A woman has been cured of diabetes thanks to a donor transplant of insulin-producing cells from her mother.
Many people with diabetes must have regular insulin shots
Three months after the operation at Japan's Kyoto University Hospital, both mother and daughter are fit and well.
It is the first time an islet cell transplant from a living donor has worked, the doctors told The Lancet.
Islet cells have previously been taken from dead donors, but the cells were often damaged, hampering their success.
Last month, a 61-year-old man became the first person in the UK to be cured of type 1 diabetes in this way.
Dr Shinichi Matsumoto and colleagues said islets from living donors have the advantage of being more viable and more likely to function properly.
Also, there are many more potential donors than with islet cells from the deceased.
Two or more whole pancreases from dead donors are needed for an islet transplantation, compared to just half of a living pancreas, experts have found.
Two previous attempts at transplantation from living donors have been carried out in the US, but were unsuccessful.
Taking donor cells from a close relation reduces the risk of rejection of the transplanted cells by the recipient.
However, the woman still has to take powerful drugs to stop her rejecting the new cells, said her doctors.
In diabetes, blood sugar is too high because the body cannot use it properly.
This is because the hormone insulin, which enables the body to control blood sugar levels, is either not produced by islet cells in the pancreas or does not work properly.
People with the condition must regularly boost insulin levels, either by injection or by wearing a pump which dispenses the hormone under the skin.
For the transplant, healthy islet cells are taken from donor pancreases and injected into the patient's liver.
Once there, they develop their own blood supply and begin to produce insulin.
The 27-year-old woman developed insulin-dependent diabetes when she was 15 after having chronic pancreatitis.
After receiving the living donor islet cells from her 56-year-old mother, she now no longer has to take insulin.
She has been free of her daily insulin injections for the past two months.
Although it is still early days, the doctors believe that the transplant could last up to five years.
Specialist Professor Stephanie Amiel, from King's College London, cautioned that islet transplantation was not yet a perfect technique and that insulin independence was "by no means certain."
She pointed out that the mother who had donated some of her pancreas to her daughter had, in turn, put herself at increased risk of diabetes.
Dr Angela Wilson, director of research at Diabetes UK, said: "The success of this groundbreaking operation is exciting news.
"There are very few donor pancreas which is a major problem for islet cell transplants.
"However, this is the first operation of its kind and we will be following the progress of this patient and any future live transplants very closely.
"The health of the donor is also an important factor. Donors are put at considerable risk from the surgery itself."