The effect of acute dual SGLT1/SGLT2 inhibition on incretin release and glucose metabolism after gastric bypass surgery

Enhanced meal-related enteroendocrine secretion, particularly of glucagon-like peptide-1 (GLP-1), contributes to weight-loss and improved glycemia after Roux-en-Y gastric bypass (RYGB). Dietary glucose drives GLP-1 and glucose-dependent insulinotropic polypeptide (GIP) secretion postoperatively. Understanding how glucose triggers incretin secretion following RYGB could lead to new treatments of diabetes and obesity. In vitro, incretin release depends on glucose absorption via sodium-glucose cotransporter 1 (SGLT1). We investigated the importance of SGLT1/SGLT2 for enteropancreatic hormone concentrations and glucose metabolism after RYGB in a randomized, controlled, crossover study. Ten RYGB-operated patients ingested 50 g of oral glucose with and without acute pretreatment with 600 mg of the SGLT1/SGLT2-inhibitor canagliflozin. Paracetamol and 3-O-methyl-d-glucopyranose (3-OMG) were added to the glucose drink to evaluate rates of intestinal entry and absorption of glucose, respectively. Blood samples were collected for 4 h. The primary outcome was 4-h plasma GLP-1 (incremental area-under the curve, iAUC). Secondary outcomes included glucose, GIP, insulin, and glucagon. Canagliflozin delayed glucose absorption (time-to-peak 3-OMG: 50 vs. 132 min, P < 0.01) but did not reduce iAUC GLP-1 (6,067 vs. 7,273·min·pmol^-1·L^-1, P = 0.23), although peak GLP-1 concentrations were lowered (-28%, P = 0.03). Canagliflozin reduced GIP (iAUC -28%, P = 0.01; peak concentrations -57%, P < 0.01), insulin, and glucose excursions, whereas plasma glucagon (AUC 3,216 vs. 4,160 min·pmol·L^-1, P = 0.02) and amino acids were increased. In conclusion, acute SGLT1/SGLT2-inhibition during glucose ingestion did not reduce 4-h plasma GLP-1 responses in RYGB-patients but attenuated the early rise in GLP-1, GIP, and insulin, whereas late glucagon concentrations were increased. The results suggest that SGLT1-mediated glucose absorption contributes to incretin hormone secretion after RYGB.

Ethnic differences in insulin secretory function between black African and white European men with early type 2 diabetes

AIM

To test the hypothesis that men of black (West) African ethnicity (black African men [BAM]) with early type 2 diabetes (T2D) would have greater insulin secretory deficits compared with white European men (WEM), following prediabetic hypersecretion.

METHODS

In 19 BAM and 15 WEM, matched for age, body mass index and duration of diabetes, we assessed and modelled insulin secretory responses to hyperglycaemia stimulated intravenously (hyperglycaemic clamp) and orally (meal tolerance test).

RESULTS

With similar post-challenge glucose responses, BAM had lower second-phase C-peptide responses to intravenous glucose (BAM 70.6 vs WEM 115.1 nmol/L/min [ratio of geometric mean 0.55, 95% confidence interval {CI} 0.37, 0.83]; P = .006) and to oral glucose (BAM 65.4 vs WEM 88.5 nmol/L/min [mean difference -23.2, 95% CI -40.0, -6.3]; P = .009). Peripheral insulin response in BAM to oral glucose was preserved (BAM 47.4 vs WEM 59.4 nmol/L/min [ratio of geometric mean 0.89, 95% CI 0.59, 1.35]; P = .566), with relative reductions in insulin clearance (BAM 506.2 vs WEM 630.1 mL/m² BSA/min [mean difference -123.9, 95% CI -270.5, 22.6]; P = .095), associated with enhanced incretin responses (gastric inhibitory polypeptide incremental area under the curve: BAM 46.8 vs WEM 33.9 μg/L/min [mean difference 12.9, 95% CI 2.1, 23.7]; P = .021).

CONCLUSIONS

In early T2D, BAM had significantly lower insulin secretory responses to intravenous and oral stimulation than WEM. Lower insulin clearance, potentially driven by increased incretin responses, may act to preserve peripheral insulin concentrations. Tailoring early management strategies to reflect distinct ethnic-specific pathophysiology may improve outcomes in this high-risk population.

Efficacy and safety of canagliflozin as add-on therapy to teneligliptin in Japanese patients with type 2 diabetes mellitus: Results of a 24-week, randomized, double-blind, placebo-controlled trial

AIMS

To investigate efficacy and safety of the sodium-glucose co-transporter 2 (SGLT2) inhibitor canagliflozin administered as add-on therapy to the dipeptidyl peptidase-4 (DPP-4) inhibitor teneligliptin in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

We conducted a multicentre, randomized, double-blind, placebo-controlled, phase 3 clinical trial in Japanese patients with T2DM who had inadequate glycaemic control with teneligliptin. Patients were randomized to receive teneligliptin 20 mg plus either canagliflozin 100 mg (T + C, n = 70) or placebo (T + P, n = 68) once daily. The primary endpoint was the change in glycated haemoglobin (HbA1c) from baseline to week 24. Other endpoints included changes in fasting plasma glucose, body weight, proinsulin/C-peptide ratio, homeostatic model assessment 2-%B and adverse events. Patients also underwent mixed-meal tolerance tests.

RESULTS

The difference between the T + C and T + P groups for HbA1c change from baseline to week 24 was -0.88% (least-squares mean, P < .001). Fasting plasma glucose, body weight and the proinsulin/C-peptide ratio were significantly lower in the T + C group than in the T + P group. Homeostatic model assessment 2-%B improved with T + C compared with T + P. The T + C group exhibited a decrease in the 2-hour postprandial plasma glucose and plasma glucose area under the curve (AUC)_0-2h in a mixed-meal tolerance test. No significant between-group differences were observed for C-peptide AUC_0-2h or glucagon AUC_0-2h after meals. Incidences of adverse events were 60.0% and 47.1% in the T + C and T + P groups, respectively. No hypoglycaemia was observed.

CONCLUSIONS

Canagliflozin administered as add-on therapy to teneligliptin was effective and well tolerated in Japanese T2DM patients.

Neu5Gc and α1-3 GAL Xenoantigen Knockout Does Not Affect Glycemia Homeostasis and Insulin Secretion in Pigs

Xenocell therapy from neonate or adult pig pancreatic islets is one of the most promising alternatives to allograft in type 1 diabetes for addressing organ shortage. In humans, however, natural and elicited antibodies specific for pig xenoantigens, α-(1,3)-galactose (GAL) and N-glycolylneuraminic acid (Neu5Gc), are likely to significantly contribute to xenoislet rejection. We obtained double-knockout (DKO) pigs lacking GAL and Neu5Gc. Because Neu5Gc^-/- mice exhibit glycemic dysregulations and pancreatic β-cell dysfunctions, we evaluated islet function and glucose metabolism regulation in DKO pigs. Isolation of islets from neonate piglets yielded identical islet equivalent quantities to quantities obtained from control wild-type pigs. In contrast to wild-type islets, DKO islets did not induce anti-Neu5Gc antibody when grafted in cytidine monophosphate-N-acetylneuraminic acid hydroxylase KO mice and exhibited in vitro normal insulin secretion stimulated by glucose and theophylline. Adult DKO pancreata showed no histological abnormalities, and immunostaining of insulin and glucagon was similar to that from wild-type pancreata. Blood glucose, insulin, C-peptide, the insulin-to-glucagon ratio, and HOMA-insulin resistance in fasted adult DKO pigs and blood glucose and C-peptide changes after intravenous glucose or insulin administration were similar to wild-type pigs. This first evaluation of glucose homeostasis in DKO pigs for two major xenoantigens paves the way to their use in (pre)clinical studies.

Antiinflammatory and ROS Suppressive Effects of the Addition of Fiber to a High-Fat High-Calorie Meal

BACKGROUND

Fiber intake is associated with a reduction in the occurrence of cardiovascular events and diabetes.

OBJECTIVE

To investigate whether the addition of fiber to a high-fat, high-calorie (HFHC) meal prevents proinflammatory changes induced by the HFHC meal.

DESIGN

Ten normal fasting subjects consumed an HFHC meal with or without an additional 30 g of insoluble dietary fiber on 2 separate visits. Blood samples were collected over 5 hours, and mononuclear cells (MNCs) were isolated.

RESULTS

Fiber addition to the HFHC meal significantly lowered glucose excursion in the first 90 minutes and increased insulin and C-peptide secretion throughout the 5-hour follow-up period compared with the meal alone. The HFHC meal induced increases in lipopolysaccharide (LPS) concentrations, MNC reactive oxygen species generation, and the expression of interleukin (IL)-1β, tumor necrosis factor α (TNF-α), Toll-like receptor (TLR)-4, and CD14. The addition of fiber prevented an increase in LPS and significantly reduced the increases in ROS generation and the expression of IL-1β, TNF-α, TLR-4, and CD14. In addition, the meal increased Suppressor of cytokine signaling (SOCS)-3 and protein tyrosine phosphatase 1B (PTP-1B) messenger RNA and protein levels, which were inhibited when fiber was added.

CONCLUSIONS

The addition of fiber to a proinflammatory HFHC meal had beneficial anti-inflammatory and metabolic effects. Thus, the fiber content of the American Heart Association meal may contribute to its noninflammatory nature. If these actions of dietary fiber are sustained following long-term intake, they may contribute to fiber's known benefits in the prevention of insulin resistance, type 2 diabetes, and atherosclerosis.

