In a blood test, high triglycerides mean that a person is at risk of heart disease or developing metabolic syndrome, according to WebMD. Metabolic syndrome raises a person's risk of developing diabetes, heart disease and stroke.
There are a number of conditions that cause high triglycerides including obesity, an underactive thyroid and diabetes that is not well controlled, explains WebMD. Other conditions that cause high triglycerides include kidney disease, overeating and drinking too much alcohol. Some medications also cause high triglycerides, and in some cases, the condition is hereditary. Losing weight, being more active, and limiting fats, sugar and alcohol in the diet all help reduce the number of triglycerides in the blood.