommending the dietary and drug regimens diabetics should follow if they decide to fast. The lack of adequate literature on this subject makes it difficult to answer these questions. To judge correctly whether to grant medical permission to fast to a diabetic patient, it is essential physicians have an appreciation of the effect of Ramadan fasting on the pathophysiology of diabetes mellitus. In this article, we first review principles of carbohydrate metabolism and alterations of certain biochemical variables in diabetics observing Ramadan fasting. We then overview current medical recommendations that allow certain diabetic patients to fast and outline terms for diabetic patients, particularly IDDM patients, who should not fast but insist on fasting.

The effect of experimental short-term fasting on carbohydrate metabolism has been extensively studied ^(1,2). It has been uniformly found that a slight decrease in serum glucose to 3.3 mmol to 3.9 mmol (60 mg/dl to 70 mg/dl) occurs in normal adults a few hours after fasting has begun. However, the reduction in serum glucose ceases due to increased gluconeogenesis in the liver. That occurs because of a decrease in insulin concentration and a rise in glucagon and sympathetic activity ⁽³⁾.   In children aged one years to nine years, fasting for a 24-hour period has caused a decrease in the blood glucose to half of the baseline figure for normal children of that age group. In 22% of these children, blood glucose has fallen below 40 mg/dl ⁽⁴⁾. Few studies have shown the effect of Ramadan fasting on serum glucose ^(5-9). One study has shown a slight decrease in serum glucose in the first days of Ramadan, followed by normalization by the twentieth day and a slight rise by the twenty-ninth day of Ramadan ⁽⁶⁾. The lowest serum glucose level in this study was 63 mg/dl. Others have shown a mild increase ⁽⁷⁾ or variation in serum glucose concentration ^(8,9), but all of them fell within physiological limits ⁽⁶⁾. From the foregoing studies, one may assume that the stores of glycogen, along with some degree of gluconeogenesis, maintain normal limits of serum glucose when a fast follows a large pre-dawn meal. However, slight changes in serum glucose may occur in individuals depending upon food habits and individual differences in metabolism and energy regulation.

(a) In normal subjects:

Weight losses of 1.7 kg. ⁽¹⁰⁾, 1.8 kg. ⁽¹¹⁾, 2.0 kg. ⁽¹²⁾ and 3.8 kg ⁽¹³⁾ have been reported in normal weight individuals after they have fasted for the month of Ramadan. In one study that was over-represented by females, no change in body weight was seen ⁽¹⁴⁾. It has also been reported that overweight persons lose more weight than normal or underweight subjects ⁽¹²⁾.

(b) In diabetics:

A review of literature shows controversy about weight changes in diabetics during Ramadan. ^(6,15-24). In one group of studies, patients had an increase in their weight ^(17,21). In another group, there were no change ^{(15,19,22,23)} or a decrease ^{(6,16,18,20,24)} in body weight.  While no food or drink is consumed between dawn and sunset during the month of Ramadan, there is no restriction on the amount or type of food consumed at night ^(23,25). Furthermore, most diabetics reduce their daily activities ^(15,23) during this period in fear of hypoglycemia. These factors may result in not only a lack of weight loss, but also a weight gain in such patients ⁽²⁶⁾. (See later discussion about nutrition and physical activity.)

Most patients show no significant change in their glucose control ^(3,23,24,27). In some patients, serum glucose concentration may fall or rise ^(28-30). This variation may be due to the amount or type of food consumption, regularity of taking medications, engorging after the fast is broken, or decreased physical activities. In most cases, no episode of acute complications (hypoglycemic or hyperglycemic types) occurs in patients under medical management ^(9,15,16,22), And only a few cases of biochemical hypoglycemia without clinical hazards have been reported ^(17,19,25).

In general, HbAIC values show no change or even improvement during Ramadan ^{(15-18,20,22,23,25,27,28,32)}. Only two studies have reported slight increases in glycated hemoglobin levels ^(19,31). However, one report has emphasized the same increase in non-fasting patients as fasting patients ⁽³¹⁾, and the other has shown a return to initial levels immediately after the month of Ramadan ⁽¹⁹⁾.