Oxytocin Improves β-Cell Responsivity and Glucose Tolerance in Healthy Men

In addition to its pivotal role in psychosocial behavior, the hypothalamic neuropeptide oxytocin contributes to metabolic control by suppressing eating behavior. Its involvement in glucose homeostasis is less clear, although pilot experiments suggest that oxytocin improves glucose homeostasis. We assessed the effect of intranasal oxytocin (24 IU) administered to 29 healthy, fasted male subjects on glucose homeostasis measured by means of an oral glucose tolerance test. Parameters of glucose metabolism were analyzed according to the oral minimal model. Oxytocin attenuated the peak excursion of plasma glucose and augmented the early increases in insulin and C-peptide concentrations in response to the glucose challenge, while slightly blunting insulin and C-peptide peaks. Oral minimal model analyses revealed that oxytocin compared with placebo induced a pronounced increase in β-cell responsivity (PHI_total) that was largely due to an enhanced dynamic response (PHI_d), and a more than twofold improvement in glucose tolerance (disposition index). Adrenocorticotropic hormone (ACTH), cortisol, glucagon, and nonesterified fatty acid (NEFA) concentrations were not or were only marginally affected. These results indicate that oxytocin plays a significant role in the acute regulation of glucose metabolism in healthy humans and render the oxytocin system a potential target of antidiabetic treatment.

The effect of oral and intravenous dextrose on C-peptide secretion in ponies

Managing equine hyperinsulinemia is crucial for preventing laminitis, but our understanding of the mechanisms involved in insulin dysregulation in this species is incomplete. C-peptide is co-secreted with insulin but is resistant to hepatic metabolism and can be used to study insulin dysregulation. This study examined C-peptide secretion in serial blood samples collected after oral and i.v. dextrose (0.75 g/kg) administration to 9 ponies (BCS, 7.1 ± 0.5). The ponies were designated as hyperinsulinemic (HI) or normoinsulinemic (NI) responders before the study, using oral glucose tests and fasted glucose-to-insulin ratios, and responses were compared between the 2 groups. C-peptide concentrations increased ( < 0.01) rapidly from fasted levels after both oral and i.v. dextrose, with similar area under the concentration-time curve (AUC) for both tests and a significant correlation with AUC. The AUC was similar in HI and NI ponies after i.v. dextrose, indicating similar pancreatic capacity for both groups. However, for oral dextrose, the AUC and the AUC were markedly higher ( < 0.05) in the HI ponies, indicating a greater secretion rate of these peptides. Slower insulin clearance might have also contributed to the larger AUC in HI ponies, but this hypothesis requires further investigation with specific measures of hepatic insulin clearance.

Safety, efficacy and weight effect of two 11β-HSD1 inhibitors in metformin-treated patients with type 2 diabetes

AIMS

We assessed safety and efficacy of two selective 11β-HSD1 inhibitors (RO5093151/RO-151 and RO5027383/RO-838) in this randomized, controlled study in metformin-treated patients with type 2 diabetes.

METHODS

Patients either received placebo (N = 21), RO-151 BID 5 mg (N = 24) or 200 mg (N = 20) or RO-838 QD 50 mg (N = 21) or 200 mg (N = 24) for 28 days. Metabolic assessments comprising of nine-point plasma glucose profiles, oral glucose tolerance tests and determination of metabolic biomarkers including insulin, C-peptide, glucagon, HbA1c and lipids were done at baseline and end of treatment.

RESULTS

Despite the short treatment duration, both RO-151 and RO-838 showed trends for improved HbA1c and consistent reductions in body weight (-0.86 to -1.67 kg) exceeding those observed with placebo (-0.28 kg, p = 0.019 for 200 mg RO-151 vs. placebo). Insulin sensitivity parameters (e.g. HOMA-IR and Matsuda-Index) improved non-significantly with 200 mg RO-151. Lipid parameters did not consistently improve with either compound, but RO-838 led to non-significant increases in triglycerides and VLDL-cholesterol versus placebo. Both compounds were well tolerated and showed inhibitory effects on 11β-HSD1 activity based on urinary corticosteroid excretion. As reported for other 11β-HSD1-inhibitors increased concentrations of ACTH and adrenal androgen precursors were found with RO-151, but not with RO-838.

CONCLUSIONS

Slight metabolic improvements were seen, in particular with RO-151 high dose, however, the observed changes often did not reach statistical significance and were not clearly dose dependent. Studies of longer duration are needed to further investigate potential benefits and risks of these compounds.

Steady-state pharmacokinetics and glucodynamics of the novel, long-acting basal insulin LY2605541 dosed once-daily in patients with type 2 diabetes mellitus

AIMS

To assess the pharmacokinetics (PK) and glucodynamics (GD) of LY2605541 in patients with type 2 diabetes mellitus.

METHODS

This parallel-group, open-label, dose-escalation study examined the PK and GD of basal insulin LY2605541 after single and multiple-dose administration. Fixed doses of LY2605541 (0.33-1.00 U/kg) were given once-daily (QD) for 14 days to insulin-treated patients with type 2 diabetes. A 24-h euglycaemic glucose clamp was conducted on days 1 and 14.

RESULTS

PK steady state was achieved within 7-10 days and the peak-to-trough fluctuation was <2, translating to a nearly 'peakless' glucose infusion rate at steady state and with a duration of action of at least 24 h. Across dose levels t1/2 ranged from 44.7 to 75.5 h (~2-3 days). As steady state was achieved, there were dose-dependent reductions in the prandial insulin dose and in fasting blood glucose, which decreased to 60-100 mg/dl across dose levels. Within-patient variability was <14 and <26% for the area under the concentration versus time curve (AUC) of the 8-point blood glucose profile and fasting blood glucose, respectively. The nocturnal glucose control between 03:00 and 09:00 hours was relatively unchanged. Mild hypoglycaemia was the most common adverse event.

CONCLUSIONS

In this Phase I study of fixed LY2605541 doses without titration, LY2605541 was well-tolerated and demonstrated a flat PK and GD profile accompanied by glucose normalization, prandial insulin dose reduction and no severe hypoglycaemia.

Interleukin-1 antagonism in type 1 diabetes of recent onset: two multicentre, randomised, double-blind, placebo-controlled trials

BACKGROUND

Innate immunity contributes to the pathogenesis of autoimmune diseases, such as type 1 diabetes, but until now no randomised, controlled trials of blockade of the key innate immune mediator interleukin-1 have been done. We aimed to assess whether canakinumab, a human monoclonal anti-interleukin-1 antibody, or anakinra, a human interleukin-1 receptor antagonist, improved β-cell function in recent-onset type 1 diabetes.

METHODS

We did two randomised, placebo-controlled trials in two groups of patients with recent-onset type 1 diabetes and mixed-meal-tolerance-test-stimulated C peptide of at least 0·2 nM. Patients in the canakinumab trial were aged 6-45 years and those in the anakinra trial were aged 18-35 years. Patients in the canakinumab trial were enrolled at 12 sites in the USA and Canada and those in the anakinra trial were enrolled at 14 sites across Europe. Participants were randomly assigned by computer-generated blocked randomisation to subcutaneous injection of either 2 mg/kg (maximum 300 mg) canakinumab or placebo monthly for 12 months or 100 mg anakinra or placebo daily for 9 months. Participants and carers were masked to treatment assignment. The primary endpoint was baseline-adjusted 2-h area under curve C-peptide response to the mixed meal tolerance test at 12 months (canakinumab trial) and 9 months (anakinra trial). Analyses were by intention to treat. These studies are registered with ClinicalTrials.gov, numbers NCT00947427 and NCT00711503, and EudraCT number 2007-007146-34.

FINDINGS

Patients were enrolled in the canakinumab trial between Nov 12, 2010, and April 11, 2011, and in the anakinra trial between Jan 26, 2009, and May 25, 2011. 69 patients were randomly assigned to canakinumab (n=47) or placebo (n=22) monthly for 12 months and 69 were randomly assigned to anakinra (n=35) or placebo (n=34) daily for 9 months. No interim analyses were done. 45 canakinumab-treated and 21 placebo-treated patients in the canakinumab trial and 25 anakinra-treated and 26 placebo-treated patients in the anakinra trial were included in the primary analyses. The difference in C peptide area under curve between the canakinumab and placebo groups at 12 months was 0·01 nmol/L (95% CI -0·11 to 0·14; p=0·86), and between the anakinra and the placebo groups at 9 months was 0·02 nmol/L (-0·09 to 0·15; p=0·71). The number and severity of adverse events did not differ between groups in the canakinumab trial. In the anakinra trial, patients in the anakinra group had significantly higher grades of adverse events than the placebo group (p=0·018), which was mainly because of a higher number of injection site reactions in the anakinra group.

INTERPRETATION

Canakinumab and anakinra were safe but were not effective as single immunomodulatory drugs in recent-onset type 1 diabetes. Interleukin-1 blockade might be more effective in combination with treatments that target adaptive immunity in organ-specific autoimmune disorders.

FUNDING

National Institutes of Health and Juvenile Diabetes Research Foundation.

The duration of sulfonylurea treatment is associated with β-cell dysfunction in patients with type 2 diabetes mellitus

BACKGROUND

This study investigated the incidence of β-cell dysfunction and the clinical and biochemical factors affecting that in patients with type 2 diabetes having more than 3 years of follow-up.

SUBJECTS AND METHODS

β-Cell dysfunction was assessed by measuring changes in the fasting serum C-peptide concentrations. Patients were classified into two groups: cases showing a decreased (Group D) or an unchanged or increased (Group I) C-peptide concentration from the baseline.

RESULTS

Of the 504 patients included in this study, 259 (51%) showed decreased C-peptide concentrations, of whom 20% showed a decrease of ≥50%. Most patients, however, had a final C-peptide concentration of ≥1 ng/mL, with only 18 (4%) individuals having a level <0.6 ng/mL. Patients in Group D had a longer duration of diabetes, higher initial hemoglobin A1c concentration, and longer treatment durations with sulfonylurea and insulin compared with Group I. After adjusting for diabetes duration and C-peptide follow-up period, the duration of sulfonylurea treatment was found to be the only factor independently associated with decreases in the C-peptide concentration.

CONCLUSIONS

Although β-cell function deteriorates over time in patients with type 2 diabetes, these cases mainly have fasting serum C-peptide concentrations of ≥1 ng/mL. A longer treatment duration with sulfonylurea is associated with a more rapid decline in the C-peptide concentration.

Effects of a single post-partum injection of a high dose of vitamin D on glucose tolerance and insulin resistance in mothers with first-time gestational diabetes mellitus

AIM

This study was performed to determine the effect of a single, large, intramuscular injection of vitamin D post-partum on glucose tolerance and insulin resistance in women with gestational diabetes.

