The objective of the CARE study was to assess the effect of a statin on the risk of a fatal or non-fatal heart attack in people with coronary heart disease and high cholesterol levels. 14% of the participants had diabetes. The study demonstrated a 25% reduction of major coronary events in people with diabetes being treated with the statin. Total cholesterol levels were cut by 19%, LDL cholesterol by 27%, triglycerides by 13%, and HDL cholesterol was increased by 4%.
The DCCT is a clinical study conducted from 1983 to 1993 by the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The DCCT involved 1441 volunteers who had type 1 diabetes for at least 1 year but no longer than 15 years. They also were required to have no, or only early signs of, diabetic eye disease.The study compared the effects of two treatment regimens - standard therapy and intensive control - on the complications of diabetes. Volunteers were randomly assigned to each treatment group. The study showed that keeping blood glucose levels as close to normal as possible slowed the onset and progression of diabetic eye, kidney, and nerve diseases.
The objective of the DIGAMI study was to determine the long-term effect of intensive insulin treatment initiated at the time of an acute heart attack on 620 people with diabetes. Patients were randomly assigned to either intensive insulin treatment or standard treatment. During an average follow-up of over three years a significant mortality risk reduction (24%) was recorded in the intensively treated group.
The HOT study is the largest trial ever conducted of the results of treating hypertension. 18,790 patients from 26 countries were followed up for an average of just under four years. 8% of the patients had diabetes. HOT’s objective was to find out how far blood pressure should be lowered using antihypertensive drugs in order to achieve the maximum decreases in strokes and heart attacks in people with hypertension. Compared to the people with diabetes in the group with diastolic blood pressure kept at 90 or below, those in the group 80 or below had a 51% reduction in major cardiovascular events and a 30% reduction in strokes.
The WHO MONICA Project is the largest community-based study on heart disease ever undertaken. The results show that heart disease rates are related to changes in major coronary risk factors and to the introduction of new medical treatments. More than seven million men and women aged between 35 and 64 years of age were monitored to examine if and how certain coronary risk factors and new treatments for heart disease contribute to the rise or fall of heart disease rates in these communities.
Risk factors such as cigarette smoking, blood pressure, blood cholesterol and body weight were studied by MONICA. Treatments taken into consideration included aspirin, beta blockers, ACE-inhibitors, clot dissolving agents and coronary artery surgery.Heart disease rates fell in most of the populations studied, as did cigarette smoking in men, blood pressure and blood cholesterol. Smoking in women showed a mixed picture and weight rose in both men and women in most populations.
Taking all populations as a whole, the decline in smoking seems to have contributed most to the reduction in the risk of heart disease in men. In women, the decrease in blood pressure emerged as the strongest determinant. Overall, it was found that the relation between the fall in heart disease rates and the change in risk factors was more apparent in men than in women.
The objective of the diabetes sub-study of the 4S was to assess the effect of a statin on mortality and the risk of a major coronary event in people with coronary heart disease and high cholesterol levels. 5% of the total participants had diabetes. The study found that major coronary events were halved in people with diabetes being treated with statin therapy. Total cholesterol was reduced by 27%, LDL cholesterol by 36%, triglycerides by 11%, and HDL cholesterol was increased by 7%.
The UKPDS recruited 5102 patients with newly-diagnosed type 2 diabetes in 23 centres within the UK between 1977 and 1991 and followed them for 10 years. The study confirmed that when people with type 2 diabetes aggressively lowered blood glucose (maintaining HbA1c levels around 7%), their risk of blindness and kidney failure fell by 25%. In a group of overweight people treated with an oral hypoglycaemic agent (metformin) the impact on microvascular complications was not as strong, but there was a significant reduction in the risk of a fatal or non-fatal heart attack (37%) and all-cause mortality (36%). When high blood pressure was aggressively tackled, major reductions in the risk of stroke (44%) and heart failure (56%) were achieved in addition to the eye and kidney benefits.
The objective of the VA-HIT study was to assess the effect of fibrate theraphy on mortality and the risk of a major coronary event in people with coronary heart disease and near-normal LDL cholesterol but low HDL cholesterol. 25% of the participants had diabetes. The study found that by increasing HDL cholesterol by just under 8% and decreasing triglycerides by 25%, the risk of a major cardiovascular event was cut by 22% in people with diabetes. This was the first trial to demonstrate a diminished risk of cardiac events from an intervention that raised HDL levels but did not reduce LDL levels.