Treatment of an Opposing Metabolic Situation: GLUT1-Deficiency Syndrome and Type 1 Diabetes.

Glucose transporter type 1 deficiency syndrome (GLUT1-DS) is a rare inborn disorder of metabolism leading to encephalopathy due to disturbed glucose transport via the blood-brain-barrier and consecutive energy deficit of the brain. Since ketone bodies can serve as an alternative fuel for the brain, ketogenic diet therapies (KDT) are the treatment of choice for these patients. KDT refers to all forms of nutrition that lead to the formation of ketone bodies. We describe a 15-year-old girl with GLUT1-DS who was effectively treated with a form of KDT, a modified Atkins diet (MAD), and developed type 1 diabetes. After correction of the initial diabetic ketoacidosis (DKA), insulin pump treatment was started while staying on MAD. With this treatment regimen, no further DKA episodes occurred within 2 years of follow-up, current HbA1c 6.9%. Treatment of GLUT1-DS by KDT and type 1 diabetes (T1D) by insulin at the same time is challenging but feasible. The initial manifestation phase of T1D is critical and is made even more difficult by an already performed KDT. Target ranges for blood glucose AND β-hydroxybutyrate levels must be defined to optimize the insulin dosage. Additionally, patients, families, and caregivers need to be aware of the risk of this particular metabolic situation.