Given the epidemiology of diabetes in the UK, a significant number of Muslim patients will be preparing to fast during Ramadan, a lunar-based month with a duration varying between 29 and 30 days. Its timing changes with respect to seasons and in 2016 will require fasting for up to 18-20 hours. If fasting might lead to harmful consequences for the individual, it does not need to be done and patients with diabetes fall under this category because their chronic metabolic disorder may place them at high risk for various complications if the pattern and amount of their meal and fluid intake is markedly altered. The major complications of fasting include hypoglycaemia for which the EPIDIAR study showed a 4.7 and 7.5-fold increase in T1 and T2 diabetes respectively. The study also showed that the size of meals at the start and end of the fast resulted in a significant increase in admissions due to hyperglycaemia. Other potential complications include dehydration and ketoacidosis. Despite these risks, many patients still wish to fast. Increasing numbers of guidelines are available, all of which put patient safety at their centre including education, especially around the risk of hypoglycaemia which should result in ending the fast. For Type 1 diabetes, this is a particular risk if a pre-mixed insulin is used (especially when fasting during the summer months). Basal analogues are associated with lower episodes of hypoglycaemia with results of a study using insulin glargine in 15 relatively well-controlled patients with type 1 diabetes who fasted for 18 h showing that the mean plasma glucose declined from 6.95 to 5.2mmol/l during the fast. Short acting analogues may reduce the risk of post prandial hyperglycaemia, avoiding hypoglycaemia whilst pump therapy has clear benefits.  In T2DM, the increasing number of oral and injectable therapies provide flexibility. Clearly patients on diet, Metformin, gliptins or a glitazone are not at risk of hypoglycaemia. However, sulphonylureas, especially those with a longer half life can be problematic although one study in patients with type 2 diabetes who fasted showed that use of repaglinide was associated with less hypoglycaemia compared with glibenclamide. Newer agents such as SGLT2 inhibitors, whilst not causing hypoglycaemia clearly exacerbate the risk of dehydration.  In the recently published LIRA-Ramadan study, patients treated with Liraglutide during Ramadan were more likely to achieve an HbA1c <7% with no confirmed hypoglycaemia compared with a sulphonylurea. They also had significantly greater weight loss. In summary, a patient’s decision to fast should be made after discussion and education concerning the risks involved. The management plan must be individualised with the development of new agents increasing allows this.

Dr Mark Freeman