Important contribution of lipoprotein particle number to plasma triglyceride concentration in type 2 diabetes

The aim of the present study was to determine the contributions of particle size versus number to differences in plasma triglyceride-rich lipoprotein concentrations in patients with type 2 diabetes. Fasting plasma was obtained from 174 consecutive eligible men and women with type 2 diabetes (with or without insulin treatment, mean age 57.0 + 6.3 years) who were undergoing coronary angiography. The triglyceride-rich (Sf 12-400) lipoproteins (TRL) were subfractionated into the Sf 12-60 and Sf 60-400 subfractions. Particle numbers, estimated by measuring apolipoprotein B by electroimmunoassay, in each of these lipoprotein fractions were related to enzymatically determined triglyceride levels in the triglyceride-rich lipoproteins. Approximately 87% of the triglyceride-rich lipoprotein particles were in the Sf 12-60 fraction and 13% in the Sf 60-400 fraction. Multiple linear regression indicated that 69% (i.e. r2=0.69) of the variance in the triglyceride levels could by explained by differences in TRL particle number and 17% (i. e. r2=0.17) by the differences in particle triglyceride content. These observations are similar in each gender and in those with or without insulin treatment. In conclusion, in type 2 diabetes, the vast majority of triglyceride-rich lipoproteins are smaller particles which are in the Sf 12-60 fraction. Differences in particle number, rather than triglyceride content, account for approximately 70% of the differences in triglyceride levels observed between individuals. Previous demonstrations, in those without diabetes, of an association between small triglyceride-rich lipoproteins with coronary artery disease suggest the importance of these findings to the increased atherosclerosis in diabetes.