The role of the intestine in
cholesterol metabolism in human diabetes is unclear, although abnormalities have been demonstrated in
cholesterol synthesis and absorption in diabetic animals. This study examines the relationship between fasting and post-prandial
apolipoprotein B-48 in type 2 (non-
insulin-dependent) diabetic and non-diabetic subjects. Eight type 2 diabetic patients and ten healthy non-diabetic control subjects were given a high-fat meal (1300 kcal), and the
triglyceride-rich
lipoprotein fraction was isolated by ultracentrifugation (d < 1.006 g/ml) from fasting and post-prandial plasma.
Apolipoprotein B-48 and
apo B-100 were separated on 4%-15% gradient
gels and quantified by densitometric scanning with reference to a purified
low-density lipoprotein (
LDL)
apo B-100 preparation. Diabetic patients had significantly higher concentrations of
apo B-48 and
apo B-100 in both the fasting (P < 0.05) and post-prandial (P < 0.001)
triglyceride-rich
lipoprotein samples compared with non-diabetic subjects. The diabetic patients also exhibited a significantly different post-prandial profile for
apo B-48 and
apo B-100, with a prolonged increase and a later post-prandial peak, than the non-diabetic subjects (P < 0.01). These results suggest that the raised fasting
triglyceride-rich
lipoproteins, often found in diabetes, are associated with
apo B-48 and may be derived from increased intestinal
chylomicron production. The post-prandial pattern suggests an abnormality in intestinal production as well as hepatic clearance of
apo B-48 in
type 2 diabetes.