The researchers collected information on patients' control of blood sugar at the start of the study. They used hemoglobin A1c levels less than 6.5% and less than 7% to define tight control. The researchers collected information from patients on their history of heart disease, lung disease, heart failure, urinary tract disease, arthritis, foot problems, and digestive conditions and classified them as having low to moderate or high levels of other health problems. They then followed patients for about 5 years to see who developed new cardiovascular events.