Triglycerides are a type of fat in the bloodstream and fat tissue. Too much of this type of fat can contribute to the hardening and narrowing of your arteries. This puts you at risk of having a heart attack or stroke. Diseases such as diabetes, obesity, kidney failure or alcoholism can cause high triglycerides. Often, high triglycerides occur along with high levels of cholesterol, another type of fat. Triglycerides are measured along with cholesterol as part of a blood test. Normal triglyceride levels are below 150. Levels above 200 are high.