Type 1 diabetes & fasting

There are times when people with diabetes consider fasting. This may be for cultural or religious reasons, such as when Muslims fast for Ramadan. Ramadan forbids the ingestion of any substance during daylight hours so it can be problematic for people with diabetes. Any alteration to your diet may affect the control of your diabetes, so you must consult your healthcare team before making any changes.

Ten years ago, Ramadan fell in midwinter meaning short days but because the fast follows the lunar calendar, in 2012 it falls in August and daylight can last up to 17 hours.

“Ramadan fasting is not compulsory – you are exempt if your health would be in danger,” says Dr Tahseen Chowdhury, a diabetes consultant at the Royal London and Barts Health NHS Trust in London. “Your healthcare team may advise against fasting if you have poor diabetes control or if there is evidence of complications.

“Also, those with Type 2 diabetes should avoid fasting if they have suffered severe hypoglycaemia (low blood sugar), such as that causing a loss of consciousness, within three months prior to Ramadan. And if you use insulin to control your Type 2 diabetes, the general advice is not to fast.”

All people with Type 1 diabetes are considered high risk and are advised not to fast.
“Fasting can affect your blood sugar levels,” explains Dr Chowdhury. “so, if you choose to fast, you must check your blood sugar levels more often – at least twice a day and immediately if you feel ill. There is a misconception that pricking your thumb to test your blood is breaking your fast, but religious authorities have assured us that this is not true.”

Long gaps between eating can cause hypoglycaemia (low blood sugar), so you must act if you have any symptoms such as confusion, dizziness, drowsiness, shaking, sweating or a fast heartbeat. “If your blood glucose levels are less than 4 mmol/l, you must break your fast and take some sugary fluids followed by starchy food immediately,” says Dr Chowdhury.

It is important to continue taking your medication, including injections, during any fast. If you take tablets to control your blood glucose, it may be possible to alter the time and/or dose during the fast but this will depend on the type of medication.
It may also be possible to adjust your medication but this needs careful monitoring from a healthcare professional. A reduction in the dosage of your medication can cause hyperglycaemia (high blood sugar), which can cause damage to nerves, blood vessels and other organs.

“Hyperglycaemia can lead to an increased risk of thrombosis and, rarely and in people with Type 1 diabetes, diabetic ketoacidosis (DKA), a serious complication where the body cannot use glucose as fuel because it doesn’t have enough insulin so it uses fat instead,” says Dr Chowdhury. “The symptoms of DKA include feeling very thirsty and urinating excessively – you must break the fast immediately if your blood glucose levels are higher than 17 mmol/l. If someone is fasting and does not drink enough, this will exacerbate dehydration and they may require urgent admission to hospital.”

If there is any damage to your eyes, kidneys, heart or the nerves in your hands and feet, it is not advisable to fast. “Kidney damage especially can be made worse by dehydration,” says Dr Chowdhury. Again, consult your healthcare team, who will know the extent of any existing damage.

When you do eat, eat healthily. You can enjoy special foods prepared during a religious fast, but you should consider quantities and choose healthy options, eg sugar-free drinks, fruit and vegetables, and foods that release sugar slowly such as wheat and beans. It’s also best to avoid foods high in saturated fat such as ghee, samosas and pakoras.

People whose diabetes is controlled by diet alone should be able to fast but this should be discussed with your healthcare team.
At the end of the fast, you should book a follow-up appointment with your healthcare team for a check-up and to monitor any adjustment back to your normal dosage of medication.