We all know that a lower cholesterol level is better, especially if you have diabetes. The most recent American Diabetes Association (ADA) guidelines recommend that people with diabetes maintain a low-density lipoprotein (LDL, or “bad”) cholesterol level below 100 mg/dl. There’s new evidence, though, that even lower levels offer even more protection.
Three recent studies indicate that intensive treatment of high LDL cholesterol with “statin” drugs lowers the risk of cardiovascular events (such as heart attacks and strokes) significantly. The subjects in the three clinical trials were given statins sufficient to lower their LDL levels as low as 54 mg/dl. LDL cholesterol is a key contributor to atherosclerosis, the “hardening of the arteries” that leads to heart disease, stroke, and peripheral vascular disease.
The latest word
The study known as the Pravastatin or Atorvastatin Evaluation and Infection Therapy–Thrombolysis in Myocardial Infarction 22 (PROVE IT–TIMI 22) trial compared a regimen of 40 milligrams (mg) of pravastatin daily (the standard therapy) with a more intensive regimen of atorvastatin at 80 mg a day. The participants in the study had already been diagnosed with an acute coronary syndrome (such as a heart attack), so this was a secondary prevention trial.
Those participants who reached LDL levels of 70 mg/dl or lower had significantly lower rates of second cardiac events. Among elderly participants, there was an 8% absolute lower risk of events and a 40% lower risk relative to those who did not achieve the target LDL levels. In younger people, the corresponding values were 2.3% and 26%.
The Incremental Decrease in End Points Through Aggressive Lipid Lowering (IDEAL) trial was similar in design, comparing a standard 20-mg-per-day dose of simvastatin to 80 mg per day of atorvastatin. The people in this secondary prevention trial had experienced a previous heart attack.
Participants on the more intensive atorvastatin therapy had an 11% reduction in relative risk of coronary death, heart attack, or cardiac arrest with resuscitation. This was not considered statistically significant, but there was a statistically significant reduction of 17% in nonfatal heart attacks.
The largest of the recent trials was the Treating to New Targets (TNT) study, which enrolled 10,000 people in 14 countries who had previously had a heart attack, had previous or current angina (chest pain associated with insufficient oxygen reaching the heart muscle), or had previously had a coronary bypass or angioplasty procedure. The participants were given either a moderate, 10-mg-per-day dose of atorvastatin or an 80-mg-per-day dose.
At the end of the five-year study, participants on the higher dose of atorvastatin had a reduction of 22% in cardiovascular death, heart attack, and stroke.
The diabetes connection
These studies were all focused on secondary prevention—that is, preventing more events in people who had already had a heart attack or other problem. So why are they relevant to people with diabetes who have not had a cardiac event?