METHODS

Forty-five participants in a randomized controlled trial on gestational diabetes mellitus were divided into an intervention group and a control group. Only subjects in the intervention group received one intramuscular injection of 300,000 IU of vitamin D3. HbA(1c), serum 25-hydroxyvitamin D3, fasting insulin and blood glucose, C-peptide, homeostasis model assessment insulin resistance index (HOMA-IR), β-cell function, insulin sensitivity and the Quantitative Insulin Sensitivity Check Index (QUICKI) were measured at baseline and after 3 months of intervention.

RESULTS

Approximately 80% of the mothers had a degree of vitamin D deficiency. Post-intervention, this was found in 4.2 and 71.4% in the intervention and control groups, respectively. The medians of HOMA-IR indices before and after intervention were 0.6 and 0.5 (P = 0.7), respectively, in subjects in the intervention group, and 0.5 and 0.9 (P = 0.01) in subjects in the control group. The mean of the QUICKI fell only in the control group (P = 0.008). In the control group, β-cell function increased by ~8% (P = 0.01) and insulin sensitivity decreased after 3 months (P = 0.002). Post-intervention, the median C-peptide decreased in the intervention group and increased in the control group, but the change was significant only in the control group (P = 0.03).

CONCLUSIONS

A single injection of 300,000 IU of vitamin D3 achieves a 3-month serum 25-hydroxyvitamin D range of 50-80 nmol/l and is an efficient, effective and safe procedure for improving the vitamin status and indices of insulin resistance in mothers with gestational diabetes after delivery.

Effect of initial combination therapy with sitagliptin and metformin on β-cell function in patients with type 2 diabetes

AIM

To examine the effect of sitagliptin and metformin, alone and in combination, on modelled parameters of β-cell function in patients with type 2 diabetes.

METHODS

The data used in the present analyses are from a 104-week study, which included a 24-week, placebo- and active controlled phase followed by a 30-week, active controlled, continuation phase and an additional 50-week, active controlled extension phase. Patients were randomised to one of six blinded treatments: sitagliptin 50 mg + metformin 1000 mg b.i.d., sitagliptin 50 mg + metformin 500 mg b.i.d., metformin 1000 mg b.i.d., metformin 500 mg b.i.d., sitagliptin 100 mg q.d. or placebo. Patients on placebo were switched in a blinded manner to metformin 1000 mg b.i.d. at week 24. Subsets of patients volunteered to undergo frequently sampled meal tolerance tests at baseline and at weeks 24, 54 and 104. β-cell responsivity was assessed with the C-peptide minimal model. The static component (Φ(s)) estimates the rate of insulin secretion related to above-basal glucose concentration. The dynamic component (Φ(d)) is related to the rate of change in glucose. The total index (Φ(total)) represents the overall response to a glycaemic stimulus and is calculated as a function of Φ(s) and Φ(d). Insulin sensitivity was estimated with the Matsuda index (ISI). The disposition index, which assesses insulin secretion relative to the prevailing insulin sensitivity, was calculated based on the Φ(total) and ISI.

RESULTS

At week 24, substantial reductions in postmeal glucose were observed with all active treatment groups relative to the placebo group. Φ(s), Φ(total) and the disposition index were significantly improved from baseline at week 24 with all active treatments relative to placebo. Generally larger effects were observed with the initial combination of sitagliptin and metformin relative to the monotherapy groups. When expressed as median percent change from baseline, Φ(s) increased from baseline by 137 and 177% in the low- and high-dose combination groups and by 85, 54, 73 and -9% in the high-dose metformin, low-dose metformin, sitagliptin monotherapy and placebo groups, respectively. At weeks 54 and 104, the combination treatment groups continued to demonstrate greater improvements in β-cell function relative to their respective monotherapy groups.

CONCLUSIONS

After 24 weeks of therapy, relative to placebo, initial treatment with sitagliptin or metformin monotherapy improved β-cell function; moreover, initial combination therapy demonstrated larger improvements than the individual monotherapies. Improvements in β-cell function were found with treatments for up to 2 years.

Triple oral fixed-dose diabetes polypill versus insulin plus metformin efficacy demonstration study in the treatment of advanced type 2 diabetes (TrIED study-II)

AIM

To compare the efficacy of a fixed-dose triple oral diabetes polypill containing 1 or 2 mg glimepiride, 500 mg sustained-release metformin, and 15 mg pioglitazone (GMP) administered once daily with human insulin 70/30 mix and 500 mg sustained-release metformin administered twice daily (IM) in insulin-naÏve subjects with type 2 diabetes mellitus inadequately controlled [haemoglobin A1c (HbA1c) over 8.0%] on a combination of glimepiride and metformin.

METHODS

One hundred and one subjects were randomized to GMP or IM regimens for 12 weeks. The primary outcome was the change in HbA1c and secondary outcomes were changes in fasting plasma, and postprandial plasma glucoses and the number of patients achieving a drop in HbA1c of over 1%. Other secondary outcomes were changes in the lipid profile, C-peptide level, body weight as well as physician assessments of efficacy and patient assessment of tolerability.

RESULTS

The primary outcome of a change in HbA1c showed a trend towards a lower HbA1c with GMP therapy (-1.33% vs. -0.83%; p = 0.059). The number of subjects achieving a decrease in HbA1c of greater than 1.0% was significantly greater in the GMP therapy (72.5% vs. 22%; p = 0.0001). Both regimens equally and significantly reduced fasting and postprandial glucose levels (p = 0.05). Weight gain was nonsignificantly greater with IM (2.69 vs. 0.92 kg; p = 0.223). Investigator assessment of efficacy was significantly better with GMP (p = 0.001) as was tolerability as assessed by patients (p = 0.0001).

CONCLUSION

When compared with suboptimally titrated IM there was a trend towards a lower HbA1c with GMP and significantly more GMP subjects obtained an HbA1c under 7%. Global assessments by investigators and subjects showed both a greater efficacy and tolerability with GMP.

Glucose-dependent insulinotropic polypeptide may enhance fatty acid re-esterification in subcutaneous abdominal adipose tissue in lean humans

OBJECTIVE

Glucose-dependent insulinotropic polypeptide (GIP) has been implicated in lipid metabolism in animals. In humans, however, there is no clear evidence of GIP effecting lipid metabolism. The present experiments were performed in order to elucidate the effects of GIP on regional adipose tissue metabolism.

RESEARCH DESIGN AND METHODS

Eight healthy subjects were studied on four different occasions. Abdominal subcutaneous adipose tissue metabolism was assessed by measuring arterio-venous concentration differences and regional adipose tissue blood flow during GIP (1.5 pmol/kg/min) or saline infused intravenously alone or in combination with a hyperinsulinemic-hyperglycemic (HI-HG) clamp.

RESULTS

During GIP and HI-HG clamp, abdominal subcutaneous adipose tissue blood flow, hydrolysis of circulating triacylglycerol (TAG) (P = 0.009), and glucose uptake (P = 0.03) increased significantly while free fatty acid (FFA) output (P = 0.04) and FFA/glycerol release ratio (P = 0.02) decreased compared with saline and HI-HG clamp.

CONCLUSIONS

In conclusion, GIP in combination with hyperinsulinemia and slight hyperglycemia increased adipose tissue blood flow, glucose uptake, and FFA re-esterification, thus resulting in increased TAG deposition in abdominal subcutaneous adipose tissue.

A dose range finding study of novel oral insulin (IN-105) under fed conditions in type 2 diabetes mellitus subjects

AIM

The objective of the study was to establish the dose response of IN-105 tablets and explore a possible therapeutic window in type 2 diabetes subjects poorly controlled on metformin.

METHODS

The primary objective was to examine the effect of sequential single ascending doses of IN-105 on the plasma glucose concentration under fed conditions. All subjects received, sequentially, matching placebo, 10, 15, 20 and 30 mg IN-105 tablets in five consecutive periods. Tablets were administered 20 min prior to meal in all the periods. Plasma levels of immunoreactive insulin, C-peptide and glucose were measured up to 180 min from the time of dosing. The changes in postprandial glucose levels at 120 min in response to IN-105 administration were also compared against those of placebo.

RESULTS

Changes in glucose from baseline (mean +/- s.d.) at 140 min (2 h postprandial) were 94.84 +/- 22.3, 79.45 +/- 43.00, 70.68 +/- 35.71, 63.47 +/- 42.75 and 53.06 +/- 47.27 mg/dL, respectively, and exhibited linear dose-response. The insulin C(max) values were found to be 50.8 +/- 26.0 mU/L for placebo, 100.3 +/- 66.7 with 10 mg IN-105, 177.69 +/- 150.3 with 15 mg IN-105, 246.2 +/- 245.2 with 20 mg IN-105 and 352.5 +/- 279.3 mU/L with 30 mg of IN-105.

CONCLUSIONS

IN-105 absorption is proportional to the dose administered. The 2-h postprandial glucose excursion was reduced in a dose proportional manner. Circulating C-peptide levels were found to be suppressed in proportion to the IN-105 exposure. IN-105 reduces glucose excursion despite lower endogenous insulin secretion. IN-105 seems to have a wide therapeutic window as no clinical hypoglycaemia was observed at any of the doses studied.

Effect of glucagon-like peptide-1 on alpha- and beta-cell function in C-peptide-negative type 1 diabetic patients

CONTEXT

The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect.

OBJECTIVE

To characterize the alpha- and beta-cell responses to GLP-1 in type 1 diabetic patients without residual beta-cell function.

METHODS

Nine type 1 diabetic patients, classified as C-peptide negative by a glucagon test, were clamped at plasma glucose of 20 mmol/liter for 90 min with arginine infusion at time 45 min and concomitant infusion of GLP-1 (1.2 pmol/kg x min) or saline.

RESULTS

Infusion with GLP-1 increased C-peptide concentration just above the detection limit of 33 pmol/liter in one patient, but C-peptide remained immeasurable in all other patients. In the eight remaining patients, total area under the curve of glucagon was significantly decreased with GLP-1 compared with saline: 485 +/- 72 vs. 760 +/- 97 pmol/liter x min (P < 0.001). In addition, GLP-1 decreased the arginine-stimulated glucagon release (incremental AUC of 103 +/- 21 and 137 +/- 16 pmol/liter x min, with GLP-1 and saline, respectively, P < 0.05).

