How should diabetes meds be managed while fasting?

Fasting for morning labs usually doesn’t require adjustments.

But other fasts vary. For example, patients may fast from sundown to sundown during Yom Kippur…from dawn to dusk during Ramadan…or 18 hours/day with some intermittent fasting diets.

Help individualize a plan based on meds…and fast duration.

Meds that rarely cause hypoglycemia include metformin…pioglitazone…gliptins (Januvia, etc)…and GLP-1 agonists (Victoza, etc). These can generally be continued for intermittent or religious fasts…but may need to be held before procedures.

Labelling says to hold most SGLT2 inhibitors (Jardiance, etc) before surgery…due to risk of ketoacidosis. But some experts may also hold them before procedures or religious fasts…or if dehydration may occur.

Consider this a downside of using SGLT2 inhibitors in patients who plan to do religious fasting…or an intermittent fasting diet.

Insulin or sulfonylureas are bigger culprits for hypoglycemia.

In general, advise holding mealtime insulin or sulfonylureas once the patient stops eating. But suggest holding sulfonylureas 24 to 36 hours before a longer fast (24 hours, etc).

For basal insulin, think of giving about half the usual dose if the patient’s well controlled…or at higher risk of hypoglycemia (elderly, kidney impairment, etc).

Otherwise, consider reducing the dose by about one-third.

Suggest reducing doses of NPH or a long-acting analog (Lantus, Levemir, etc) at the START of the fast. But suggest reducing Tresiba the day BEFORE the fast…since it lasts almost 2 days.

Recommend frequent blood glucose monitoring while fasting in patients on insulin or a sulfonylurea. Advise other patients to check if they have symptoms of hypoglycemia…feeling shaky, dizzy, sweaty, etc.

Suggest breaking the fast for glucose below 3.8 mmol/L…or if patients have symptoms with glucose below 4.4 mmol/L.