Research - Soinio

High Homocysteine Levels Increase Risk for Heart Attacks in People with Type 2 Diabetes Mellitus

What is the problem and what is known about it so far?
Heart attacks remain leading causes of death and disability in most western countries. Smoking, high-fat diet, high cholesterol level, high blood pressure, diabetes and kidney disease increase a personÕs risk for coronary heart disease and heart attacks. Recently, researchers identified several additional risk factors for heart disease. One of them is homocysteine level. Homocysteine is an amino acid that may be increased when the intake of vitamins, such as folic acid is low. Most studies that show high homocysteine levels increase the risk for heart attacks were in patients who already had coronary artery disease and did not have diabetes. Few studies address whether homocysteine level increases risks for heart attacks in people with diabetes mellitus.

Why did the researchers do this particular study?
To whether high levels of homocysteine increase risks for heart attacks in adults with type 2 diabetes.

Who was studied?
830 Finnish men and women, 45 to 64 years of age, with type 2 diabetes

How was the study done?
Researchers identified adults with diabetes from a Finnish national drug registry. Between 1982 and 1984, they measured each personÕs blood pressure and weight. They asked about smoking habits, alcohol intake, physical activity, medications and chest pain. They took blood tests to measure levels of homocysteine, glucose, cholesterol and other lipids, and creatinine (a measure of kidney function). They also used blood tests (C-peptide values) to see which patients had type 1 and type 2 diabetes. Seven years later, the researchers reviewed death certificates and medical records to see whether anyone had died of or had been hospitalized with a heart attack. They then examined whether the heart attacks occurred more often in persons who had high homocysteine levels 7 years previously.

What did the researchers find?
High levels of homocysteine (plasma homocysteine ³15 µmol/L) were associated with increased risk for fatal and nonfatal heart attacks, even after accounting for several other risk factors. High homocysteine levels also increased risks for death from heart attack.

What were the limitations of the study?
Researchers used a drug registry to identify study participants. Healthier people with early or less severe type 2 diabetes might not be listed in the registry. The study did not measure folate intake or changes in risk factors over time. It cannot tell us whether lowering homocysteine level with higher folate intake would reduce coronary artery disease.

What are the implications of the study?
Homocysteine is an independent risk factor for heart attacks in adults with type 2 diabetes.

Reference: Soinio M, et al. Elevated Plasma Homocysteine Level is an Independent Predictor of Coronary Heart Disease Events in Patients with Type 2 Diabetes Mellitus. Ann Intern Med. 2004; 140: 94-100.

HOMOCYSTEINE FACT:

Lowering homocysteine concentrations by 3 umol/l from current levels (achievable by increasing folic acid intake) would reduce the risk of ischaemic heart disease by 16%, deep vein thrombosis by 25%, and stroke by 24%.