1. To investigate the acute effects of insulin and triacylglycerol (‘triglyceride’) on circulating plasminogen activator inhibitor-1 concentrations, seven healthy volunteers were studied during hyperinsulinaemic clamps in the presence of euglycaemia (mean glucose concentration 5 mmol/l) and hyperglycaemia (mean glucose concentration 9 mmol/l) with and without triacylglycerol infusions.
2. During euglycaemia, plasma insulin levels rose from baseline values [median (range)] of 13 (6.6–20.6) m-units/l to 89 (74–105) m-units/l and 99 (74–109) m-units/l after 1 and 2 h of insulin infusion, respectively. Concentrations of plasminogen activator inhibitor-1 fell from 27.5 (10–47) ng/ml to 25.0 (14.5–55) ng/ml and 15.5 (11.5–28.5) ng/ml (P < 0.02) over the same time.
3. During hyperglycaemia, plasma insulin concentrations were 12.1 (9.3–17.1) m-units/l at the run-in period and rose to 87 (73–112) m-units/l and 91 (84–97) m-units/l after 1 and 2 h of insulin infusion, respectively. Concentrations of plasminogen activator inhibitor-1 again showed a gradual fall from 24.7 (22–50) ng/ml to 14 (8.3–25.5) ng/ml and 13 (6.0–35.0) ng/ml (P < 0.02) over the same period.
4. Infusion of Intralipid in the presence of hyperinsulinaemia with either euglycaemia or hyperglycaemia was associated with a similar fall in concentrations of plasminogen activator inhibitor-1 over the study period.
5. The results from this study indicate that short-term increases in insulin, glucose or triacylglycerol do not cause acute increases in plasma concentrations of plasminogen activator inhibitor-1.