Biomedical subjects

A Caumo

Publications and source records attributed to A Caumo.

57 records · Page 4Linked to original sources

PubMed1993

Peritoneal and subcutaneous absorption of insulin in type I diabetic subjects.

We and others have shown that in type I diabetes, ip insulin delivery results in lower free insulin levels than sc delivery. The aim of this study was to compare the rate of appearance of insulin in the peripheral circulation during ip and sc insulin administration in type I diabetes, in steady state and nonsteady state. To do this, we determined free insulin levels during ip or sc infusion as well as the impulse response of the insulin system after iv injection of a 6-nmol bolus of insulin. Twelve hours after a constant basal insulin infusion (5.5 +/- 1.4 nmol/h) was started, five C-peptide-negative type I diabetic subjects showed a lower systemic rate of appearance of insulin (expressed as a percentage of the administered dose) with ip than sc administration (27 +/- 6% vs. 40 +/- 10%; P < 0.001). In nonsteady state, when the infusion rate was increased from basal to 15 nmol/h (0-150 min) and subsequently to 42 nmol/h (150-300 min), the percent increase in insulin's systemic rate of appearance was higher with ip than sc infusion (P < 0.05 from 60-150 min; P < 0.01 from 150-300 min), indicating faster absorption. Thus, we conclude that insulin is more rapidly absorbed from the peritoneal cavity than from sc tissue. However, with ip administration, a sizable amount of insulin, once absorbed, is extracted before reaching the peripheral circulation, most likely by the liver. This is indirect evidence that ip insulin delivery results in a portal-peripheral insulin gradient in humans.

Adult↗

PubMed1992

Intravenous infusion of diarginylinsulin, an insulin analogue: effects on glucose turnover and lipid levels in insulin-treated type II diabetic patients.

Diarginylinsulin is an intermediate in the conversion of proinsulin to insulin and is usually present in small amounts in vivo in humans. This study was designed to evaluate the following in insulin-treated type II diabetic patients: (1) the feasibility of an overnight intravenous infusion of diarginylinsulin, as compared with an overnight intravenous infusion of short-acting insulin, and the degree of early morning glycemic control; and (2) the effects of diarginylinsulin and human insulin on hepatic glucose production (HGO) in the postabsorptive state and on the glucose turnover rate and peripheral insulin sensitivity during an euglycemic hyperinsulinemic clamp. Diarginylinsulin and regular human insulin maintained a comparable degree of normoglycemia during the night, without significant glucose increases in the morning. Free-diarginylinsulin and free-insulin concentrations were not significantly different, and (HGO) was 2.1 +/- 0.5 versus 2.1 +/- 0.4 mg/kg/min with diarginylinsulin and regular human insulin, respectively (NS). During the euglycemic clamp, glucose infusion rate per unit of diarginylinsulin or human insulin infused (M/I ratio) was similar, and HGO was equally suppressed with diarginylinsulin and regular human insulin. No significant differences were seen in NEFA and triglyceride levels. In conclusion, these results indicate that diarginylinsulin is as potent as regular human insulin; it is normalizes HGO in the postabsorptive state; and its hepatic and peripheral actions on glucose and lipids are comparable to those of human insulin during an euglycemic hyperinsulinemic clamp.

Circadian Rhythm↗

PubMed1991

Minimal models of glucose disappearance: lessons from the labelled IVGTT.

In this paper the domain of validity of the unlabelled and labelled minimal models of glucose disappearance is studied. Labelled intravenous glucose tolerance tests were performed in six normal subjects using 3-3H-glucose as the tracer. Insulin and unlabelled glucose data were analysed with the minimal model of glucose disappearance. The model provides estimates of glucose effectiveness (SG) and insulin sensitivity (SI) which measure the effects of glucose per se and insulin on both glucose production and disposal. Insulin and labelled glucose data were analysed with the labelled minimal model of tracer disappearance. Estimates of glucose effectiveness (SG*) and insulin sensitivity (SI*) which reflect disposal processes only were calculated. The results of the two minimal models suggest two areas of model error. Firstly, the relationships between labelled and unlabelled parameters contradict the theoretical expectation. Secondly, the time-course of hepatic glucose production is unrealistic. Possible sources of these inconsistencies are an inadequate description of the glucose and/or insulin effect upon hepatic glucose production, and the assumption that glucose kinetics are monocompartmental. The monocompartmental description of glucose kinetics may affect both model parameters and hepatic glucose production and this leads to a critical reexamination of the previously published validation studies in which the minimal model metabolic indices have been compared with the analogous indices measured during glucose clamp studies.

Adult↗