Plasma lipid levels and apolipoprotein C (apo C) composition of VLDL were investigated in a group of Type 2 diabetic patients at first attendance at the outpatient clinic and before any therapeutic intervention. Patients were distributed into two groups of 26 individuals, normo- and hyperlipidaemic, respectively, and compared with two matched control groups. Normolipidaemic diabetic patients had higher serum triglycerides, VLDL cholesterol, and lower HDL cholesterol than matched normolipidaemic control subjects. While hyperlipidaemic non-diabetic individuals showed increased apo C II and decreased apo C III-1 percentages when compared with normolipidaemic non-diabetic individuals (12.1 +/- 4.9 vs 8.5 +/- 3.2% and 44.0 +/- 6.7 vs 48.1 +/- 7.0%, respectively, mean +/- SD, both with p less than 0.05), the relative distribution of apo C III isoforms and apo C II was similar in both normo- and hyperlipidaemic diabetic patients.