Plasma Immunoreactive Insulin Concentrations Research Articles

202: The association between maternal insulin resistance in mid pregnancy and neonatal birth weight in uncomplicated pregnancies

resistance in mid pregnancy and neonatal birth weight in uncomplicated pregnancies Hiroshi Yamashita, Masashi Fukuda, Yukari Kugishima, Yuki Yamauchi, Akiko Kuzume, Takashi Hashimoto, So Sugimi, Naoko Yatsunami, Sachie Suga, Nobuko Kusuda, Ichiro Yasuhi Nagasaki Medical Center, Obstetrics and Gynecology, Omura-city, Japan OBJECTIVE: The purpose of this study was to determine whether maternal insulin resistance measured by homeostasis model assessmentinsulin resistance (HOMA-IR) in mid pregnancy is associated with neonatal birth weight in uncomplicated pregnancies. STUDY DESIGN: We included singleton pregnant women who had a 75g oral glucose tolerance test (OGTT) during mid pregnancy because of a positive gestational diabetes (GDM) screen. We measured HOMA-IR derived from fasting plasma glucose and immuno-reactive insulin concentration at OGTT. Women with GDM, hypertension, or fetal malformation were excluded. Using multiple and logistic regression analysis to adjust for confounding variables including maternal age, prepregnancy body mass index (BMI), plasma glucose levels at OGTT, and gestational age (GA) at delivery, we tested the relation of mid pregnancy maternal HOMA-IR to neonatal birth weight and large for GA (LGA) infants. RESULTS: We included 557 Japanese pregnant women. The mean maternal age, prepregnancy BMI, GA at OGTT, and HOMA-IR, GA at delivery, and birth weight were 31.8 / 5.0 years, 22.0 / 3.7 kg/ m2, 30.5 / 4.0 weeks, and 1.46 / 0.8, 39.0 / 1.7 weeks, and 3,030 / 470 g, respectively. HOMA-IR was positively associated with birth weight after controlling confounding variables (p .05). Higher HOMA-IR was significantly associated with an increased incidence of LGA infants (n 38) with the adjusted odds ratio of 1.71 per one unit of HOMA-IR (95% confidence interval, 1.11-2.66). CONCLUSION: Our findings suggest that the degree of maternal insulin resistance measured by HOMA-IR during mid pregnancy is associated with birth weight in uncomplicated pregnancies. Mid pregnancy HOMA-IR could be a predictor of fetal overgrowth, independent of maternal glucose levels and obesity.

Glucose tolerance in amyotrophic lateral sclerosis.

Blood glucose and plasma insulin during an oral glucose tolerance test were determined in 21 patients with amyotrophic lateral sclerosis and in 10 control patients matched for age, obesity and physical activity. In addition, 125I-insulin binding to circulating erythrocytes were studied in a subgroup of 4 ALS patients and 8 controls. Both impaired glucose tolerance and diabetes mellitus were evenly distributed between the study groups, and no difference in mean blood glucose levels during the OGTT was found between ALS and control patients. Fasting plasma immunoreactive insulin concentration was significantly higher in ALS patients as compared to controls, but plasma IRI increments to the glycemic stimulus were similar in the 2 groups. The number of insulin binding sites per cell appeared lower in patients with ALS, but the difference in receptor concentration was not statistically significant. In addition, the specific bound fraction of 125I-insulin showed no difference between ALS and control patients. In conclusion, we were unable to demonstrate any marked deterioration of glucose tolerance or increase in insulin resistance in patients with ALS.

Clinical evaluation of plasma insulin and C-peptide levels with 3 different high-flux dialyzers in diabetic patients on hemodialysis

