Previous research outside the United States has linked high levels of arsenic in drinking water with diabetes. It's the link at low levels that's new.
The analysis of the medical tests of 788 adults found a nearly fourfold increase in the risk of diabetes in people with low arsenic concentrations in their urine compared to people with even lower levels.
How arsenic could contribute to diabetes is unknown. But prior studies have found impaired insulin secretion in pancreas cells treated with an arsenic compound.
The study's limitations make more research necessary. And public water systems were on their way to meeting tougher U.S. arsenic standards as the data were collected.
The findings appear in the Journal of the American Medical Association.