LDL PARTICLE-SIZE IN MILDLY HYPERTRIGLYCERIDEMIC SUBJECTS - NO RELATION TO INSULIN-RESISTANCE OR DIABETES

We examined 18 Type 2 diabetic and 19 non-diabetic subjects in order t o determine the association between insulin resistance and LDL particl e size distribution in mildly hypertriglyceridemic and hyperinsulinemi c subjects with and without Type 2 diabetes. Insulin sensitivity of th e patients was characterized by their insulin-stimulated glucose uptak e rate determined by euglycemic clamp technique. LDL particle size dis tribution was determined by nondenaturing polyacrylamide gradient gel electrophoresis. Type 2 diabetic and non-diabetic subjects had closely similar serum lipid and lipoprotein concentrations as well as the mea n particle diameters of the major LDL peak (246 +/- 6 Angstrom and 244 +/- 6 Angstrom, respectively). To evaluate the effect of insulin resi stance on LDL particle size the participants were categorized into two subgroups using the median of their insulin-stimulated glucose uptake rate (14.67 mu mol/kg/min) as a cut-off point. Neither lipid and lipo protein concentrations nor the LDL particle size distributions differe d between the more insulin resistant group (nine diabetic and nine non -diabetic subjects) and less insulin resistant group (nine diabetic an d ten non-diabetic subjects), LDL particle size was not associated wit h the insulin-stimulated glucose uptake rate or with the mean 24-h con centration of serum insulin. Mean 24-h concentration of serum triglyce rides was the strongest discriminator for LDL particle size (r = -0.44 , P < 0.01). In conclusion, neither Type 2 diabetes nor insulin resist ance seem to have any direct effect on LDL particle size in mildly hyp ertriglyceridemic subjects. The fact that LDL particle size was associ ated with serum triglycerides indicates that the effect of diabetes an d insulin resistance on LDL particle size could be explained by the ef fects of insulin resistance and/or hyperinsulinism on VLDL metabolism.