Changes in plasma immunoreactive insulin (IRI) and connecting-peptide immunoreactivity (CPR) concentrations during hemodialysis (HD) were evaluated in diabetic HD patients with 3 different high-flux membranes. The removal properties of the membranes were compared. In this prospective controlled study, 15 stable diabetic patients on HD were randomly selected for 6 HD sessions with 3 different membranes: polysulfone (PS), cellulose triacetate (CTA), and polymethylmethacrylate (PMMA). Blood samples were obtained from the blood tubing at the arterial (A) site at the beginning and end of the sixth HD session. At 60 minutes after dialysis initiation, blood samples were obtained from both the A and venous (V) sites of the dialyzer to investigate the clearance and removal properties of the membranes. The plasma IRI and CPR levels decreased significantly at each time point with all 3 membranes. IRI clearance with the PS membrane was significantly higher than that with the CTA and PMMA membranes. No difference was observed in the IRI reduction rate between the 3 membranes. CPR clearance and reduction rate with the PMMA membrane were lower than with the PS and CTA membranes. No significant difference was observed in serum creatinine clearance and reduction rates between the 3 membranes; however, serum urea nitrogen clearance was significantly lower with the PMMA membrane compared with the PS and CTA membranes. A significantly high beta2-microglobulin clearance and reduction rate was achieved in the order PS > CTA > PMMA. Plasma IRI and CPR are cleared by HD; their clearance rates differ with the dialyzer membranes. Plasma IRI clearance with the PS membrane is higher than that with the CTA and PMMA membranes.

Daily blood glucose profiles of glibenclamide and gliclazide taken once or twice daily in elderly type 2 diabetic patients

The aim of this study was to evaluate the difference in daily blood glucose profiles between once- and twice-daily regimens of a moderate daily dose of glibenclamide or gliclazide in elderly patients with type 2 diabetes. Daily blood glucose profile data were evaluated in 18 elderly type 2 diabetic patients treated with 80 mg/day gliclazide or 5 mg/day glibenclamide as monotherapy. The first daily blood glucose profile of the twice-daily regimen was performed approximately 1 week before hospital discharge, and the second was performed after taking a once-daily regimen for 4-7 days. Plasma glucose and plasma immunoreactive insulin (IRI) concentrations were measured daily at 12 time points: 08.00 (before breakfast); 10.00; 12.00 (before lunch); 14.00; 18.00 (before dinner); 20.00; 0.00; 02.00; 03.00; 04.00; 06.00; and 08.00 hours the next morning. Daily blood glucose profiles and plasma IRI profiles did not differ between the once- and twice-daily regimen groups in either the gliclazide group or the glibenclamide group. Plasma glucose values between midnight and early morning tended to be lower than the 08.00 hours plasma glucose value in the glibenclamide group, but not in the gliclazide group. These results suggest that the blood glucose-lowering effects of a once- and twice-daily moderate daily dose of glibenclamide or gliclazide do not differ in elderly type 2 diabetic patients. However, glibenclamide, regardless of the dosage schedule, tends to lower the plasma glucose values between midnight and early morning.

Fulminant type 1 diabetes mellitus observed in insulin receptor substrate 2 deficient mice

The objective of this study was to characterise the fulminant type 1 diabetes mellitus (DM) accompanying abrupt hyperglycaemia and ketonuria observed in insulin receptor substrate 2 (IRS2)-deficient mice. IRS2-deficient mice backcrossed onto the original C57BL/6J:Jc1 background (B6J-IRS2(-/-) mice) for more than 10 generations were used. Eight male IRS2-deficient mice with ketonuria and abrupt increase in plasma glucose concentrations over 25 mmol/l were used as the fulminant type 1 diabetic mice (diabetic mice) and 8 male IRS2-deficient mice (8 weeks old) without glycosuria were used as the control mice. Plasma metabolite, immunoreactive insulin (IRI) and C-peptide concentrations, hepatic energy metabolism related enzyme activities and histopathological change in pancreatic islets were investigated. The diabetic mice showed significantly higher plasma glucose and cholesterol concentrations and lower plasma IRI and C-peptide concentrations than the control mice. In livers of the diabetic mice, glycolytic and malate-aspartate shuttle enzyme activities decreased significantly and gluconeogenic, lipogenic and ketone body synthesis enzyme activities increased significantly compared to those in the control mice. The pancreatic islets of the diabetic mice decreased significantly in size and number of beta cells. The diabetic IRS2-deficient mice did not show the islet-related antibodies observed in the diabetic NOD mice in their sera. The characteristics of the diabetic IRS2-deficient mice resembled those of the human nonautoimmune fulminant type 1 DM. IRS2-deficient mice may be a useful animal model for studying the degradation mechanism of pancreatic beta cells in the process of development of fulminant type 1 DM.

