Insulin-like growth factors and binding proteins in patients with recent-onset type 1 (insulin-dependent) diabetes mellitus: influence of diabetes control and intraportal insulin infusion.

Type 1 diabetes mellitus is associated with decreased insulin-like growth factor-1 (IGF-1) levels, enhanced values of growth hormone (GH) and IGF-binding protein 1 (IGFBP-1). Since the liver is the major source of IGF and IGFBP production, we have therefore examined whether levels of IGFs (IGF-1 and IGF-11) and IGFBPs (IGFBP-1 and IGFBP-3) differ when insulin is infused into the portal or peripheral vascular system. IGF, IGFBP, and GH levels were determined within 1-3 weeks of diagnosis in 36 patients (ranging in age from 18 to 22 years) with Type 1 diabetes mellitus. IGF-1 levels were low before insulin therapy administration (0.49 +/- 0.05 vs. 1.11 +/- 0.04 U/ml in controls, P < 0.01). With insulin treatment, IGF-1 levels rose to the normal range and IGF-1 normalisation depended on diabetes control and the route of insulin infusion. Diabetic patients with conventional insulin therapy (CIT; n = 12) had low IGF-1 (0.57 +/- 0.07 U/ml) compared with patients with continuous subcutaneous insulin infusion (CSII; n = 12; 0.75 +/- 0.08 U/ml; P < 0.05) and intraportal insulin infusion (IPII; n = 12; 1.07 +/- 10.05 U/ml; P < 0.05). Significant correlations were found between IGF-1 and parameters of glycemic control: HbA1c (r = -0.64; P < 0.01) and glycemia (r = -0.56; P < 0.05). The pattern of changes in IGF-11 levels was not significantly different from that of controls and was not altered by insulin therapy (0.98 +/- 0.08 and 1.01 +/- 0.04 U/ml in controls). Measured fasting 08:00 h IGFBP-1 levels were elevated 3-fold and IGFGP-3 levels were 2-fold lower in diabetic patients than in controls. Elevated IGFBP-1 levels were significantly correlated with metabolic control (glycemia, r = 0.64, P < 0.01; HbA1c, r = 0.71, P < 0.01). The mean elevated GH level before insulin administration (13.4 +/- 0.9 mg/l) was decreased by intensified insulin therapy (CSII, 8.8 +/- 0.6, P < 0.05; IPII, 5.6 +/- 0.9 mg/l, P < 0.001). There was a negative correlation between GH and IGF-1 (r = -0.72, P < 0.01). These results show the role of glycemic control and the route of insulin administration in the normalisation of IGF-1, IGFBP-1 and GH up to non-diabetic controls in patients with recent-onset Type 1 diabetes mellitus.

Comparison of peripheral and portal (via the umbilical vein) routes of insulin infusion in IDDM patients.

Twelve subjects with insulin-dependent diabetes mellitus were treated using continuous subcutaneous insulin infusion (CSII) and intraportal insulin infusion (IPII) via the umbilical vein for 4 mo. Glucose control improved in both CSII and IPII groups, but a decrease in glucose and HbAIc was more rapid and more significant in the IPII group than in CSII, even though insulin requirement was lower during IPII than CSII (40 +/- 2 vs. 50 +/- 2 U/day, P less than 0.05). The insulin plasma fasting levels were different (88 +/- 10.7 in the IPII group vs. 263 +/- 23 pM in CSII, P less than 0.001). High plasma levels of lactate, pyruvate, alanine, cortisol, and growth hormone were decreased in both groups, with their full normalization only in the IPII group. Glucagon concentrations were low in both groups at the beginning of the study (30.0 +/- 4.1 in the CSII group and 32.3 +/- 1.8 ng/L in IPII); they were equalized to control values in the IPII group and were low in the CSII group at the study's end (46.0 +/- 3.7 in IPII vs. 31.7 +/- 3.1 ng/L in CSII, P less than 0.05. We conclude that intraportal administration of insulin via the umbilical vein at rates of 0.01-0.05 U.kg-1.hr-1 reduces plasma levels of glucose, three carbon precursors, cortisol, and growth hormone by a direct action on the liver, and the hepatic action of peripherally administered insulin is manifested only when the infusion rate is increased to 0.1-0.3 U.kg-1.hr-1.(ABSTRACT TRUNCATED AT 250 WORDS)