CONCLUSIONS

In type 1 diabetic patients without endogenous insulin secretion, GLP-1 decreases the glucagon secretion as well as the arginine-induced glucagon response during hyperglycemia. GLP-1 induced endogenous insulin secretion in one of nine type 1 diabetic patients previously classified as being without endogenous insulin secretion.

Open-label study to assess the safety and pharmacodynamics of five oral insulin formulations in healthy subjects

AIM

Orally delivered insulin is predicted to bear therapeutic advantages in diabetes management when compared to injectable insulin, because of its ability to mimic the natural route of endogenous insulin secreted by the pancreas into the portal vein and directly to the liver. Oramed Pharmaceuticals is developing an oral insulin product which consists of unmodified recombinant human insulin combined with adjuvants that protect it from enzymatic degradation in the gastrointestinal tract and promote its absorption from the gut. The aim was to determine the optimal adjuvants to insulin ratio which can provide for the best pharmacodynamic profile, while maintaining the safety of the product.

METHODS

Eight healthy, male volunteers participated in this open-label study which included five independent visits. During each visit, subjects were administered one of the five encapsulated oral insulin formulations which contained equal amounts of insulin but varying proportions of adjuvants. Parameters measured included safety, C(max) and T(max) for insulin and C(min), T(min) and area under the curve (AUC) for glucose and c-peptide. Comparisons were made between formulations and between post-treatment time periods within each visit.

RESULTS

All five oral insulin formulations were well tolerated and no serious adverse events were reported. All formulations resulted in a significant response in the response period (60-300 min) in comparison to baseline (0-60 min); this was captured both in the c-peptide response and the glucose response (all five formulations p < 0.05). However, none of the formulations turned out significantly different in response over the other. Formulation 5 showed the most profound reduction in c-peptide when AUC(0-60) (baseline) was compared to AUC(60-300) (p < 0.007).

CONCLUSIONS

All five oral insulin formulations resulted in glucose and c-peptide reductions, where formulation 5 demonstrated the most pronounced effect on c-peptide concentration reduction. This formulation was deemed the lead formulation to be advanced to future clinical studies. This study also reinforces the notion that oral insulin can maintain its biological activity after delivery, suggesting a potential role for this product in management of diabetes.

Improved diabetic control during oral sulfonylurea treatment in two children with permanent neonatal diabetes mellitus

Permanent neonatal diabetes mellitus (PND), defined as diabetes diagnosed in the first 6 months of age and requiring life-long insulin therapy, is a rare disorder of unknown etiology. Activating mutations of the KCNJ11 gene, which encodes the Kir6.2 subunit of the ATP-dependent potassium channel in beta-cells, have been found to cause 30-58% of cases of PND. Sulfonylurea treatment in theses patients reduces or eliminates the need for exogenous insulin. We report two Taiwanese boys who were diagnosed with PND at 1 and 4.5 months of age. They had been treated with exogenous insulin for 6 and 15 years, respectively. In September 2006, they were both found to have a KCNJ11 mutation (valine-to-methionine at codon 59; V59M). Glibenclamide successfully increased the basal C-peptide level, lowered HbA(1c), and reduced blood sugar excursions. In one patient, the insulin dose was reduced to 0.2 U/kg/day, and the other was able to discontinue insulin altogether. These two cases from Taiwan add to the experience with similar mutations reported in Caucasians.

Protective effects of 1-alpha-hydroxyvitamin D3 on residual beta-cell function in patients with adult-onset latent autoimmune diabetes (LADA)

BACKGROUND

Previous in vitro and in vivo studies have demonstrated that vitamin D could prevent pancreatic beta-cell destruction and reduce the incidence of autoimmune diabetes. In children with type 1 diabetes, vitamin D treatment produces moderate protective effects on residual beta-cell function and has proven to be safe. Therefore, we hypothesized that vitamin D might have protective effects on beta-cell function in patients with latent autoimmune diabetes in adults (LADA), a form of slowly progressive autoimmune type 1 diabetes.

METHODS

Thirty-five patients with LADA were randomly assigned to receive subcutaneous insulin alone (n = 18) or insulin plus 1-alpha-hydroxyvitamin D3 (1-alpha(OH)D3; 0.5 microg per day) (n = 17) for 1 year. Plasma C-peptide levels in fasting state (FCP) and 2 h after 75-g glucose load (PCP) were measured every 6 months with radioimmunoassay.

RESULTS

Both FCP and PCP levels stayed steady in the insulin plus 1-alpha(OH)D3 group, while FCP decreased in insulin-alone group (P = 0.006) during the 12-month intervention. Seventy percent of patients treated with 1-alpha(OH)D3 maintained or increased their FCP concentrations after 1 year of treatment, while only 22% of patients treated with insulin alone maintained stable FCP levels (P < 0.01). Further analysis on LADA subgroups with different durations of diabetes demonstrated that islet beta-cell function was better preserved (as reflected by significantly higher FCP and PCP levels) in the 1-alpha(OH)D3 plus insulin group only in patients with diabetes duration no longer than 1 year. No severe side effects were observed in any group.

CONCLUSION

Our data suggest that 1-alpha(OH)D3 plus insulin therapy can preserve pancreatic beta-cell function in patients with LADA.

Ability of GHTD-amide and analogs to enhance insulin activity through zinc chelation and dispersal of insulin oligomers

GHTD-amide is a tetrapeptide originally isolated from human urine that has hypoglycemic activity. Insulin occurs in secretory granules of beta cells as zinc-stabilized hexamers and must disperse to monomeric form in order to bind to its receptor. The aim of this study was to identify whether GHTD-amide and an analog called ISF402 (VHTD-amide) reduce blood glucose through enhancement of insulin activity by dispersing oligomers of insulin. Peptides containing the HTD-amide sequence and a free alpha-amino group were optimal at binding Zn(2+) and adopting secondary structure in the presence of Zn(2+). Binding was concentration dependent and resulted in a 1:1 Zn:peptide complex. In vitro the tetrapeptides dispersed hexameric insulin to dimers and monomers. GHTD-amide and ISF402 potentiated the activity of hexameric insulin when co-injected into insulin resistant Zucker rats. Injection of peptides with insulin caused reductions in blood glucose and C-peptide significantly larger than achieved with insulin alone, and serum insulin time profiles were also altered consistent with a reduced clearance or enhanced dispersal of the injected insulin. Insulin potentiation by ISF402 was reduced when lispro insulin, which does not form zinc-stabilized hexamers, was used in place of hexameric zinc insulin. In conclusion, GHTD-amide and ISF402 are zinc binding peptides that disperse hexameric insulin in vitro, and potentiate the activity of hexameric insulin more so than monomeric lispro insulin. These results suggest that dispersal of hexameric insulin through chelation of Zn(2+) contributes to the hypoglycemic activity of these tetrapeptides.

Immune modulation in type 1 diabetes mellitus using DiaPep277: a short review and update of recent clinical trial results

In type 1 diabetes mellitus, autoimmune T-cells mount an attack on insulin producing beta-cells eventually causing hyperglycemia. It is hypothesized, that to prevent and treat this disease, one must interfere with the autoimmune process. To avoid hazardous side effects, this intervention should not cause a global immune suppression but immune modulation. DiaPep277 (peptide 277) is a 24 amino acid peptide derived from positions 437-460 in HSP60. It has recently been shown to have an immune modulatory effect on diabetogenic T cells in animal models of diabetes. It has also been recently implicated as a possible auto-antigen in type 1 diabetes. Promising results in animal models led to phase 1 to 3 human clinical trials in patients with type 1 diabetes, the results of which are the focus of this review. A combined analysis of all the adult phase II studies revealed that DiaPep277 significantly inhibits the decline in stimulated C-peptide secretion (thus preserving endogenous insulin secretion). This effect was more pronounced in patients with a high beta-cell reserve at the start of the treatment. Furthermore, opposite trends in glycemic control of DiaPep277 treated patients where noted as opposed to placebo treated patients. The phase III study has began more than 2 years ago in 40 medical centers worldwide, and thus far recruited over 350 patients around the world. If DiaPep277 will prove to be efficacious, it will cause a paradigm shift in the treatment of type 1 diabetes, from treating the subsequent insulin deficiency to addressing the initial autoimmune process that is at the heart of the disease.

Cyclical and alternating infusions of glucose and intralipid in rats inhibit insulin gene expression and Pdx-1 binding in islets

OBJECTIVE

Prolonged exposure of isolated islets of Langerhans to elevated levels of fatty acids, in the presence of high glucose, impairs insulin gene expression via a transcriptional mechanism involving nuclear exclusion of pancreas-duodenum homeobox-1 (Pdx-1) and loss of MafA expression. Whether such a phenomenon also occurs in vivo is unknown. Our objective was therefore to ascertain whether chronic nutrient oversupply inhibits insulin gene expression in vivo.

RESEARCH DESIGN AND METHODS

Wistar rats received alternating 4-h infusions of glucose and Intralipid for a total of 72 h. Control groups received alternating infusions of glucose and saline, saline and Intralipid, or saline only. Insulin and C-peptide secretion were measured under hyperglycemic clamps. Insulin secretion and gene expression were assessed in isolated islets, and beta-cell mass was quantified by morphometric analysis.

RESULTS

Neither C-peptide secretion nor insulin sensitivity was different among infusion regimens. Insulin content and insulin mRNA levels were lower in islets isolated from rats infused with glucose plus Intralipid. This was associated with reduced Pdx-1 binding to the endogenous insulin promoter, and an increased proportion of Pdx-1 localized in the cytoplasm versus the nucleus. In contrast, MafA mRNA and protein levels and beta-cell mass and proliferation were unchanged.

CONCLUSIONS

Cyclical and alternating infusions of glucose and Intralipid in normal rats inhibit insulin gene expression without affecting insulin secretion or beta-cell mass. We conclude that fatty acid inhibition of insulin gene expression, in the presence of high glucose, is an early functional defect that may contribute to beta-cell failure in type 2 diabetes.