The amount of fructosamine ^{(17,22,24,30,32)}, insulin, C-peptide ^(23,30) also has been reported to have no significant change before and during Ramadan fasting.

The amount of Energy (calorie) intake have been reported in some of the literature, indicating a decrease in energy intake ^(24,28).

Most patients with non-insulin dependent diabetes mellitus (NIDDM, diabetes type II) and insulin dependent diabetes mellitus (IDDM, diabetes type I) show no change or a slight decrease in concentrations of total cholesterol and triglyceride ^{(15-19,27,28,32)}. Increase in total cholesterol levels during Ramadan seldom occurs ⁽²³⁾. As in healthy persons ^(33-36), few studies have reported increases in high-density-lipoprotein (HDL) cholesterol in diabetics during Ramadan ^(18,19,27). One report indicates an increase in low-density-lipoprotein (LDL) cholesterol and a decrease in HDL-cholesterol ⁽²⁸⁾. Until there is a standardization of diabetes Ramadan research in three fundamental factors -- the Three D Triangle of drug regimens, diet control and daily activity -- the benefits or hazards of Ramadan fasting on diabetics serum lipids is unclear.

Serum creatinine, uric acid, blood urea nitrogen, protein, albumin, alanine amino-transferase, aspartate amino-transferase values do not show significant changes during the fasting period ^(15,17,32). Slight non-significant increases in some biological parameters may be due to dehydration and metabolic adaptation and have no clinical presentation.

FASTING GUIDELINES TO DIABETICS

During the last two decades, a better understanding of pathophysiological changes during Ramadan fasting in diabetic patients has provided a few guidelines on how to advise diabetics who want to fast. Physicians working with Muslim diabetics should employ certain criteria to advise their patients regarding the safety of Ramadan fasting.

The following criteria should be helpful in making such a decision ^(20,37):

Forbid fasting in:

• All brittle type I diabetic patients;

• Poorly controlled type I or type II diabetic patients;

• Diabetic patients known to be incompliant in terms of following advice on diet drug regimens and daily activity;

• Diabetic patients with serious complications such as unstable angina or uncontrolled hypertension;

• Patients with a history of diabetic ketoacidosis;

• Pregnant diabetic patients;

• Diabetic patients will inter-current infections;

• Elderly patients with any degree of alertness problems;

• Two or more episodes of hypoglycemia and/or hyperglycemia during Ramadan.

 Allow fasting in:

• Patients who do not have the aforementioned criteria;

• Patient who accept medical advisement.

 Encourage fasting in:

• All overweight NIDDM patients (except for pregnant or nursing mothers) whose diabetes is stable with weight levels 20% above the ideal weight or body mass index (body weight, kg/height, meters squared) greater than 28.

NIDDM patients and IDDM patients who insist on fasting should be given a few recommendations about fasting ⁽¹⁶⁾. They should be forbidden from skipping meals, taking medication irregularly or gorging after the fast is broken ⁽²⁶⁾.

The principles of pre-Ramadan considerations are ⁽³⁷⁾:

1. assessment of physical well being;

2. assessment of metabolic control;

3. adjustment of the diet protocol for Ramadan fasting;

4. adjustment of the drug regimen e.g. change long-acting hypoglycemic drugs to short-acting drugs to prevent hypoglycemia);

5. encouragement of continued proper physical activity;

6. recognition of warning symptoms of dehydration, hypoglycemia and other possible complications.

I. Nutrition and Ramadan fasting:

Dietary indiscretion during the non-fasting period with excessive gorging, or compensatory eating, of carbohydrate and fatty foods contributes to the tendency towards hyperglycemia and weight gain ^(21,23). It has been emphasized that Ramadan fasting benefits appear only in patients who maintain their appropriate diets ^(24,38,39). Thus, in order to optimize control, diabetics must be reminded to abstain from the high-calorie and highly-refined foods prepared during this month ⁽³⁸⁾.

