Patients at the Buffalo VA Hospital are finding out that they may have been exposed to the HIV virus, hepatitis, or other blood-borne diseases, all because of a major hospital mix-up involving insulin pens that nurses at the hospital were reusing on multiple patients.

"I started having major health issues," said a veteran who we're calling "Joe," who didn't want his identity revealed.

He served in the US Army right out of High School decades ago. Joe now relies on the free medical care he receives from the VA Hospital in Buffalo. He has always been happy with the hospital until now.

"I received a call from one of the nurses that's at VA," said Joe. "She informed me that I needed to come in for blood work."

Joe found out he is on the list of 540 veterans who received insulin shots at the Buffalo VA and may have been exposed to HIV or hepatitis.

"It caught me out of left field you know. Wasn't expecting that," he said.

While in the hospital, Joe received insulin from an insulin pen. The needles in the pens were changed, but the hospital says nurses were using the same pens on multiple diabetic patients.

Although the chance for infection is small, it's enough to send Joe and his family into panic.

"Scares the heck out of me," said Joe. "The stress. I don't think anybody can even understand laying in bed last night thinking what if?"

Hospital officials say they will review practices and make changes to make sure this never happens again.

"We always look to ensure patient safety," said Buffalo VA Hospital Chief of Medicine Dr. Donald McDonald. "We always look to ensure we are transparent to provide the best care possible."

For vets like Joe who suspect this health scare is the result of years of improper oversight, there's now real concern about the quality of the care the VA Hospital can provide.

Joe is scheduled to undergo testing this week and hospital officials say all 540 people should be tested by the end of the month.