Intraperitoneal insulin infusion improves the depletion in choline-containing phospholipids of lipoprotein B particles in type I diabetic patients

Abstract

Insulin-dependent diabetes mellitus (IDDM) is characterized by altered composition of atherogenic lipoproteins, especially a depletion in choline-containing phospholipids (PL) of apolipoprotein (apo) B lipoproteins (LpB). To determine the effects of continuous intraperitoneal (IP) insulin infusion (CIPII) on this qualitative lipoprotein abnormality, we compared lipoprotein profiles of 14 IDDM patients treated by continuous subcutaneous insulin infusion (CSII) and at 2 and 4 months after treatment with CIPII using an implantable pump. IDDM patients were in fair metabolic control and were compared with 14 healthy control subjects matched for sex, age, body mass index, and plasma lipids. The following parameters were studies: hemoglobin A1c (HbA1c), monthly blood glucose, daily insulin dose (units per kilogram per day), total cholesterol (TC), triglycerides (TG), high-density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, apo A-I, and apo B. Choline-containing PL were assessed in plasma and in apo B- and no-apo B-containing lipoprotein particles (LpB and Lp no B). As compared with the control group, plasma PL and LpB-PL were significantly lower in IDDM patients treated by CSII (2.95 +/- 0.26 v 3.30 +/- 0.45 mmol/L,P<.05, and 1.09 +/- 0.45 v 1.68 +/- 0.33 mmol/L,P<.01, respectively). No significant differences were observed for Lp no B lipid determinations between both groups. After initiation of CIPII, IDDM patients did not experience any significant changes in mean values for body mass index, HbA1c, and monthly blood glucose throughout the study. Daily insulin doses were identical to those observed before IP therapy. Lipid parameters remained unchanged in IDDM patients (TC, TG, HDL and LDL cholesterol, apo A-I, and apo B). A moderate but progressive elevation of plasma PL was noted, and after 4 months of CIPII, PL and LpB-PL levels were no longer significantly different between IDDM patients and controls. The increase in plasma and LpB choline-containing PL observed after 2 and 4 months of CIPII is not linked to changes in blood glucose control, body weight or daily insulin requirements. These changes may be related to the route of insulin administration, which may be accompanied by a reduction of lipoprotein lipase (LPL) activity and consequently a reduction of phospholipase activity. These results suggest that IP insulin delivery may be a more physiological route that increases the choline-containing PL content of LpB particles.