Terrified he’ll die from diabetes or high blood pressure, “American Idol 2” winner Ruben Studdard is making a last-ditch effort to lose weight.

The soul crooner — who has tipped the scales at 450 pounds in the past — has already dropped 50 pounds off his massive 6-foot-4 frame, but doctors say the 28-year-old won’t be in the clear until he’s under 300 pounds.

“Being overweight causes health issues, and I don’t want any of them,” Ruben said recently. “I don’t want to be diabetic. I don’t want high blood pressure. I don’t want to have bad cholesterol.”

For four weeks this summer, Ruben attended a $7,000 weight-loss program at Duke Diet & Fitness Center at Duke University in Durham, N.C.

“Ruben has struggled with a weight problem for years,” said an insider. “But in the past few months, he finally got the message that he could wind up in the hospital or even die because of his size.

“At Duke, they helped Ruben change the way he eats and put him on a personally designed workout regimen.”

In addition to diabetes and heart trouble, the portly performer also wants to avoid developing reflux laryngitis — a condition often associated with obesity — which could destroy his voice and end his career.

“Ruben and his doctors agreed that if he didn’t start making some permanent changes, he was going to wind up in an early grave,” added the insider.

Now, Ruben says his daily routine includes two 45-minute cardio workouts and a specially tailored low-calorie, low-sodium diet.

“Ruben is keeping to the program every day, except for show days,” explained the insider.

“Ruben knows that this is a life-or-death situation for him, and he wants to keep on living.”