The influence of hemodialysis membranes on the plasma insulin level of diabetic patients on maintenance hemodialysis

The aim of the present study was to evaluate the alteration in plasma immunoreactive insulin (IRI) concentrations due to hemodialysis (HD) treatment by using three types of membranes in diabetic HD patients. We recruited 20 outpatients on maintenance HD with diabetes for this crossover study. HD was performed using membranes made of cellulose triacetate (CTA), polyester-polymer alloy (PEPA), and polysulphone (PS). These membranes were used for 2 weeks (6 HD sessions) in each patient in a randomized order decided by drawing lots. Blood samples were obtained at the beginning and end of the HD session from the blood tubing at the arterial (A) site. At 60 min after the initiation of dialysis, blood samples were obtained from the blood tubing at both the A and venous (V) sites of the dialyzer. The plasma IRI levels decreased significantly at the sites an hour after initiating HD in all membranes. The clearance of IRI was significantly higher in the case of the PS membrane when compared with the CTA and PEPA membranes. It was concluded that plasma insulin is cleared by HD, and the rate differs for each membrane. Plasma insulin clearance with the PS membrane is higher than that with the PEPA and CTA membranes.

Plasma metabolite concentrations and hepatic enzyme activities in pregnant Romney ewes with restricted feeding

Plasma metabolite concentrations and activities of enzymes related to energy metabolism in plasma, peripheral leukocytes and liver of pregnant Romney ewes with restricted feeding were measured to assess those metabolites and enzymes as indicators for evaluating metabolic conditions in the ewes. The body weights and plasma lactate concentrations of the low-feeding ewes (about 1.0 times maintenance) were significantly lower than those of the high-feeding ewes (about 1.5 times maintenance). There were no significant differences in plasma protein, glucose, triglyceride, cholesterol, pyruvate and immunoreactive insulin concentrations and plasma and leukocyte enzyme activities between both groups. Hepatic malate dehydrogenase activities were significantly higher and hexokinase activities were significantly lower in the low-feeding ewes than in the high-feeding ewes. Restricted feeding could maintain pregnancy and some plasma metabolites and peripheral leukocyte enzymes may be useful indicators for evaluating metabolic changes in ewes.

Changes in metabolite, energy metabolism related enzyme activities and peripheral blood mononuclear cell (PBMC) Populations in beef heifers with two differing liveweight change profiles in New Zealand

Metabolite and immunoreactive insulin (IRI) concentrations, energy metabolism related enzymes activities and peripheral blood mononuclear cell (PBMC) populations were measured in blood of pregnant Angus heifers with differing liveweight change profiles (gaining or losing), in New Zealand to investigate the meanings of those parameters in the restricted feeding beef heifers. Beef heifers losing liveweight (-412 g/day) showed significantly lower concentrations of plasma IRI, and higher concentrations of plasma free fatty acid (FFA) than heifers gaining liveweight (483 g/day). The cytosolic and mitochondrial malate dehydrogenase (MDH) activities and MDH/lactate dehydrogenase (M/L) ratio in leukocytes of the liveweight losing heifers were significantly higher than those the liveweight gaining heifers. Percentages of cluster of differentiation (CD) 3 positive cells and natural killer (NK) cells in PBMC decreased significantly in the liveweight losing heifers compared to those in the liveweight gaining heifers. Plasma IRI and FFA concentrations, leukocyte cytosolic and mitochondrial MDH activities and CD3 positive and NK cell populations may be useful markers to evaluate metabolic conditions and immunity in the restricted feeding beef heifers.