Effects of chili consumption on postprandial glucose, insulin, and energy metabolism

BACKGROUND

Animal and some human studies have indicated that the consumption of chili-containing meals increases energy expenditure and fat oxidation, which may help to reduce obesity and related disorders. Because habitual diets affect the activity and responsiveness of receptors involved in regulating and transporting nutrients, the effects of regular consumption of chili on metabolic responses to meals require investigation.

OBJECTIVE

The objective was to investigate the metabolic effects of a chili-containing meal after the consumption of a bland diet and a chili-blend (30 g/d; 55% cayenne chili) supplemented diet.

DESIGN

Thirty-six subjects with a mean (+/-SD) age of 46 +/- 12 y and a body mass index (in kg/m2) of 26.3 +/- 4.6 participated in a randomized, crossover, intervention study with 2 dietary periods (chili and bland) of 4 wk each. The postprandial effects of a bland meal after a bland diet (BAB), a chili meal after a bland diet (CAB), and a chili meal after a chili-containing diet (CAC) were evaluated. Serum insulin, C-peptide, and glucose concentrations and energy expenditure (EE) were measured at fasting and up to 120 min postprandially.

RESULTS

Significant heterogeneity was observed between the meals for the maximum increase in insulin and the incremental area under the curve (iAUC) for insulin (P = 0.0002); the highest concentrations were with the BAB meal and the lowest with the CAC meal. When separated at the median BMI (26.3), the subjects with a BMI > or = 26.3 also showed heterogeneity in C-peptide, iAUC C-peptide, and net AUC EE (P < 0.02 for all); the highest values occurred after the BAB meal and the lowest after the CAC meal. Conversely, the C-peptide/insulin quotient (an indicator of hepatic insulin clearance) was highest after the CAC meal (P = 0.002).

CONCLUSION

Regular consumption of chili may attenuate postprandial hyperinsulinemia.

Effect of atorvastatin (10 mg/day) on glucose metabolism in patients with the metabolic syndrome

Large interventional studies have shown that statins may reduce the incidence of type 2 diabetes mellitus. However, it is uncertain whether short-term statin therapy can affect insulin sensitivity in patients with the metabolic syndrome. We evaluated the effect of atorvastatin (10 mg/day) in 10 insulin-resistant subjects (age 40 +/- 12 years, body mass index 33.6 +/- 5.2 kg/m(2), triglycerides 2.84 +/- 1.99 mmol/L [249 +/- 175 mg/dl], glucose 6.06 +/- 0.67 mmol/L [109 +/- 12 mg/dl)] using the homeostasis model assessment (HOMA) index (parameter of insulin resistance derived from fasting glucose and fasting insulin concentrations; 5.7 +/- 2.6) in a randomized placebo-controlled, double-blind, crossover study. Subjects were randomized to receive placebo or atorvastatin, each given for 6 weeks separated by a 6-week wash-out period. At the beginning and end of each treatment phase, the patients underwent an oral glucose tolerance test, a 72-hour continuous glucose measurement, and a detailed lipid determination, including a standardized fat tolerance test. Compared with placebo, atorvastatin resulted in a significant (p = 0.05) reduction in the HOMA index (-21%), fasting C-peptides (-18%), glucose (area under the curve during the oral glucose tolerance test, -7%), and a borderline (p = 0.08) reduction of insulin (-18%). The parameters derived from the continuous 72-hour glucose monitoring did not change. A significant reduction also occurred in the total and low-density lipoprotein cholesterol concentrations, although the fasting and postprandial triglyceride concentrations did not change significantly. However, we found a significant correlation between atorvastatin-induced changes in the HOMA and baseline HOMA and between the atorvastatin-induced changes in triglycerides and insulin concentrations. The free-fatty acid, interleukin-6, and high sensitivity C-reactive protein concentrations did not change. Our data indicated that in insulin-resistant, nondiabetic subjects, 6 weeks of atorvastatin (10 mg/day) resulted in significant improvement in insulin sensitivity.

Improved prandial glucose control with lower risk of hypoglycemia with nateglinide than with glibenclamide in patients with maturity-onset diabetes of the young type 3

OBJECTIVE

To study the effect of the short-acting insulin secretagogue nateglinide in patients with maturity-onset diabetes of the young type 3 (MODY3), which is characterized by a defective insulin response to glucose and hypersensitivity to sulfonylureas.

RESEARCH DESIGN AND METHODS

We compared the acute effect of nateglinide, glibenclamide, and placebo on prandial plasma glucose and serum insulin, C-peptide, and glucagon excursions in 15 patients with MODY3. After an overnight fast, they received on three randomized occasions placebo, 1.25 mg glibenclamide, or 30 mg nateglinide before a standard 450-kcal test meal and light bicycle exercise for 30 min starting 140 min after the ingestion of the first test drug.

RESULTS

Insulin peaked earlier after nateglinide than after glibenclamide or placebo (median [interquartile range] time 70 [50] vs. 110 [20] vs. 110 [30] min, P = 0.0002 and P = 0.0025, respectively). Consequently, compared with glibenclamide and placebo, the peak plasma glucose (P = 0.031 and P < 0.0001) and incremental glucose areas under curve during the first 140 min of the test (P = 0.041 and P < 0.0001) remained lower after nateglinide. The improved prandial glucose control with nateglinide was achieved with a lower peak insulin concentration than after glibenclamide (47.0 [26.0] vs. 80.4 [71.7] mU/l; P = 0.023). Exercise did not induce hypoglycemia after nateglinide or placebo, but after glibenclamide six patients experienced symptomatic hypoglycemia and three had to interrupt the test.

CONCLUSIONS

A low dose of nateglinide prevents the acute postprandial rise in glucose more efficiently than glibenclamide and with less stimulation of peak insulin concentrations and less hypoglycemic symptoms.

Antiepileptic drugs alter reproductive endocrine hormones in men with epilepsy

Disturbances of reproductive endocrine hormones are more often found in men with epilepsy than in the general population. There is an ongoing debate whether this can be attributed to chronic use of antiepileptic drugs or to the epilepsy itself. The aim of the present study was to evaluate the degree of endocrine disturbances in men with epilepsy compared with healthy controls, and to investigate whether there was a drug-specific effect of valproate (VPA) or carbamazepine (CBZ). Men with epilepsy, 20-40 years old, having used either VPA (n = 16) or CBZ (n = 19) as monotherapy for >2 years were included and compared with age-matched controls. Men with epilepsy (VPA + CBZ) had significantly lower FSH values and higher C-peptide values compared with controls. Regarding possible drug-specific effects, the VPA treated patients had significantly higher dehydroepiandrosterone (DHEAS) levels and lower FSH and LH concentrations compared with the controls, whereas there were no differences in testosterone, testosterone/sexhormone-binding globulin (SHBG) ratio or androstenedione levels. Men on VPA also had significantly lower free carnitine/total carnitine, which may have implications for sperm motility, and also higher insulin and C-peptide concentrations. The CBZ treated patients had significantly lower testosterone/SHBG ratio than the controls. Compared with the CBZ treated patients, men on VPA had significantly higher DHEAS concentrations and lower levels of follicle stimulating hormone (FSH), luteinizing hormone (LH) as well as a lower free carnitine/total carnitine ratio. A marked age dependency was found in all three groups regarding several of the endocrine hormones. In conclusion, drug-specific endocrine effects of VPA and CBZ were found in men with epilepsy. Long-term VPA treatment leads to significant changes in DHEAS, FSH, LH, insulin, C-peptide and carnitine ratio. Long-term CBZ treatment leads to significant lower testosterone/SHBG ratio. A strict age matching were found to be of importance in the evaluation of endocrine function in men.

Effects of taurine in glucose and taurine administration

Taurine has several biological processes such as hypoglycemic action, antioxidation, detoxification, etc. To assess the effect of taurine administration on the guinea pigs with hyperglycemia, blood glucose, C-peptide levels together with morphologic alterations in the pancreatic ultrastructure were investigated in terms of hypoglycemic action and malondialdehyde and total sulfhydryl group levels with regard to oxidation-antioxidation relation. Animals were divided into four groups of six. Glucose supplementation group was administrated a single dose of glucose (400 mg/kg, i.p.) injection. Glucose and taurine supplementation group was administrated glucose treatment (a single dose, 400 mg/kg, i.p.) following taurine (a single dose, 200 mg/kg, i.p.). Taurine and glucose supplementation group was administered taurine treatment (a single dose, 200 mg/kg, i.p.) following glucose treatment (a single dose, 400 mg/kg, i.p.). Control animals received no treatment. Blood samples were collected at the end of the experiments for the determination of glucose, C-peptide (indicator of insulin secretion), lipid peroxidation (thiobarbituric acid reactive substances), and total sulfhydryl groups levels. Pancreatic tissue samples were then collected and processed for transmission electron microscopy. The findings showed that glucose supplementation following taurine administration significantly decreased blood glucose level by increasing C-peptide level and the pancreatic secretion stimulated morphologically and insignificantly changed thiobarbituric acid reactive substances and total sulfhydryl group levels. These observations suggest that taurine administration may be useful in hyperglycemia because of its hypoglycemic and protective effects.

[Efficiency of the vegetative tea in diet therapy for patients with obesity associated with diabetes mellitus type 2]

The dynamic of glycemia, insulin, C-peptide, glycosylated hemoglobin, fructosamine, thyroid hormones, parameters of serum lipids, lipid peroxidation and system of antioxidant defense in 81 hospital patients and out-patients with obesity associated with diabetes mellitus type II was studied of influence of hypocaloric diet 9. Universal normalizing influence of hypocaloric diet 9 with vegetation tea was discovered on parameters of carbohydrate, lipid and oxidative metabolism and of patients clinical state of pateni. The additional criteria of evaluation of efficacy of food dietary supplements in complex treatment of patients with obesity associated with diabetes mellitus type II was offered on basis of study of influence vegetation tea on mechanisms of metabolic disorders in these patients.

Effect of metformin on insulin sensitivity and insulin secretion in female obese patients with normal glucose tolerance

OBJECTIVES

Metformin is recognized as the treatment of chronic obese, insulin-resistant type 2 diabetic patients. Whether it improves insulin sensitivity in obese patients with normal glucose tolerance remains unknown.

