The BCG vaccine against tuberculosis can reverse Type 1 diabetes to almost undetectable levels, an eight-year study has shown.

US researchers found that just one jab, followed by a booster four weeks later, brought down average blood sugar levels to near normal within three years, and the effect lasted for the following five years.

British experts hailed the results as "very exciting" and said such a treatment would be a "major advance" in the treatment of Type 1 diabetes.

Type 1 diabetes is an autoimmune disease where the body attacks cells in the pancreas which produce insulin. Insulin is needed to move sugar from the blood to cells where it is used as energy and without regular top-up injections, patients can fall into a lethal coma.

About 400,000 people are living with the condition in Britain and need daily injections of insulin.