Comparison of Plasma Metabolite Concentrations and Enzyme Activities in Beef Cattle Raised by Different Feeding Systems in Korea, Japan and New Zealand

Concentrations of metabolites and immunoreactive insulin (IRI) and activities of enzymes related to energy metabolism were measured in plasma of Korean and Japanese beef cattle, which were raised by the indoor feeding system programmed to feed larger amount of roughage in their growing periods and larger amount of concentrate diet in their finishing periods (Japanese feeding system), and grazing New Zealand beef cattle. By the Japanese beef grading system, Korean and Japanese beef cattle showed high beef quality score, average grade 3.3 and 3.6, respectively. The plasma free fatty acid and lactate concentrations and lactate dehydrogenase (LDH), malate dehydrogenase (MDH) and aspartate aminotransferase (AST) activities in Korean beef cattle were significantly higher than those in Japanese beef cattle. The plasma lactate concentration in Korean beef cattle was 8.40 mmol/l, which was similar to the values observed in lactic acidosis. The higher activities of plasma LDH, MDH and AST may indicate slight liver damage by slightly acidotic conditions in Korean beef cattle. New Zealand beef cattle fed on pasture which they harvest by grazing showed significantly lower plasma glucose, cholesterol, lactate and IRI concentrations and enzyme activities than those in Korean and Japanese beef cattle fed on larger amount of concentrate diets. Plasma metabolite concentrations and energy metabolism-related enzyme activities may be good indicators for evaluating metabolic conditions of beef cattle raised by different feeding systems.

Plasma Insulin is Removed by Hemodialysis: Evaluation of the Relation Between Plasma Insulin and Glucose by Using a Dialysate With or Without Glucose

The aim of the present study was to evaluate the alteration in plasma immunoreactive insulin (IRI) and glucose concentrations due to hemodialysis (HD) treatment by using a dialysate with or without glucose in HD patients. We divided the patients into three groups: non-diabetic patients (n-DM group), well-controlled diabetic patients (HbA(1c) <7.0% [w-DM group]), and poorly-controlled diabetic patients (HbA(1c) > or = 7.0% [p-DM group]). Using a dialysate with a glucose concentration of 100 mg/dL (glu(+)-dialysate) and a glucose-free dialysate (glu(-)-dialysate), we studied the daily profiles of plasma glucose in the three groups. We measured the levels of plasma glucose and IRI at three time points (predialysis and 2 h and 4 h after the initiation of dialysis) at pre(A) and postdialyzer (V) sites in HD patients. There was a significant increase in the daily profiles of the plasma glucose level from the time before dinner until bedtime in both the w-DM and p-DM groups, when comparing the values on an HD day with those on a non-HD day. In the p-DM group, the use of the glu(-)-dialysate resulted in a significant hyperglycemia in the evening hours when compared with the use of the glu(+)-dialysate. In the DM group, the use of the glu(+)-dialysate resulted in a significant decrease in the plasma glucose and IRI levels during HD. However, in the n-DM group, there was no difference in the plasma glucose levels during HD. On the other hand, the use of a glucose-free dialysate led to a significant decrease in the plasma glucose and IRI levels during HD in all groups. The plasma IRI levels decreased significantly between the A and V sites at each point in all groups irrespective of the glucose concentration of the dialysate. The present study confirmed that the concentration of not only glucose but also IRI had decreased during the passage of the plasma through the dialyzer. In HD patients with diabetes, the glucose content of the hemodialysis solution plays an important role in preventing acute hypoglycemia and hyperglycemia on HD days.

Changes in peripheral leukocytes enzymes activity and plasma metabolite concentrations in growing Holstein calves

Plasma metabolite and immunoreactive insulin concentrations and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in growing Holstein calves. A ratio of girth of abdomen divided by girth of thorax (A/T ratio) of calves was significantly elevated after weaning, and the A/T ratio maybe a good indicator to evaluate rumen development. Plasma glucose and free fatty acid concentrations were changed in calves accompanying change in feeding. Activities of lactate dehydrogenase with pyruvate as substrate (LDH-P) and hexokinase (HK) in cytosolic fractions of peripheral leukocytes decreased significantly after weaning the calves reflecting the change of energy source from milk replacer with high percentages of fat and glucose and lactose as absorbable carbohydrate to pelleted feed containing starch as less absorbable carbohydrate and roughage. Some peripheral leukocyte enzymes such as LDH and HK may be good indicators to evaluate changes in energy metabolism of growing calves.