METHODS

Eight obese female patients with normal glucose tolerance were studied during a double blinded, randomized cross-over study including a 2-week administration of metformin and a 2-week administration of placebo. Insulin secretion and insulin sensitivity were assessed after metformin and placebo by means of a 3-hour hyperglycemic clamp.

RESULTS

The plasma insulin and C-peptide concentrations during the hyperglycemic clamp were identical after placebo or metformin (both first and second phases). Insulin-mediated glucose disposal, stimulation of glucose oxidation and suppression of endogenous glucose production were identical after metformin and placebo.

CONCLUSIONS

Metformin does not improve insulin sensitivity nor insulin secretion in obese female patients with normal glucose tolerance.

L-carnitine consecutively administered to patients on hemodialysis improves beta-cell response

Eight patients with end stage renal disease (ESRD) on chronic hemodialysis (CHD) treatment were supplemented with 1 g L-carnitine intravenously (i.v.) after each dialysis session for one month. A Tolbutamide test was done and blood sugar (BS), serum C-peptide (CP) were measured at 0, 20 and 60 minutes, as well as the plasma L-carnitine level before and after treatment. Delta CP and the area under CP curve were ascertained. After L-carnitine application delta CP was significantly increased (1.33 +/- 0.63 vs. 2.24 +/- 1.0 nmol/L; p<0.05) and also the area of the stimulated secretion under the CP curve (14.93 +/- 11.11 vs. 36.88 +/- 25.36 nmol/L x 60 min.; p<0.05). The fasting BS-level was significantly lower after the treatment--3.85 +/- 0.43 vs. 4.76 +/- 1.02 mmol/L; p<0.05 and plasma L-carnitine level significantly increased (72.8 +/- 43.2 vs. 35.2 +/- 18.3 mcmol/L; p<0.05) Improving the oxidative processes in peripheral tissues, L-carnitine increases the peripheral effectiveness of insulin and relieves the overstretched beta-cell apparatus.

Hormone replacement therapy does not affect plasma homocysteine in postmenopausal women with coronary artery disease. Free tissue factor pathway inhibitor antigen, a circulating anticoagulant, is related to plasma homocysteine

OBJECTIVE

The objective was to evaluate the effect of hormone replacement therapy (HRT) on plasma homocysteine levels in postmenopausal women with coronary artery disease (CAD) and to investigate associations of homocysteine to other cardiovascular risk factors.

METHODS

The women in this single-center, controlled, and randomized study were examined at baseline, and after 3 and 12 months, after they had been recruited consecutively from patients referred for investigational coronary angiography. All analyses were performed examiner blind. They were randomized to HRT consisting of transdermal application of continuous 17beta-estradiol with cyclic medroxyprogesterone acetate (MPA) tablets for 14 days every 3rd month, or to a control group.

RESULTS

After 3 months of unopposed 17beta-estradiol, no significant effect on homocysteine was observed compared to the control group. The absolute decrease of 5% in median plasma homocysteine levels after 12-month HRT did not reach statistical significance. Plasma homocysteine seemed slightly higher in women with three- or four-vessel disease, but the difference was not significant. With increasing homocysteine levels, free tissue factor pathway inhibitor (TFPI) antigen increased, whereas E-selectin decreased. In women with diabetes or elevated blood glucose >6.0 mmol/l, plasma homocysteine was correlated to body mass index, C-peptide and insulin as well as age.

CONCLUSION

Transdermal application of 17beta-estradiol and sequential MPA do not affect plasma homocysteine in women with established CAD. Plasma homocysteine is stable in women with CAD over time, and unless special intervention is undertaken, repetitive measurements are not necessary in this particular group of high-risk individuals. The circulating anticoagulant TEPI is related to plasma homocysteine.

Therapeutic effects of psyllium in type 2 diabetic patients

OBJECTIVE

The aim of this study was to evaluate the effects of psyllium in type 2 diabetic patients.

DESIGN

The study included three phases: phase 1 (1 week), phase 2 (treatment, 14 g fibre/day, 6 weeks) and phase 3 (4 weeks). At the end of each phase a clinical evaluation was performed after the ingestion of a test breakfast of 1824.2 kJ (436 kcal). Measurements included concentrations of blood glucose, insulin, fructosamine, GHbA(1c), C-peptide and 24 h urinary glucose excretion. In addition, uric acid, cholesterol and several mineral and vitamin concentrations were also evaluated.

SETTING

The study was performed at the Department of Pharmacology, Toxicology and Nursing at the University of León (Spain).

SUBJECTS

Twenty type 2 diabetic patients (12 men and 8 women) participated in the study with a mean age of 67.4 y for men and 66 y for women. The mean body mass index of men was 28.2 kg/m(2) and that of women 25.9 kg/m(2).

RESULTS

Glucose absorption decreased significantly in the presence of psyllium (12.2%); this reduction is not associated with an important change in insulin levels (5%). GHbA(1c), C-peptide and 24 h urinary glucose excretion decreased (3.8, 14.9 and 22.5%, respectively) during the treatment with fibre (no significant differences) as well as fructosamine (10.9%, significant differences). Psyllium also reduced total and LDL cholesterol (7.7 and 9.2%, respectively, significant differences), and uric acid (10%, significant difference). Minerals and vitamins did not show important changes, except sodium that increased significantly after psyllium administration.

CONCLUSIONS

The results obtained indicate a beneficial therapeutic effect of psyllium (Plantaben) in the metabolic control of type 2 diabetics as well as in lowering the risk of coronary heart disease. We also conclude that consumption of this fibre does not adversely affect either mineral or vitamin A and E concentrations. Finally, for a greater effectiveness, psyllium treatment should be individually evaluated.

Basal and postglucagon C-peptide levels in Ethiopians with diabetes

OBJECTIVE

To study basal C-peptide (BCP) and postglucagon C-peptide (PGCP) levels in Ethiopians with diabetes.

RESEARCH DESIGN AND METHODS

A total of 56 subjects with type 1 diabetes, 97 subjects with type 2 diabetes, and 50 control subjects were recruited from a hospital in Ethiopia. BCP was determined in all subjects and PGCP in 86 subjects.

RESULTS

Mean (+/- SEM) BCP, PGCP, and the increment after glucagon in type 1 diabetic subjects (0.14 +/- 0.04, 0.22 +/- 0.11, and 0.08 +/- 0.05 nmol/l, respectively) were lower (P < 0.001) than those in type 2 diabetic subjects (0.66 +/- 0.04, 1.25 +/- 0.10, and 0.56 +/- 0.06 nmol/l, respectively) or control subjects (0.54 +/- 0.04, 1.52 +/- 0.26, and 1.11 +/- 0.24 nmol/l, respectively). The mean BCP level was higher in type 2 diabetic subjects than control subjects (P=0.015), whereas the mean increment was lower (P=0.005). Insulin-treated type 2 diabetic subjects, compared with non-insulin-treated type 2 diabetic subjects, had lower mean BCP (0.55 +/- 0.08 nmol/l [n=37] vs. 0.73 +/- 0.04 [n=60], P=0.001), lower PGCP (0.97 +/- 0.20 nmol/l [n=18] vs. 1.40 +/- 0.11 [n=35], P=0.010), and a lower C-peptide increment (0.34 +/- 0.06 [n=18] vs. 0.67 +/- 0.07 nmol/l [n=35], P=0.003). In both the type 1 and type 2 diabetic groups, those with BCP levels <0.2 nmol/l had lower BMI than those with higher BCP levels (P=0.023 and P < 0.001, respectively).

CONCLUSIONS

Combined with clinical criteria, C-peptide levels are good discriminators between type 1 and type 2 diabetes in Ethiopians and may also be useful in identifying subjects with type 2 diabetes who require insulin therapy. There is a subgroup of type 2 diabetic subjects with features of type 1 diabetes.

Doxazosin reduces prevalence of small dense low density lipoprotein and remnant-like particle cholesterol levels in nondiabetic and diabetic hypertensive patients

Small dense low density lipoprotein (LDL) and remnant lipoproteins are potent atherogenic lipoproteins, often elevated in the plasma of patients with type 2 diabetes. The alpha1-blocker doxazosin has been reported to favorably affect the plasma lipid profile. We examined whether doxazosin could reduce these atherogenic lipoproteins in hypertensive subjects with and those without type 2 diabetes. Seventeen nondiabetic hypertensive patients and 33 hypertensive patients with type 2 diabetes were studied. Doxazosin (2 to 4 mg) was administered alone or with other previously received antihypertensive drugs for 6 months. Mean LDL size was measured by 2% approximately 16% gradient gel electrophoresis. Remnant-like particle (RLP)-cholesterol was measured with the use of an affinity column containing anti-apoA1 and B100 monoclonal antibodies. Doxazosin effectively decreased blood pressure (BP) without significantly affecting glucose, glycosylated hemoglobin (HbA1c), or C-peptide levels in both nondiabetic and diabetic patients. Doxazosin significantly reduced triglyceride, apo CIII, and apo B, but did not alter total-, LDL- or HDL-cholesterol. Mean LDL particle diameter was significantly increased from 25.6+/-0.6 nm to 25.9+/-0.4 nm (P < .001) by doxazosin treatment, regardless of the presence of diabetes. Consequently, the prevalence of small dense LDL (<25.5 nm) was halved in both groups. The increase in LDL size significantly correlated with decrease in triglyceride level (r=-0.798, P < .0001). Doxazosin significantly reduced RLP-cholesterol in both groups. These results suggest that doxazosin may help to prevent coronary artery disease by reducing atherogenic lipoproteins, including small dense LDL and remnant lipoproteins, in hypertensive patients, regardless of the presence of diabetes.

The impact of pioglitazone on glycemic control and atherogenic dyslipidemia in patients with type 2 diabetes mellitus

BACKGROUND

To evaluate the glycemic control, lipid effects, and safety of pioglitazone in patients with type 2 diabetes mellitus.

