New Delhi, April 11: A common shock wave treatment to painlessly pulverise stones in the kidneys is associated with an increased risk of diabetes and high blood pressure, medical researchers have reported.

A study by researchers at Mayo Clinic in the US has found that the risk of developing diabetes after shock wave therapy for kidney stones is almost four times the risk in people who received other treatment for their kidney stones.

The US researchers, who investigated the health of several hundred people who had received shock wave therapy in 1985, also found that high blood pressure was more common among such patients.

“This is a completely new finding,” said Amy Krambeck, the study’s principal investigator. “We can’t say with 100 per cent certainty that shock wave treatment caused diabetes and high blood pressure, but the association is very strong,” said Krambeck, who’s the lead author of a research paper describing these findings published in the May 2006 issue of the Journal of Urology.

Since shock wave treatment was introduced in the mid-1980s, urologists estimate several million people around the world have undergone the procedure in which shock waves turn stones into sand-like particles that are expelled in urine.

Some urologists have questioned the link between shock waves and diabetes or high blood pressure. “An association between two things does not prove a cause-effect relationship,” said Dr Nitin Kekre, a senior urologist at the Christian Medical College in Vellore and editor of the Indian Journal of Urology.

“At this point, all we can say is that we need more such studies from other centres around the world,” he said.

Shock wave therapy is typically used to treat kidney stones less than 2.5 cm in size or stones in the ureter less than 1.5 cm in size. “It’s a painless procedure that has helped millions of patients avoid alternative traumatic surgery,” Kekre said.

“It would be a great pity if a scare was created on the basis of data from a single centre.”

The urologists at Mayo Clinic said they continue to offer shock wave treatment to patients with kidney stones, but counsel their patients about the potential risk for diabetes and high blood pressure before the therapy.

“It’s a trade-off about whether the risks are worth taking,” said Mayo Clinic urologist Joseph Segura. “You have to look at it in terms of treatment alternatives... each of which has its own set of risks,” a news release from the clinic quoted Segura as saying.

In alternative procedures, doctors remove kidney stones with an instrument inserted into the kidney through a small incision in the back, or break up the stones with laser energy delivered through an instrument inserted through the bladder.

The Mayo researchers found that the risk of diabetes appeared to rise with greater number of shocks and treatment intensity. They hypothesise that shock wave therapy might affect insulin-secreting islet cells in the pancreas and raise the risk of diabetes, cause scarring in kidneys and raise the risk of high blood pressure.