Comparison of Expression of Glucokinase Gene and Activities of Enzymes Related to Glucose Metabolism in Livers between Dog and Cat

Plasma glucose and immunoreactive insulin (IRI) concentrations and activities of enzymes related to glucose metabolism in livers were measured in dogs and cats. Nucleotide sequences of the conserved region of glucokinase (GK) cDNA that contained ATP- and glucose-binding domains were determined in canine liver and feline pancreas for design of the species-specific oligonucleotide primers for reverse transcription-polymerase chain reaction (RT-PCR) analysis. There were no significant differences in plasma glucose and IRI concentrations between dogs and cats. In feline liver, although GK activities were not detected, activities of hexokinase, fructokinase, pyruvate kinase, glucose-6-phosphate dehydrogenase, fructose-1,6-bisphosphatase and glucose-6-phosphatase were significantly higher than those in canine liver. The partial sequences of canine liver GK and feline pancreas GK cDNA were respectively 88% and 89% identical with the rat liver GK cDNA. Expression of GK gene was observed in canine liver and pancreas and feline pancreas with RT-PCR using species specific primers based on the cDNA sequences.

Changes in Activities of Enzymes Related to Energy Metabolism in Peripheral Leukocytes of Fattening Steers

Glucose, triglyceride, cholesterol and immunoreactive insulin (IRI) concentrations, some enzyme activities in plasma, and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in fattening Japanese Black Wagyu x Holstein steers fed on different diets at 8, 12, 16, 20 and 24 months of age. The plasma IRI concentrations at 20 and 24 months of age were significantly higher than those at 8 months of age. Activities of hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PD), aspartate aminotransferase (AST), and malate dehydrogenase (MDH) in cytosolic fractions, and glutamate dehydrogenase (GLDH), MDH and AST in mitochondrial fractions in peripheral leukocytes of steers at 24 months of age were significantly higher than those at 8 months. Increasing plasma insulin concentration was considered to induce acceleration of glucose utilization in leukocytes of fattening steers. The cytosolic ratio of MDH/lactate dehydrogenase (LDH) activity in leukocytes increased significantly in the fattening process and was considered to be a useful indicator for evaluating changes in energy metabolism in steers.

Activities of enzymes in some types of peripheral leucocytes may reflect the differences in nutrient metabolism between dogs and cats

Plasma metabolites and immunoreactive insulin (IRI) concentrations and enzyme activities of some types of peripheral leucocytes were measured to clarify one aspect of the differences in nutrient metabolism between dogs and cats. There were no significant differences in plasma concentrations of glucose, triglyceride, free fatty acids and IRI between dogs and cats. Higher total cholesterol and lower HDL cholesterol concentrations were observed in feline plasma, and H/T ratio (HDL/total cholesterol concentrations) was significantly lower than that in canine plasma. The cytosolic activities of fructokinase (FK), pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6PD) and lactate dehydrogenase (LDH) were significantly higher and the activities of cytosolic malate dehydrogenase (MDH) and mitochondrial glutamate dehydrogenase (GLDH) were significantly lower in feline leucocytes than those in canine leucocytes. Higher activities of FK, PK and G6PD, which regulate the rate of biosynthesis of fatty acids, may reflect the different characteristics in nutrient metabolism in feline tissues from canine tissues.

Hyperproinsulinaemia in elderly subjects: evidence for age-related pancreatic β-cell dysfunction

We investigated whether pancreatic beta-cell dysfunction has a role in the pathogenesis of glucose intolerance in the elderly by comparing plasma glucose, immunoreactive insulin, C-peptide and proinsulin concentrations during a 100-g oral glucose load in six healthy older male volunteers [aged 69 (65.9-74.9) years; median (95% confidence limits)] and seven young male controls [aged 24.0 (21.9-26.3) years]. Fasting and integrated concentrations of glucose and C-peptide were similar in the elderly and young. Although fasting, insulin and proinsulin levels were similar, integrated insulin (P=0.05) and proinsulin (P<0.05) concentrations were higher in the elderly than in controls. Insulin resistance, measured as homeostasis model assessment, was greater (P<0.05) in the elderly than in controls. Elderly men had greater molar ratios of integrated insulin:C-peptide (P<0.05) and proinsulin:C-peptide (P<0.01) but their respective fasting molar ratios were similar when compared with controls. Pancreatic beta-cell secretion in older subjects, as assessed by C-peptide concentrations, was inappropriately low in the presence of insulin resistance. Their post-prandial 'hyperinsulinaemia' is probably due to a combination of hyperproinsulinaemia and reduced metabolic clearance of insulin. Older subjects had disproportionately high proinsulin to C-peptide levels, suggesting pancreatic beta-cell dysfunction. These results are consistent with the notion that decreased insulin sensitivity and pancreatic beta-cell dysfunction may predispose the elderly to glucose intolerance.

