Short answer: It is a question to settle with your prescriber first. The Jardiance and Farxiga labels name a ketogenic diet, and eating fewer calories, among the triggers for ketoacidosis on SGLT2 medicines. This acid buildup can be life-threatening and can happen even when blood sugar is below 250 mg/dL. The labels do not ban the diet, but they say to watch for symptoms and consider checking ketones.
Section 5.1 of both the Jardiance and Farxiga labels covers ketoacidosis. It lists the conditions that can set it off: lower or missed insulin doses, an acute illness with fever, reduced calorie intake, a ketogenic diet, surgery, fluid loss and alcohol abuse. Type 1 diabetes and pancreas problems also raise the risk, and fatal cases have been reported in type 2 diabetes.
The Jardiance Medication Guide says ketoacidosis can happen in people who are sick, cannot eat or drink as usual, skip meals, are on a diet high in fat and low in carbohydrates (ketogenic diet), take less insulin than usual, drink too much alcohol, lose too much fluid, or have surgery.
Neither label sets a carbohydrate number or says a ketogenic diet is off limits. They ask prescribers to educate patients on the symptoms and to consider ketone checks in people at risk.
A ketogenic diet is designed to make the body burn fat and produce ketones. SGLT2 medicines also push the body toward making ketones, and the labels say the resulting ketoacidosis may come with blood sugar lower than expected, for example under 250 mg/dL. That means a normal glucose meter reading does not rule it out.
The labels also say urine sugar loss lasts about 3 days after stopping, and that there have been reports of ketoacidosis or urine sugar lasting more than 6 days and some up to 2 weeks after stopping an SGLT2 medicine.
The Medication Guide says to stop the medicine and call your healthcare provider or get medical help right away if these appear, and to check for ketones if possible, even if blood sugar is under 250 mg/dL.
Dehydration is a related warning. The Medication Guide says Jardiance can cause dehydration, with dizziness or weakness on standing, and higher risk in people on water pills or a low-salt diet, with kidney problems, or aged 65 and over.
Useful questions for the prescriber: whether the planned diet is safe with your medicine, whether to keep urine or blood ketone strips at home, what reading should prompt a call, and what to do on a day when you are sick or not eating. The labels also say to hold the medicine, if possible, in short-term situations that raise the risk; see SGLT2 medicines before surgery.
If you start a new diet, logging the start date, your doses and any symptoms in one place helps the prescriber see what changed. Dose Track keeps doses and notes together.
Read more on Dose Track: What is diabetic ketoacidosis? · Jardiance side effects · Farxiga side effects · Missed a Jardiance dose · Jardiance vs Farxiga