Vitamin B1 (thiamine), which is found in meat, yeast and grain, could benefit people with diabetes, research has found.
Researchers from Warwick University tested the effect of vitamin B1 on 40 patients from Pakistan, which stopped the loss of a key protein in the urine.
According to the researchers, this inexpensive and available supplement could benefit most people with diabetes - as between 70% and 90% of people with diabetes are thiamine deficient.
The charity Diabetes UK called the results "very promising" - but said it was too early for any firm conclusions.
Lead researcher Professor Paul Thornalley said: "This is the first study of its kind and suggests that correcting thiamine deficiency in people with diabetes with thiamine supplements may provide improved therapy for early-stage kidney disease."
In diabetes the small blood vessels in the body can become damaged. When the blood vessels that supply blood to the kidneys are involved, the kidneys stop working correctly and important proteins, such as albumin, are lost from the blood into the urine.
A third of the patients in the study saw a return to normal urinary albumin excretion after being treated with high dose (300 mg) thiamine taken orally each day for three months.
Researchers said thiamine works by helping protect cells against the harmful effects of the high blood sugar levels found in diabetes.