Abstracts

This abstract is a recipient of the Nurse and Advanced Practice Provider Travel Award

Rationale: Glucose transporter type 1 deficiency syndrome (GLUT1DS) is a genetic condition associated with pathogenic variants in the SLC2A1 gene and can lead to complex neurological symptoms including epilepsy. Ketogenic diet therapy is considered the standard treatment for GLUT1DS (Daci et al., 2018; Pong et al., 2012). Ketogenic diet therapy consists of a high fat, low carbohydrate, and moderate protein diet which is typically prescribed in a ratio of grams of fat to grams of carbohydrate plus protein. The ratio may be altered based on levels of ketosis, efficacy, and adverse effects experienced while on the diet. Adverse effects of the diet may alter quality of life and compliance, and may include gastrointestinal disturbance, elevated serum lipids, and metabolic acidosis and risk of adverse effects increases on higher ratios of ketogenic diet therapy (Wells et al., 2020). While much research exists to show the efficacy of ketogenic therapy for seizure control in GLUT1DS, there are limited studies to define an adequate BHB therapy range or show the efficacy of higher ratio versus lower ratio ketogenic diet therapies. This retrospective study aims to identify trends in treatment with ketogenic diet therapy initiation in patients with GLUT1DS to contribute to the literature and identify changes in practice to current initiation standards.

Methods: A retrospective chart review was performed to identify patients at a large urban pediatric institution who had been diagnosed with GLUT1DS over the past 15 years. Age of GLUT1DS diagnosis, age of ketogenic diet initiation, ketogenic diet ratios, beta-hydroxybutyrate levels (BHB), medications and seizure frequency were collected.

Results: There were a total of 12 patients identified as having GLUT1DS (4 males [33%], 8 females [67%.] The mean age at diagnosis was 3.9 years. Of the 12 patients identified, baseline seizure frequency was available for 10; 5 had rare seizures, 1 had a few seizures per month, and 4 had daily seizures. The mean age of ketogenic diet initiation at 4.5 years. One patient was excluded from the review as patient did not start the diet. One other was excluded for having started diet at an outside hospital. Of the remaining 10 patients, 9/10 (90%) were on medication at the time of diet initiation. One month follow up data was available for 6 of the patients, 5/6 (83%) were on a 3:1 ratio. Mean BHB was 3.5 at 1 month, 3.6 at 6 months and 3.5 at 1 year.  At 1 year 5/10 (50%) were off all ASMs, 3/10 (30%) were still on 1 ASM, 2/10 (20%) have not yet reached 1 year follow up.

Conclusions: A review of practice for patients with GLUT1 at our institution reflected that a 3:1 ratio of the diet was effective in a majority of patients maintained on ketogenic diet therapy, with the mean BHB across the first year of therapy being maintained between to 3.5-3.6 mmol/L. These preliminarily data suggest that lower ratios of ketogenic diet therapy may be acceptable in patients with GLUT1 and aid in mitigating side effects of long-term use. Larger studies are warranted to further evaluate and establish standardization of ketogenic diet therapy ratios in patients with GLUT1DS for seizure control and goal range of BHB levels.

Funding: Not applicable