GLUT1 Deficiency and Type 1 Diabetes: Case Study

Hello and welcome to Science with Sandra!

For this edition, I would like to highlight a recent publication titled “Treatment of an Opposing Metabolic Situation: GLUT1 Deficiency Syndrome and Type 1 Diabetes” by Dr. Anna Schoenlaub from the Department of Pediatrics at the Medical University of Innsbruck in Austria.

Dr. Schoenlaub and her team published a case report describing a 15-year-old girl with GLUT1 Deficiency who had been successfully treated for years with the ketogenic diet, specifically the Modified Atkins Diet (MAD). The diet helped keep her seizures under control and improved both her gait and cognitive development.

At age 15, she unexpectedly developed Type 1 Diabetes (T1D) and was admitted to the hospital with diabetic ketoacidosis (DKA), a dangerous condition caused by a lack of insulin that forces the body to break down fats for fuel, leading to a buildup of acidic ketones in the blood.

Treating both conditions, GLUT1 Deficiency and T1D, is very challenging because:

• GLUT1 Deficiency requires ketones to fuel the brain.
• T1D treatment usually aims to suppress ketosis using insulin.
• Too little insulin increases the risk of DKA.
• Too much insulin lowers ketones and may trigger seizures or movement symptoms.

Dr. Schoenlaub worked with a team of pediatric diabetologists, metabolic disease specialists, and pediatric neurologists to develop a balanced care plan. This included immediate and appropriate treatment of DKA, starting the patient on an insulin pump while keeping her on the MAD diet, and setting target ranges for both blood glucose and ketones:

• Blood glucose: 100–150 mg/dL to prevent hypoglycemia
• Ketones (β-Hydroxybutyrate): 1.5–2.5 mmol/L to avoid seizures and movement disorders
• HbA1c: <7.0% (53 mmol/mol)

Over two years of follow-up, the patient had no further episodes of DKA, maintained stable blood sugar levels, and her β-Hydroxybutyrate ranged between 0.4 and 2.2 mmol/L. Importantly, she did not experience any seizures or paroxysmal movement disorders during this period.

This case demonstrates that it is possible to safely manage both GLUT1 Deficiency and Type 1 Diabetes with careful monitoring and individualized planning.

Families should be aware that ketones are typically elevated in individuals on the ketogenic diet, but very high ketones combined with high blood glucose can indicate dangerous DKA.

If a case like this arises, it is essential for the child to be cared for by a specialized medical team, including a pediatric neurologist experienced in GLUT1 Deficiency, a metabolic disease specialist, a pediatric endocrinologist, and a dietitian familiar with ketogenic dietary therapies. This ensures proper insulin dosing, safe maintenance of therapeutic ketosis, and an emergency plan during illness.

Finally, Dr. Schoenlaub and her team also reviewed the literature on cases where individuals on ketogenic diet therapy later developed T1D, as well as cases where T1D patients were later started on ketogenic therapies for refractory epilepsy. According to the authors, there are no comprehensive guidelines for managing either scenario. They conclude that “a combination of T1D and GLUT1 Deficiency is a balancing act, but our case report may be helpful for these patients, showing that combining both therapies is possible.”

We thank Dr. Schoenlaub and her team for publishing this important work and for their dedication to caring for patients in our community!