Borderline high triglycerides = 150 to 199 mg/dL. High triglycerides = 200 to 499 mg/dL. Very high triglycerides = 500 mg/dL or higher. High triglyceride levels may lead to heart disease, especially in people with low levels of good cholesterol and high levels of bad cholesterol, and in people with type 2 diabetes. Experts disagree, though, on just how bad of an effect high triglyceride levels by themselves have on the heart.