II. Physical activity and Ramadan fasting:

Several studies indicate that light to moderate regular exercise during Ramadan fasting is harmless for NIDDM patients ⁽¹⁵⁾. It has been shown that fasting does not interfere with tolerance to exercise ⁽⁴⁰⁾. It should be impressed upon diabetic patients that it is necessary to continue their usual physical activity especially during non-fasting periods ⁽⁴¹⁾

III. Drug regimens for IDDM patients:

Some experienced physicians conclude Ramadan fasting is safe for IDDM patients with proper self-monitoring and close professional supervision ⁽¹⁶⁾. It is fundamental to adjust the insulin regimen for good IDDM control during Ramadan fasting. Two insulin therapy methods have been studied successfully:

1. Three-dose insulin regimen: two doses before meals (sunset and Dawn) of short-acting insulin and one dose in the late evening of intermediate-acting insulin ⁽¹⁶⁾.

2. Two-dose insulin regimen: Evening insulin combined with short-acting and medium-acting insulin equivalent to the previous morning dosage, and a pre-dawn insulin consisting only of a regular dosage of 0.1-0.2 unit/kg ⁽²⁵⁾.

Home blood glucose monitoring should be performed just before the sunset meal and three hours afterwards. It should also be performed before the pre-dawn meal to adjust the insulin dose and prevent any hypoglycemia and post-prandial hyperglycemia following over-eating.

 IV. Drug regimens for NIDDM patients:

Available reports indicate that there are no major problems encountered with NIDDM overweight patients who observe fasting in Ramadan ⁽³⁾. With proper changes in the dosage of hypoglycemic agents there will be low risk for hypoglycemia and hyperglycemia.

The authors of the largest series of patients treated with glibenclamide during Ramadan recommended that diabetics switch the morning dose (together with any mid-day dose) of this drug with the dosage taken at sunset ⁽³¹⁾.

V. Other health tips for reduction of complications:

1. Implementation of the 3D Triangle of Ramadan -- drug regimen adjustment, diet control and daily activity -- as the three pillars for more successful fasting during Ramadan.

2. Diabetic home management that consists of:

   - Monitoring home blood glucose especially for IDDM patients, as described above;

   - Checking urine for acetone (IDDM patients);

   - Measuring daily weights and informing physicians of weight reduction (dehydration, low food intake, polyuria) or weight increase (excessive calorie intake) above two kilograms;

   Recording daily diet intake (prevention of excessive and very low energy consumption).

3. Education about warning symptoms of dehydration, hypoglycemia and hyperglycemia.

4. Education about breaking fast as soon as any complication or new harmful condition occurs.

5. Immediate medical help for diabetics who need medical help quickly, rather than waiting for medial assistance the next day.

6. Further attention on fasting during the summer season and geographical areas with long fasting hours.

 VI. IDDM children and Ramadan fasting:

We do not encourage fasting for IDDM children. However, a few studies demonstrate that fasting is safe among diabetic adolescents. Of these studies, one study concludes that Ramadan fasting is feasible in older children and children who have had diabetes for a long time, and it concludes fasting does not alter short-term metabolic control. Nevertheless, fasting should only be encouraged in children with good glycemic control and regular blood glucose monitoring at home ⁽²⁵⁾.

After the month of Ramadan ends, the patients therapeutic regimen should be changed back to its previous schedule. Patients should also be required to get an overall education about the impact of fasting on their physiology ⁽³⁷⁾.

From a methodological point of view, few research papers on Ramadan fasting are relevant because of the absence of control periods before Ramadan and afterwards, the absence of measurements during each week of Ramadan, a lack of attention to dietary habits, food composition, food value, caloric control, weight changes and the importance of the schedule during circadian periods.

It is recommended that all these factors should be taken into consideration and that all intervening and confounding variables should be under control. It is clear that more work should be done on Ramadan fasting to evaluate physiological and pathological changes with proper research methods ⁽⁴²⁾.

Fasting during the entire month of Ramadan is reserved usually for healthy Muslims. However, many diabetic patients are allowed to fast periodically during Ramadan. The magnitude of periodic total fasting effect on blood glucose and hepatic glucagon depends on the number of fasting days ⁽⁴³⁾, and this should be considered in all Ramadan fasting research activities.