Summary: In 35 men with long-standing type 1 diabetes (5 or more years), a phase I/II randomized trial of controlled-release oral GABA (Remygen) at 200 mg or 600 mg daily for 6 months produced no effect on fasting or stimulated C-peptide, CGM metrics, or HbA1c, and hypoglycaemic counter-regulation was unaltered. Elevated AST occurred in 9 subjects, prompting 2 withdrawals, so side effects were common and no beta-cell regenerative signal was seen.
PICO Summary
| Element | Detail |
|---|---|
| Population | 35 male adults with long-standing type 1 diabetes (5 or more years’ duration); phase I/II randomized controlled trial, single centre, Sweden. |
| Intervention | Controlled-release oral GABA (Remygen, Diamyd Medical) once daily for 6 months. Arm 1: GABA 200 mg. Arm 2: GABA 600 mg. Arm 3: GABA 600 mg plus alprazolam 0.5 mg for 3 months, then GABA 600 mg alone for 3 months. Roughly 11 to 12 subjects per arm. |
| Comparison | Between-arm and within-subject comparison of GABA doses and the alprazolam-augmented arm; no separate placebo arm was described in the abstract. |
| Outcome | No effect on fasting or stimulated C-peptide, CGM metrics, or HbA1c, and hypoglycaemic hormonal counter-regulation was unaltered (no formal effect estimates, confidence intervals, or p-values reported in the abstract; no ARR/NNT applicable to a null efficacy result). Safety: elevated AST in 9 of 35 subjects, leading to 2 withdrawals; most elevations were transient with no dose-difference. Authors concluded no clinical evidence of a beta-cell regenerative effect, with side effects commonly observed. |
Expert Commentary
The verdict is a clean negative. Despite preclinical signals that GABA might promote beta-cell proliferation and insulin secretion, this phase I/II trial found no improvement in fasting or stimulated C-peptide, CGM metrics, or HbA1c, and counter-regulation during hypoglycaemic clamps was unchanged. The result should be read as exploratory and hypothesis-testing rather than as a definitive efficacy verdict, because it was small (35 participants across three arms), early-phase, and confined to men with long-standing disease, a group with minimal residual beta-cell mass in whom regeneration was always a tall order. The principal limitation is that this population is among the least likely to show a regenerative response, so a null finding here does not exclude benefit nearer to diagnosis. Safety deserves emphasis: aspartate aminotransferase rose in 9 of 35 subjects and forced 2 withdrawals, so the earlier framing of GABA as well-tolerated with minimal side effects was too generous. Industry involvement also warrants caution, since Remygen is made by the trial’s commercial developer. Can I use this with my patients? Not yet; there is no role for oral GABA to preserve or restore beta-cell function in established type 1 diabetes outside research. Future trials should test earlier intervention with rigorous liver monitoring.
References
Hill H, Lundkvist P, Tsatsaris G, Birnir B, Espes D, Carlsson PO. Long-term gamma-aminobutyric acid (GABA) treatment fails to regain beta-cell function in longstanding type 1 diabetes in a randomized trial. Sci Rep. 2025;15(1):11530. doi:10.1038/s41598-025-95751-y