GABA falls short for type 1 diabetes prevention in children

BARCELONA – Gamma aminobutyric acid (GABA) alone or given in combination with glutamic acid decarboxylase (GAD) had little to no effect on the progression of type 1 diabetes in children, according to early data presented at the annual meeting of the European Association for the Study of Diabetes.

There was no difference between the two active treatment groups and placebo for the primary outcome measure, which was the effect on meal-stimulated C-peptide secretion before and after 1 year of treatment, study investigator Kenneth L. McCormick, MD, reported, nor was there any difference in glycemic control, based on hemoglobin A_1c (HbA_1c) and insulin dose, between the children who received GABA alone (n = 39) or combined with GAD (n = 22), and those who received placebo (n = 30).

“However, the GABA–GAD combination tended to have greater efficacy [than placebo] in terms of the daily insulin dose and the fasting C-peptide–to–glucagon ratio,” said Dr. McCormick, a pediatric endocrinologist at the University of Alabama at Birmingham.

Some beneficial effects on glucagon were seen with the GABA–GAD combination. “At 12 months, fasting glucagon was reduced [P less than .013] in the GABA–GAD group, compared with placebo,” he said. This was a “novel observation,” because stimulated glucagon was also reduced in this cohort. “This could be a potential salutatory metabolic effect in diabetes.”

The data were the first to be reported from the trial, and results of the immunologic analyses should be available by the end of the year and might reveal more positive effects of GABA and GAD, Dr. McCormick suggested. Data from a “proinsulin analysis” will also be available later.

The inspiration for the trial was a study performed in mice showing that GABA exerted a protective and regenerative effect on the islet beta cells and “reversed diabetes” (Proc Natl Acad Sci USA. 2011;108:11692-7). It took almost 4 years from the publication of that study to enroll the first patient for the current study.

“GABA was intriguing ... first of all, it is available in health food stores and in supermarkets in the United States,” said Dr. McCormick. “It has a strong safety profile, it’s tasteless, and can be given orally – what better could you ask for in a trial of children with type 1 diabetes?”

GABA is thought to have multiple effects in the pancreas, from increasing insulin secretion and suppressing glucagon secretion, to altering inflammation and T-cell populations. “That’s what’s so important to emphasize, besides its metabolic effects, this compound also has immunosuppressant action,” Dr. McCormick noted.