Nassau University Medical Center has issued a warning to patients that were treated at the hospital for diabetes.The hospital says that doctors may have used insulin pens on multiple patients. Steven Walerstein, NUMC's medical director, says some nurses thought they saw the pens being used on more than one patient. The hospital stopped using the insulin pens, investigated and found no evidence that multiple use actually occurred. Erring on the side of caution, the hospital says it notified the state's Department of Health and will be sending letters to 185 patients that may be affected. If the pens were reused, it would increase the risk of getting Hepatitis C, Hepatitis B and HIV. Walerstein says there have been no reports of infected patients so far. In the meantime, Walerstein says the hospital has gone back to a more traditional insulin delivery system. Patients with questions are asked to call 516-296-4333.Click for more on safety and medical instruments.