Randomized comparison of metabolic control achieved by intraperitoneal insulin infusion with implantable pumps versus intensive subcutaneous insulin therapy in type I diabetic patients.

OBJECTIVE: To compare intraperitoneal implantable insulin infusion (IP) to subcutaneous (SC) intensive insulin therapy. RESEARCH DESIGN AND METHODS: Twenty-one insulin-dependent (type I) diabetic patients aged 24-61 yr underwent a 3-mo treatment optimization using multiple SC daily injections or external pumps. Patients were then randomized (time 0 mo) to IP infusion using Infusaid-programmable pumps or continuation on SC intensive insulin for 6 mo. RESULTS: No differences were noted between study and control group data. However, longitudinal within-group comparisons from baseline showed that glycosylated hemoglobin improved to near-normal in both groups: IP, 9.0 +/- 0.5 vs. 7.8 +/- 0.6% (P less than 0.05) and SC, 8.4 +/- 0.5 vs. 7.5 +/- 0.3% (P less than 0.5) at 0 and 4 mo, respectively (normal less than 6.9%). The percentage of blood glucose tests greater than 11 mM at 0 and 6 mo was 28 +/- 5 vs. 16 +/- 4% in the IP group (P less than 0.05) and 22 +/- 5 vs. 24 +/- 7% in the SC group (NS). At 0 and 6 mo, the standard deviation of blood glucose values, an index of glycemic fluctuations, was 4.3 +/- 0.4 vs. 3.2 +/- 0.5 mM in the IP group (P less than 0.05) and 3.7 +/- 0.3 vs. 4.0 +/- 0.4 mM in the SC group (NS). Weight, insulin dosages, circulating lipid levels, and the frequency of severe hypoglycemic reactions and biochemical hypoglycemias were similar and did not change in the two groups. CONCLUSIONS: IP-implantable pumps compared with SC intensive insulin therapy have similar effects on most metabolic variables and are equally effective at achieving near-normal glycemic levels. Only longitudinal data suggest that IP treatment may be more effective at limiting glycemic fluctuations.

Determination of portal insulin absorption from peritoneum via novel nonisotopic method.

The absorption mechanism of insulin administered in the peritoneal cavity (IP) is of current interest because of the near availability of implantable insulin-infusion devices for the treatment of diabetes. To determine the fraction of insulin absorbed by the portal circulation after IP administration, a novel nonisotopic method is described. Conscious fasting diabetic dogs were studied at normoglycemia via the euglycemic insulin-clamp method. Posthepatic appearance of insulin and C-peptide were measured in peripheral blood during IP or intravenous (IV) equimolar infusion of insulin and C-peptide at two sequential 3-h infusion rates of 3.2 and 12.8 pmol.kg-1.min-1. Prior studies have shown that 40-60% of portal insulin is extracted at first pass by the liver, whereas C-peptide is not extracted. Thus, the fraction (F) of IP insulin not taken up by liver at first pass and consequently the fraction absorbed by the portal circulation can be derived from insulin (I) and C-peptide (C) plasma concentration values at steady state with a monocompartmental model where F = (IIP/IIV)(CIV/CIP). The mean +/- SE value of F was 49.7 +/- 8.8%. Glucose disappearance rates were lower with IP than IV infusion but similar when peripheral insulin levels were matched. We conclude that IP insulin is almost entirely absorbed by the portal circulation and induces lower glucose disappearance rates than IV insulin because of lower peripheral circulating insulin levels. Whether these properties make the IP route a more appropriate route for insulin therapy than the subcutaneous or IV routes remains to be established.