DESIGN AND METHODS

Patients (n = 197) with type 2 diabetes mellitus, a hemoglobin A1c (HbA1c) > or = 8.0%, fasting plasma glucose (FPG) > 7.7 mmol/l (140 mg/dl), and C-peptide > 0.331 nmol/l (1 ng/ml) were enrolled in this 23-week multi-center (27 sites), double-blind clinical trial and randomized to receive either a placebo or pioglitazone HCl 30 mg (pioglitazone), administered once daily, as monotherapy. Patients were required to discontinue all anti-diabetic medications 6 weeks before receiving study treatment. Efficacy parameters included HbA1c fasting plasma glucose (FPG), serum C-peptide, insulin, triglycerides (Tg), and cholesterol (total cholesterol [TC], high-density lipoprotein-cholesterol [HDL-C], low-density lipoprotein-cholesterol [LDL-C]). Adverse event rates, serum chemistry, and physical examinations were recorded.

RESULTS

Compared with placebo, pioglitazone significantly (P= 0.0001) reduced HbA1c (-1.37% points), FPG (-3.19 mmol/l; -57.5 mg/dl), fasting C-peptide (-0.076+/-0.022 nmol/l), and fasting insulin (-11.88+/-4.70 pmol/l). Pioglitazone significantly (P < 0.001) decreased insulin resistance (HOMA-IR; -12.4+/-7.46%) and improved beta-cell function (Homeostasis Model Assessment (HOMA-BCF); +47.7+/-11.58%). Compared with placebo, fasting serum Tg concentrations decreased (-16.6%; P = 0.0178) and HDL-C concentrations increased (+12.6%; P= 0.0065) with pioglitazone as monotherapy. Total cholesterol and LDL-C changes were not different from placebo. The overall adverse event profile of pioglitazone was similar to that of placebo, with no evidence of drug-induced elevations of serum alanine transaminase (ALT) concentrations or hepatotoxicity.

CONCLUSIONS

Pioglitazone improved insulin resistance and glycemic control, as well as Tg and HDL-C - which suggests that pioglitazone may reduce cardiovascular risk for patients with type 2 diabetes.

[Metabolic effects of berlipril-5 in patients with non-insulin dependent diabetes mellitus and arterial hypertension]

AIM

To study metabolic effects of berlipril-5 (enalapril) in patients with non-insulin-dependent diabetes mellitus (NIDDM) and arterial hypertension (AH).

MATERIALS AND METHODS

24 patients with NIDDM and AH were divided into three groups by the level of basal C-peptide: > 2 ng/ml (group 1), 2-4 ng/ml (group 2) and < 4 ng/ml (group 3).

RESULTS

A correlation was found between the level of basal C-peptide and duration of AH (r = 0.7) and NIDDM (r = -0.47), between the level of triglycerides (TG) and glycolized hemoglobin Hb A1c (r = 0.48). Berlipril treatment reduced basal C-peptide level in groups 2 and 3 by 20.65 +/- 1.95% and elevated it in group 1 by 16.4 +/- 1.5%. Fasting glucose levels lowered by 9.2 +/- 1.95% indicating better sensitivity of the liver to insulin. Blood glucose levels 2 hours after meal fell by 8.3 +/- 0.95% (p < 0.05) and Hb A1c by 8.14 +/- 1.25% showing indirectly diminishing insulin-resistance at the level of peripheral tissues. TG and VLDLP significantly declined.

CONCLUSION

Inhibitors of angiotensin converting enzyme (enalapril, in particular) produce a positive effect on carbohydrate and lipid metabolism in patients with NIDDM and AH.

Effect of human pancreastatin peptide (hP-16) on oral glucose tolerance in man

The gastrointestinal peptide, pancreastatin, has been shown to inhibit insulin release and exocrine pancreatic secretion in the rat. Human pancreastatin-like peptides first isolated from a carcinoid tumor, are expressed in human islets of Langerhans. To investigate the influence of human pancreastatin-16 (hP-16) on oral glucose tolerance (OGTT) in non-diabetic humans, we synthesized the C-terminally amidated human pancreastatin peptide. Healthy male volunteers (n = 6) received in a double-blind placebo-controlled study a 75 g standard OGTT during the i.v. infusion of hP-16 (10 pmol/kg/min) or saline over a time period of 3 h. Peak glucose levels (mg/dl) declined from 151.4 +/- 10.3 (control) to 122.5 +/- 9.7 (hP-16) (mean +/- SEM), peak insulin levels (microU/ml) from 46.3 +/- 2.9 (hP-16) to 32.2 +/- 4.0 (control) and peak C-peptide levels (pmol/ml) from 1.9 +/- 0.1 (hP-16) to 1.2 +/- 0.1 (control). Integrated incremental glucose, insulin and C-peptide responses were reduced by 47% (p < 0.001), 23% (p < 0.05) and 15% (p < 0.05), respectively. In conclusion, these findings indicate that hP-16 attenuates the elevation of blood glucose and insulin levels after an oral glucose load in non-diabetic humans.

The effect of acarbose on insulin sensitivity and proinsulin in overweight subjects with impaired glucose tolerance

Insulin sensitivity is impaired in overweight subjects with IGT and is accompanied by hyperinsulinemia, a condition, that might promote early B-cell exhaustion. Twelve subjects were recruited for a double-blind trial using either 100 mg of acarbose or placebo for three months. Insulin sensitivity was measured by hyperglycemic clamp and with the minimal model. Baseline characteristics such as body weight, BMI, blood glucose, HB-A1c and serum lipids did not change throughout the study period. The steady state glucose infusion rate (SSGIR) improved significantly following acarbose. The insulin sensitivity as measured by clamp (MI) or minimal model, (SI), however, increased only descriptively (p = 0.08). The fasting proinsulin was raised in all subjects during pretreatment. Following acarbose, the proinsulin dropped from 20.3 +/- 12.9 to 13.6 +/- 7.1 ng/ml, but remained unchanged in the placebo group. Due to the high variability of values and the low number of subjects in this study, differences were only descriptive and did not reach significance (p = 0.08). The proinsulin/insulin ratio, however, significantly decreased after 3 months of acarbose treatment. Acarbose might therefore be considered recommendable for the protection of the B-cell function and for delaying the transition of IGT to overt NIDDM.

Beginning insulin treatment of obese patients with evening 70/30 insulin plus glimepiride versus insulin alone. Glimepiride Combination Group

OBJECTIVE

This study tested a simple algorithm for beginning insulin for obese patients with type 2 diabetes after sulfonylurea failure, comparing suppertime 70/30 insulin plus continued glimepiride with insulin alone.

RESEARCH DESIGN AND METHODS

This was a multicenter ambulatory randomized double-masked parallel comparison. There were 208 subjects with secondary failure to sulfonylureas who took glimepiride titrated to 8 mg b.i.d. for 8 weeks; 145 subjects with fasting plasma glucose (FPG) 180-300 mg/dl (10-16.7 mmol/l) on this treatment were randomized to placebo plus insulin (PI) or glimepiride plus insulin (GI) for 24 weeks. A dosage of 70/30 insulin before supper was titrated, seeking fasting capillary blood glucose (FBG) 120 mg/dl (6.7 mmol/l), equivalent to FPG 140 mg/dl (7.8 mmol/l). Outcome measures included FPG, HbA1c, insulin dosage, weight, serum insulin and lipids, and adverse events.

RESULTS

FPG and HbA1c were equivalent at baseline: 261 vs. 250 mg/dl (14.5 vs. 13.9 mmol/l), and 9.9 vs. 9.7%. At 24 weeks, the FPG target was achieved in both groups (136 vs. 138 mg/dl, 7.6 vs. 7.6 mmol/l), and HbA1c values were equal (7.7 vs. 7.6%). However, with GI, control improved faster and fewer subjects dropped out (3 vs. 15%, P < 0.01), and less insulin was needed (49 vs. 78 U/d, P < 0.001). The outcomes were alike in other respects. No subject had severe hypoglycemia.

CONCLUSIONS

Injection of 70/30 insulin before supper safely restored glycemic control of type 2 diabetes not controlled by glimepiride alone. Control was restored more rapidly and with less injected insulin when glimepiride was continued.

Overnight GLP-1 normalizes fasting but not daytime plasma glucose levels in NIDDM patients

GLP-1 (7-36 amide) normalizes fasting plasma glucose in NIDDM patients. It was the aim to study the effect of overnight intravenous GLP-1 (7-36 amide) on the following 24 h-glucose profiles. Ten NIDDM patients (7 female, 3 male; age 62 +/- 4 y., BMI (Body-Mass-Index) 29.6 +/- 3.9 kg/m2, duration 10 +/- 7 y., HbA1c 10.9 +/- 1.3% (normal 4.0-6.1%), treated with glibenclamide and/or metformin) were studied on two occasions in random order: Either GLP-1 (7-36 amide) (Saxon Biochemicals, Hannover, FRG, 1 pmol x kg(-1) x min(-1)) or placebo (0.9% NaCl with 1% human serum albumin, Behringwerke, Marburg, FRG) were infused intravenously from 22:00 to 7:00 (9 h) and plasma glucose profiles were obtained during the GLP-1 infusion and the following 24 hours. GLP-1 (7-36 amide) (plasma concentration 110 +/- 12 pmol/l) raised plasma C-peptide concentrations (p = 0.0005), suppressed glucagon (p = 0.01) and lowered plasma glucose to 5.5 +/- 0.6 and 6.3 +/- 0.4 mmol/l at 3:00 and 7:00 a.m. (vs. 10.3 +/- 0.9 and 11.3 +/- 0.6 mmol/l, p = 0.0003 and p < 0.0001, respectively, with placebo). Thereafter, starting 1 h after breakfast, no significant differences in plasma glucose, insulin, C-peptide or glucagon profiles were found between experiments with GLP-1 (7-36 amide) and placebo. Average plasma glucose concentrations over the whole 24 h period were reduced by 18% by GLP-1 administered overnight. In conclusion, (1) overnight GLP-1 (7-36 amide) normalizes fasting plasma glucose, but (2) has no sustained effect on meal-induced glucose, insulin or glucagon concentrations once its administration has been stopped. (3) Normalization of fasting plasma glucose alone does not improve daytime metabolic control in NIDDM patients on oral agents.

