Insulin Resistance, Not Hyperglycemia, Predicts
CAD in Type 1 Diabetes
Traditional risk factors appear to be more important
than glycemic control in predicting coronary artery
disease (CAD) among patients with type 1 diabetes.
That, according to results of the prospective Pittsburgh
Epidemiology of Diabetes Complications (PEDC) Study.
"
The good news is that not all people with type 1
diabetes are insulin resistant, and for them the
risk of heart disease may not be as high," lead
author Dr. Trevor J. Orchard commented in a University
of Pittsburgh Medical Center press release. However, "reducing
or preventing insulin resistance through exercise,
weight loss and possibly medication may help people
with type 1 diabetes avoid heart disease," he
adds.
Between 1986 and 1988, Dr. Orchard's group examined
603 subjects with type 1 diabetes, mean age 28
years, who were free of prevalent CAD. They
discuss their
findings in the May issue of Diabetes Care.
During 10 years of follow-up, incident CAD events
occurred in 108 subjects. These included 5 CAD
deaths, 25 nonfatal MIs, 12 cases of coronary
stenosis of
50% or greater, 49 cases of angina and 17 of
ischemic ECG changes.
Diabetes duration, hypertension, WBC, HDL-cholesterol,
non-HDL cholesterol and smoking history independently
predicted CAD. The average estimated glucose
disposal rate, which is based on HbA1, waist/hip
ratio and
hypertension, was lower in patients with incident
CAD and was an independent predictor of CAD,
MI, and coronary stenosis.
There was no positive association between hemoglobin
A1 (HbA1) and CAD, a finding that the authors
call "concerning
and intriguing." They point out that earlier
research has indicated a relationship between HbA1
and lower extremity arterial disease (LEAD).
Therefore, they theorize that "though hyperglycemia
leads to more extensive atherosclerosis, the plaques
so formed are more stable and thus less likely to
rupture and case acute coronary events."
"
The prediction of angina by greater smoking and depressive
symptoms (and possibly lower HbA1) raises the possibility
that a certain subset may have a susceptible... underlying
psychological state that might exacerbate any tendencies
to coronary artery spasm and is associated with smoking
and possibly increased concern about blood sugar
control," the EDC investigators add. Diabetes
Care 2003;26:000-000.
