Practical experience and challenges in nutritional management of glucose transporter 1 deficiency syndrome: Provider survey results.

Ketogenic diets (KDs) are recommended as precision therapy for glucose transporter 1 deficiency syndrome (GLUT-1 DS) but there are no recommendations for optimal implementation in this population. We administered an online survey targeting clinicians with experience implementing KDs in GLUT-1 DS, focusing on diet selection, initiation, and management. Respondents were primarily experienced registered dietitian nutritionists (RDNs) from 34 centers in 10 countries. Most reported a preference for carbohydrate counting or ratios under 3:1. KD-related laboratory monitoring (including blood ketones) and vitamin/mineral supplementation did not differ for GLUT-1 DS patients compared to the epilepsy population. Routine use of exogenous ketones was not endorsed for improved ketosis, whereas MCT oil is a commonly used supplement. Respondents overwhelmingly endorsed discussing and implementing gastrostomy feedings to support continued dietary therapy when medically indicated. Most but not all providers (80%) were familiar with the 2020 consensus guidelines. Our survey demonstrates practice variability among experienced dietitians, particularly in diet type and ratio. Identified challenges carry clinical significance, as the diet is a precision therapy in GLUT1-DS. Further research is needed to examine the outcomes of different approaches to KDs in GLUT-1 DS before consensus about the most effective interventions can be reached. PLAIN LANGUAGE SUMMARY: Glucose transporter deficiency syndrome is a genetic condition caused by an inability to move sugar (glucose) into the brain, which is needed for proper brain function. Ketogenic diets (low in carbohydrate and high in fat) are the established treatment to help control symptoms. Although the diet is effective, it can be challenging. To understand these challenges, we surveyed experts in ketogenic diet management and found significant variability regarding specifics of how the diet is managed. More research is needed before one approach can be endorsed as most effective.