Cardiovascular disease and risk factors in adults with hypopituitarism.

In 1992, Cuneo et al. (1992) reviewed, in this journal, the consequences of growth (GH) deficiency during adult life and coined the term ‘Growth hormone deficiency (GHD) syndrome in adults’. Limited information was available then on cardiovascular disease and risk factors in adults with hypopituitarism. More data have been published since on cardiovascular morbidity in symptom-free hypopituitary adults. Several groups have also published results on the effects of GH therapy on cardiac structure and function and on the cardiovascular risk factors. We shall review here the epidemiological and experimental data on cardiovascular morbidity and mortality in adult hypopituitarism. We shall also examine the prevalence of cardiovascular risk factors in this group of patients and their potential causes focusing on the possible role of GH deficiency and the effects of GH replacement.

Ovarian hormone-induced beta-cell hypertrophy contributes to the homeostatic control of beta-cell mass in OLETF female rat, a model of Type II diabetes.

A sexual dimorphism regarding the incidence of diabetes mellitus in OLETF rat, a model of Type II diabetes, has been reported. As a result, the effects of ovarian hormones on beta cells per se was examined by comparing the capacity of beta-cell proliferation and changes in blood glucose and plasma insulin concentrations after a 70% pancreatectomy. All female animals were randomly assigned to two protocols. The rats involved in protocol I received either a 70% pancreatectomy (Px) or a sham pancreatectomy (sham) at 6 weeks of age, along with their diabetes-resistant counterparts, female LETO rats, which served as normal controls. The rats belonging to protocol II were given an ovariectomy (Ox) at 5 weeks of age, and one week later, they were subjected to either Px or the sham operation, with/without hormone (estradiol, 50 microg/kg; testosterone, 1 mg/kg) replacement. The findings indicate that the capacity for compensatory growth of beta cells after Px was affected by both sex hormonal and genetic components, since a 70% Px resulted in sustained hyperglycaemia within the first week after surgery, but was ameliorated by an increase in beta-cell mass thereafter in the non-Ox Px OLETF rats. The Ox also caused a decline in beta-cell mass which could be improved by replacement with ovarian hormones. Not only endogenous but also replacement ovarian hormones, led to a beneficial effect on beta cells per se in OLETF female rats. This was reflected by an increased beta-cell mass accompanied by a parallel increase in plasma immunoreactive insulin concentration. The effects of ovarian hormones, however, contributed to the beta-cell hypertrophy rather than expansion of the beta-cell population to achieve glucose homeostasis, as evidenced by an increased area of individual beta-cell after Px rather than an increased BrdU-labelling index for the beta cells. The present study suggests that ovarian hormone-induced beta-cell hypertrophy may typically occur, to compensate for changes in functional demand as the results of a 70% Px in female OLETF rats.

Modulation of apolipoprotein gene expression in fatty liver of obese rats: enhanced APOA-IV, but no APOB expression by a high sucrose diet.

