Alpha-lipoic acid
Alpha-lipoic acid is a sulphur-containing compound the body also makes in small amounts, where it acts as a cofactor for mitochondrial enzymes and as an antioxidant that can regenerate other antioxidants. It is sold over the counter and taken mainly for symptoms of peripheral neuropathy and as general liver support. It is a supplement rather than a treatment for the underlying cause of nerve damage.
Absorption drops when it is taken alongside a meal, so it is usually taken on an empty stomach in the morning. It has a mild glucose-lowering effect of its own, which is why it is listed as interacting with metformin and with insulin glargine: combined with either, blood sugar can fall further than expected. Glucose and HbA1c are the values worth watching while it is used, particularly in the first weeks or after any change in diabetes treatment.
Sweating, shakiness, confusion or faintness suggest blood sugar has dropped too low and should be discussed with a doctor rather than managed by adjusting prescribed diabetes medication alone. A rash, or neuropathy symptoms that worsen instead of easing, also warrant a review.
Reference information, not medical advice. Discuss any change with your doctor.