The number of triglycerides in the human body can rise to abnormally high levels when someone eats a diet that is high in carbohydrates (starches and sugars) and/or saturated fats. Triglycerides are usually especially high in people who are obese or who rarely exercise.

High triglyceride levels can also be caused by a number of medical conditions and other factors, such as:

• Diabetes
  
  
• Hypothyroidism, or a lack of thyroid hormone
  
  
• Kidney disease
  
  
• Certain medications, including tamoxifen (used in cancer treatment) and estrogen replacement therapy
  
  
• Familial hyperlipoproteinemias. Rare genetic conditions that involve high levels of cholesterol and/or triglycerides. Some studies have associated genetically elevated levels of triglycerides with an increased risk of heart disease, but others have not.
  
  
• Familial hypertriglyceridemia (also known as type IV hyperlipoproteinemia). Genetic condition in which triglyceride levels are abnormally high. It is often accompanied by insulin resistance, obesity, overactive thyroid and high blood pressure.
  
  
• Familial dysbetalipoproteinemia (also known as familial combined hyperlipoproteinemia). Genetic condition in which levels of triglycerides and cholesterol are abnormally high.
  
  
• Familiar lipoprotein lipase deficiency or Apo-C-II deficiency. Genetic condition in which people lack one of the enzymes necessary to properly break down chylomicrons. As a result, the person may be diagnosed with a high chylomicron level (also known as hyperchylomicronemia or chylomicronemia syndrome or type I hyperlipoproteinemia).
  
  
• Type III hyperlipoproteinemia, a combination of high triglycerides and high levels of very low-density lipoproteins (VLDL).
  
  
• Type V hyperlipoproteinemia, the inability to use and rid the body of triglycerides, leading to high levels of triglycerides in the plasma.