A certain family of diabetes medications may be to blame for causing a complication of type-2 diabetes that is usually associated only with type-1.

The diabetes medications at issue are known as sodium-glucose cotransporter-2 inhibitors, or SGLT2 inhibitors. These medications work by blocking the action of certain proteins that allow the blood to reabsorb glucose. With those proteins blocked, the excess glucose is removed from the blood and excreted in urine.

The class of SGLT2 inhibitors includes the relatively new diabetes medications Invokana (canagliflozin), Farxiga (dapagliflozin) and Jardiance (empagliflozin). Two other medications, Invokamet and Xigudo XR, contain the active ingredients in Invokana and Farxiga in combination with the older diabetes medication metformin.

All of these medications have been approved by the FDA to lower blood sugar in patients with type-2 diabetes. They have not been approved as treatments for type-1 diabetes, however.

In May the FDA issued a Drug Safety Communication warning of the possibility of developing ketoacidosis while taking any of these diabetes medications. The agency based this warning on a review of cases in its Adverse Event Reporting System (FAERS).

In cases reported from March 2013 to June 2014, the agency found 20 instances of acidosis reported as either diabetic ketoacidosis, ketoacidosis, or ketosis in patients who had been taking SGLT2 inhibitors. They say the FAERS system has continued to receive similar reports since June 2014.

Ketoacidosis can develop in diabetic patients when a lack of insulin prevents cells from being able to use the glucose that is in the blood. For lack of access to glucose, the cells begin metabolizing fat instead.

But fat metabolism can produce an excess of waste materials known as ketones, which can increase the acidity of the blood. Untreated ketoacidosis may lead to coma or death.

The FDA recommends that patients taking SGLT2 inhibitors be vigilant for possible symptoms of ketoacidosis. These include nausea, vomiting, abdominal pain, sleepiness, confusion, unusual fatigue, or difficulty breathing.

The agency advises physicians to discontinue their patients’ SGLT2 inhibitor treatment if acidosis is confirmed. Patients themselves are specifically advised not to change their diabetes medication regimen without first consulting their physician.

The FDA’s communication says the agency is continuing to monitor the situation and will determine whether to change its approved prescribing information for SGLT2 inhibitors.

The FDA says that ketoacidosis specific to diabetes usually develops as a result of low insulin levels or prolonged fasting, and it is usually accompanied by elevated blood sugar levels.

The FDA noted that the FAERS cases of ketoacidosis were atypical because the patients involved had type-2 diabetes, and at the time of their ketoacidosis their blood sugar levels were only slightly elevated.

Other possible side effects associated with SLGT2 inhibitors include dehydration, yeast infections, urinary tract infections, kidney trouble, and low blood sugar, potentially developing into clinical hypoglycemia. Clinical trials of canagliflozin also yielded reports of elevated levels of cholesterol.