Researchers identified adults with diabetes from a Finnish national drug registry. Between 1982 and 1984, they measured each person's 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.