13 Pages

Insulin resistance and CHD

Insulin resistance is tissue resistance to insulin

action, whether this is in terms of glucose or

lipid metabolism, or the vasodilatory actions

of insulin. Insulin resistance is usually

accompanied by hyperinsulinaemia. Insulin

promotes smooth muscle cell proliferation and

arterial lipid deposition, and hence may be

Insulin resistance has conventionally been

defined as the change in glucose elimination

rate elicited by a unit change in insulin

concentration. It is difficult to quantitate, and

only two methods used in clinical practice

provide a true measure of insulin sensitivity

(the inverse of insulin resistance).9 These are

the euglycaemic hyperinsulinaemic clamp and

the minimal model analysis of glucose and

insulin profiles obtained during an

intravenous glucose tolerance test (IVGTT),

and the two methods correlate closely with

each other.10 The euglycaemic

hyperinsulinaemic clamp utilizes a constant

intravenous infusion of insulin and a varying

intravenous infusion of glucose. Though it

gives a true estimate of insulin sensitivity, the

method is extremely labour intensive and time

consuming, and it is also non-physiological.