Hepatic lipoprotein production is important to the understanding of mechanisms involved in the development of fatty liver and hyperlipidemia. Previously, we have reported that hepatic fatty acid synthesis and apolipoproteinB transcription are increased in obese rats. Here, we describe the effects of a high sucrose diet on hepatic fatty acid synthesis and apolipoprotein gene expression in obese rats. Obese rats with ventromedial hypothalamic lesions were fed on a high sucrose diet (30.3% of cal) or lab chow for 11 weeks. Serum triglycerides and plasma immuno-reactive insulin concentrations were further increased in the obese rats fed a high sucrose diet. The experimental diet increased the activity of hepatic acetyl-CoA carboxylase, the rate limiting enzyme for hepatic fatty acid synthesis, and triglycerides content, concurrent with an increase abundance of apolipoproteinA-IC mRNA in the obese rats. Despite further accumulation of hepatic triglycerides there was no further increase in hepatic apolipoproteinB mRNA abundance in the obese rats fed the high sucrose diet. These data suggest that the synthesis of hepatic fatty acids but not of apolipoproteinB is further increased in obese rats fed the high sucrose diet, and that apolipoproteinA-IV gene expression may be modulated in response to alterations in hepatic triglycerides flux.

Modified method using a somatostatin analogue, octreotide acetate (Sandostatin) to assess in vivo insulin sensitivity.

In order to evaluate the steady state plasma glucose (SSPG) method by using a new somatostatin derivative, octreotide acetate (Sandostatin) instead of somatostatin that we had used for the insulin sensitivity test, we examined whether octreotide was able to suppress C-peptide (CPR), glucagon (IRG), and GH to a similar degree to that achieved with somatostatin. A total of 52 studies were performed in 45 essential hypertensive subjects and 7 healthy subjects. Octreotide was given subcutaneously in a does of 50 micrograms or 100 micrograms 10 min before the test (sc 50, sc 100 groups) or intravenously infused over 2 h (10 micrograms in bolus followed by a constant infusion, 50, 100, or 150 micrograms/2 h: i.v. 50, i.v. 100, i.v. 150 groups). In all of the groups the plasma immunoreactive insulin (IRI) concentration increased gradually after insulin injection and reached the steady state plasma insulin (SSPI) level between 40 and 60 microU/ml at 60 min through 120 min. Plasma CPR at 120 min was the most suppressed (by 67% of the basal level in i.v. 150 group during the study period), but on the other hand in both the sc 100 and i.v. 100 groups the plasma CPR concentration at 120 min was suppressed by nearly 40%, but not significantly suppressed in either the sc 50 or the i.v. 50 group. Plasma IRG and GH were strongly suppressed after 60 min in all groups during the study period. Plasma glucose had increased significantly at 30 min and reached the steady state at 90 min through 120 min in hypertensive and healthy subjects. The results indicated that the modified SSPG method with continuous intravenous infusion of Octreotide at 150 micrograms/2 h was adequate for the measurement of insulin sensitivity.

Effect of addition of hyaluronic acid to highly concentrated insulin on absorption from the conjunctiva in conscious diabetic dogs.

Insulin absorption from the conjunctiva was investigated in five pancreatectomized diabetic mongrel dogs, with the nasolacrimal ducts occluded by micro plugs to prevent insulin absorption from nasolacrimal membrane. In the anaesthetized state, highly concentrated porcine insulin (1000 units mL-1, pH 7.4) was absorbed rapidly and significantly from the conjunctiva. Plasma immunoreactive insulin concentrations increased significantly up to 3 h after insulin administration to conjunctival membranes. Plasma glucose concentration decreased significantly compared with saline control experiments after insulin administration (10 units kg-1) at 3 h (8.3 +/- 0.1 vs 15.6 +/- 0.6 mmol, P < 0.01). However, in the conscious state, there was no significant increase in the plasma insulin levels after topical insulin administration. To improve insulin absorption in the conscious state, we examined the effect of increasing viscosity of insulin preparation with hyaluronic acid. In anaesthetized experiments, there were no significant changes in the bioavailability of insulin after addition of hyaluronate (0.84 +/- 0.11 vs 0.87 +/- 0.05%). In the conscious state, with addition of hyaluronic acid, the area under the curve of plasma insulin concentration was significantly increased (1842 +/- 383 vs 75 +/- 24 m units min L-1, P < 0.01). The bioavailability of insulin absorption was significantly increased after addition of hyaluronate (0.68 +/- 0.14 vs 0.03 +/- 0.01%, P < 0.01). From this study we could demonstrate that the conjunctiva is a potential route for insulin administration, and increased viscosity by the addition of hyaluronate was found effective in increasing the bioavailability of insulin absorption from conjunctival membrane in the conscious state.