Patients given the most common treatment for kidney stones could be up to four times more likely to develop diabetes, according to research published yesterday.

Urologists in the US say they have found a "strong" association between a shock wave therapy - known as lithotripsy - and diabetes. They also appear to have confirmed a previously disputed link between lithotripsy and hypertension (high blood pressure), with those undergoing the procedure being 1½ times more likely to develop it. Around 40,000 people a year develop kidney stones in Britain, with 10% of men and 4-5% of women suffering the condition.

Around 15,000 a year will be treated with lithotripsy, which uses shock waves or ultrasonic waves to break down smaller stones so they can be excreted.

Scientists from the Mayo clinic in Rochester, Minnesota, found those given lithotripsy were 3.75 times more likely to develop diabetes, and 1.47 times more likely to develop hypertension, compared with those treated in other ways.

Amy Krambeck, the urologist who headed the study, published in the Journal of Urology, said: "We can't say with 100% certainty that shock wave treatment for kidney stones causes diabetes and hypertension, but the association is very strong." The team believes the increased diabetes risk is due to damage to the pancreas during lithotripsy, which may affect insulin production. The hypertension risk may relate to scarring to the kidneys, which could alter the secretion of hormones that influence blood pressure.

Victor Izegbu, a consultant urologist at the Central Middlesex hospital, London, said lithotripsy machines had been offering far more focused and less damaging treatment over the past eight years. "We don't believe the current generation of machines would cause any risk."