Remygen (oral GABA) — Diamyd's beta-cell regeneration bet
Diamyd Medical (Uppsala University investigator-led trials)
Remygen is Diamyd Medical's controlled-release oral form of GABA, a molecule that in lab and animal studies coaxes beta cells to multiply and calms islet inflammation. It was tested as a stand-alone way to regrow insulin production in people with long-standing T1D. In the completed ReGenerate-1 trial it proved safe enough but showed no measurable beta-cell regeneration — making it an important, honestly negative human result rather than a working therapy.
The scorecard
In the completed adult ReGenerate-1 RCT, GABA produced no change in fasting or stimulated C-peptide, CGM metrics or HbA1c — no clinical evidence of beta-cell regeneration.[1]
With no measurable beta-cell gain to sustain over 6 months of dosing, durability is moot; any regrown cells would also still face ongoing autoimmunity.[1]
Generally tolerable, but nine of 35 adults had elevated liver enzyme (AST) levels and two withdrew; a separate pediatric GABA/GAD trial confirmed broad tolerability.[1]
A cheap oral pill would in principle reach almost anyone, but it showed benefit in no one — and the regeneration premise needs residual beta cells to act on.[2]
Reached completed, registered phase I/II human trials (NCT03635437) — further than most regeneration ideas — but those trials read out negative for beta-cell function.[3]
The full picture
GABA is the molecule that, in dishes and mice, ticks every box you would want from a beta-cell regeneration drug: it nudges beta cells to multiply, boosts insulin release, dampens alpha-cell glucagon, and quiets islet inflammation. Diamyd Medical built a controlled-release oral form, Remygen, to test whether that promise carries into people. ReGenerate-1, run at Uppsala University, gave Remygen once daily for six months to adults who had lived with T1D for at least five years and had little or no insulin production left — exactly the group a true regeneration drug would need to help.
The honest result: it did not work as a regenerative therapy. Fasting and meal-stimulated C-peptide, continuous-glucose metrics and HbA1c were all unchanged, so there was no sign that beta cells came back. Side effects were common, including transient liver-enzyme rises in nine of 35 participants, two of whom withdrew. An earlier pediatric trial of oral GABA, alone or with the GAD-alum vaccine, in newly diagnosed children likewise missed its goal of preserving C-peptide, though it confirmed GABA's safety. The leading explanation is that the doses were too low or the formulation too short-acting to reproduce the lab effect. Remygen matters here as a cautionary, well-documented negative — a reminder that elegant mouse biology often stalls in humans.
Coming soon
ETA · No regenerative effect seen in the completed phase I/II trial; no further regeneration trial of GABA announced. Not a near-term therapy.
- →Higher-dose or longer-acting GABA formulations (suggested by investigators, not yet trialled)
- →GABA paired with antigen-specific immunotherapy (e.g. GAD-alum) rather than used alone
Sources
- [1]Long-term gamma-aminobutyric acid (GABA) treatment fails to regain beta-cell function in longstanding type 1 diabetes in a randomized trial · peer-reviewed · 2025-01-01
- [2]A randomized trial of oral GABA or the combination of GABA with glutamic acid decarboxylase (GAD) on pancreatic islet endocrine function in children with newly diagnosed type 1 diabetes · peer-reviewed · 2022-01-01
- [3]ReGenerate-1: Evaluation of Safety and Diabetes Status Upon Oral Treatment With GABA in Patients With Longstanding Type-1 Diabetes (NCT03635437) · registry · 2018-01-01