Changes in amylin and amylin-like peptide concentrations and beta-cell function in response to sulfonylurea or insulin therapy in NIDDM

OBJECTIVE

Amylin, a secretory peptide of beta-cells, is the constituent peptide of islet amyloid, which is characteristic of NIDDM, and changes in amylin secretion in response to therapies may influence the rate of production of islet amyloid. The primary objective of this study was to determine whether therapy with sulfonylurea or basal insulin in NIDDM would alter amylin secretion in a way that might affect the formation of islet amyloid.

RESEARCH DESIGN AND METHODS

In a randomized crossover design, eight subjects with NIDDM underwent three 8-week periods of therapy with diet alone, sulfonylurea, or exogenous basal insulin, with evaluation of amylin, amylin-like peptide (ALP), and glucose and C-peptide concentrations, both during fasting and after a standard breakfast. Changes in beta-cell function (% beta) were assessed, in the basal state by homeostasis model assessment (HOMA) and in the stimulated state by hyperglycemic clamps. Seven nondiabetic control subjects each underwent a meal profile and hyperglycemic clamp.

RESULTS

Both sulfonylurea and insulin therapy reduced basal glucose concentrations compared with diet alone, but neither reduced the increased postprandial glucose increments. Both sulfonylurea and insulin therapy increased basal % beta, assessed by HOMA, but only sulfonylurea increased the second-phase C-peptide responses to the hyperglycemic clamp. Sulfonylurea increased time-averaged mean postprandial amylin and ALP concentrations compared with diet alone (geometric mean [1-SD range] for amylin, 4.9 [2.0-11.8] vs. 3.0 [1.4-6.2] pmol/l, P = 0.003; for ALP, 16.4 [8.5-31.7] vs. 10.1 [4.9-20.8] pmol/l, P = 0.001). Insulin therapy reduced basal ALP concentrations compared with diet alone (2.9 [1.5-5.6] vs. 6.0 [2.6-13.6] pmol/l, P = 0.03), but had no effect on postprandial concentrations of amylin (3.0 [1.3-6.5] pmol/l) or ALP (10.0 [5.5-18.1] pmol/l).

CONCLUSIONS

By increasing postprandial concentrations of the constituent peptides of islet amyloid, sulfonylurea therapy might increase the rate of deposition of islet amyloid and thereby accelerate the decline of % beta in NIDDM, compared with diet therapy alone.

The effects of coenzyme Q10 treatment on maternally inherited diabetes mellitus and deafness, and mitochondrial DNA 3243 (A to G) mutation

The characteristic clinical features of diabetes mellitus with mitochondrial DNA (mtDNA) 3243(A-G) mutation are progressive insulin secretory defect, neurosensory deafness and maternal inheritance, referred to as maternally inherited diabetes mellitus and deafness (MIDD). A treatment for MIDD to improve insulin secretory defects and reduce deafness has not been established. The effects of coenzyme Q10 (CoQ10) treatment on insulin secretory response, hearing capacity and clinical symptoms of MIDD were investigated. 28 MIDD patients (CoQ10-DM), 7 mutant subjects with impaired glucose tolerance (IGT), and 15 mutant subjects with normal glucose tolerance (NGT) were treated daily with oral administration of 150 mg of CoQ10 for 3 years. Insulin secretory response, blood lactate after exercise, hearing capacity and other laboratory examinations were investigated every year. In the same way we evaluated 16 MIDD patients (control-DM), 5 mutant IGT and 5 mutant NGT subjects in yearly examinations. The insulin secretory response assessed by glucagon-induced C-peptide secretion and 24 h urinary C-peptide excretion after 3 years in the CoQ10-DM group was significantly higher than that in the control-DM group. CoQ10 therapy prevented progressive hearing loss and improved blood lactate after exercise in the MIDD patients. CoQ10 treatment did not affect the diabetic complications or other clinical symptoms of MIDD patients. CoQ10 treatment did not affect the insulin secretory capacity of the mutant IGT and NGT subjects. There were no side effects during therapy. This is the first report demonstrating the therapeutic usefulness of CoQ10 on MIDD.

Induction of beta-cell rest in type 1 diabetes. Studies on the effects of octreotide and diazoxide

OBJECTIVE

To evaluate the inhibitory effects of octreotide and diazoxide on insulin secretion in patients with type 1 diabetes and measurable levels of circulating C-peptide.

RESEARCH DESIGN AND METHODS

Diazoxide was given to six patients during a 7-day period (100 mg three times daily), followed by a 3-week washout. Subsequently, octreotide (50 micrograms, three times daily) was administered subcutaneously for 7 days. Pre- and post- prandial blood glucose and serum C-peptide concentrations were measured before medication (control) and on day 7 of each medication period. Glucagon-stimulated C-peptide was determined in the morning before medication and on the day after each treatment period.

RESULTS

Diazoxide inhibited glucagon-stimulated C-peptide secretion (mean increment 0.08 nmol/l vs. 0.18 nmol/l, P < 0.05), whereas octreotide had no such effect. Both reduced the pre- and postprandial serum C-peptide concentrations (P < 0.05), octreotide being the more potent in this respect. A reduction in basal and meal-related blood glucose was observed during octreotide treatment, whereas the glucose concentrations tended to be higher during treatment with diazoxide than during the 24-h control period.

CONCLUSIONS

The study indicates that the two drugs reduce insulin output by different mechanisms. Diazoxide inhibits hormonal release directly on the beta-cells, whereas octreotide exerts its effect indirectly, presumably by multiple actions on insulin sensitivity and insulin-releasing hormones. The results suggest that each drug is capable of inducing beta-cell rest in type 1 diabetes.

The effect of transdermal 17-beta-estradiol on glucose metabolism of postmenopausal women is evident during the oral but not the intravenous glucose administration

OBJECTIVES

To evaluate the effect of transdermal 17-beta-estradiol (50 micrograms/day) on glucose metabolism of postmenopausal women.

STUDY DESIGN

A frequently sampled intravenous glucose tolerance test (FSIGT), to calculate insulin sensitivity (SI) and peripheral glucose utilization independent of insulin (SG), and an oral glucose tolerance test (75 g; OGTT), were performed in nine postmenopausal women prior to, and after 2 months of, treatment.

RESULTS

Estradiol decreased insulin and increased the C-peptide/insulin ratio both during fasting (P < 0.02) and OGTT (insulin levels, P < 0.01; C-peptide/insulin ratio, P < 0.05), but not FSIGT. Glucose levels, C-peptide levels, SI and SG were not affected.

CONCLUSIONS

In spite of unmodified SI, the reduction of insulin levels and the increase of the C-peptide/insulin ratio, observed during fasting and OGTT, support a beneficial effect of estradiol on glucose metabolism. This effect probably requires the interplay of estradiol with gastrointestinal factors.

The mode of action of prostaglandin (PG) I1 analog, SM-10906, on fibroblasts of hypertrophic scars is similar to PGE1 in its potential role of preventing scar formation

The effects of prostaglandin (PG) I1 analog, SM-10906 (SM-6) and PGE1 on extracellular matrix formation and the release of cytokines by cultured normal human dermal fibroblasts (NDF) and hypertrophic scar fibroblasts (HSF) were compared in order to evaluate the clinical efficacy of PGs in preventing scar formation. In the present study, we measured type I collagen synthesis, collagenase activity, production of interleukin (IL)-6, IL-8, and transforming growth factor (TGF)-beta 1 and levels of adenosine 3,5-cyclic monophosphate (cAMP) in NDF and HSF cultured with or without PGs. The results demonstrated that HSF culture supernatants has a significantly higher level of type I collagen and TGF-beta 1 than those of NDF. However, the levels of collagenase activity and IL-8 in HSF were significantly lower in comparison to that of NDF. There was no substantial difference in IL-6 production between two types of culture cells. On the other hand, PGE1 and SM-6 significantly enhanced collagenase activity and raised the collagenase/type I collagen ratio in the HSF supernatants. In addition, both PGE1 and SM-6 increased production of TGF-beta 1, IL-8 and IL-6 and levels of cAMP in both cell types. However, they had no effect on the type I collagen synthesis of either types. These results suggest that, the stable PGI1 analog, SM-6, similarly acts as PGE1 in HSF by increasing the activity of collagenase.

Effects of octreotide on glycaemic control, glucose disposal, hepatic glucose production and counterregulatory hormones secretion in type 1 and type 2 insulin treated diabetic patients

We studied the effects of continuous subcutaneous infusion of octreotide (100 micrograms/day for 5 days) on glycaemic values, counterregulatory hormones secretion, hepatic glucose production (HGP) and glucose disposal during an euglycaemic clamp in 7 C-peptide-negative type 1 diabetic patients and 7 C-peptide positive insulin-treated type 2 diabetic patients. In type 1, but not type 2 diabetic patients, octreotide significantly reduced glycaemic values (P < 0.005) and also diminished HGP during an euglycaemic clamp (P < 0.05). However, insulin stimulated global glucose uptake remained unchanged. GH, glucagon, IGF-I, IGFBP-3 levels, were significantly lowered by octreotide in both type 1 and type 2 diabetic patients whereas cortisol and epinephrine remained unmodified. Moreover in type 2 diabetic patients both basal (P < 0.05) and after-meal (P < 0.01) C-peptide secretion was reduced by octreotide. These data point to different metabolic effects of octreotide in type 1 versus type 2 diabetic patients with the drug only being able to reduce glycaemic values and HGP in the former but not in the latter subjects. The failure of octreotide to diminish glycaemic values and HGP in type 2 diabetic patients in spite of its ability to lower GH and glucagon may probably depend on temporary blockage of residual endogenous insulin secretion induced by octreotide administration.

Influence of chronic Naltrexone treatment on growth hormone and insulin secretion in obese subjects

OBJECTIVE

Recent studies have demonstrated the restoration of a normal 24 h GH profile induced by a reduction of insulinaemia after weight loss, suggesting a reciprocal relationship between plasma insulin and GH concentrations. We aimed to clarify if an opiate-induced reduction in plasma insulin could affect GH secretion in obesity.

DESIGN

We have studied the insulin response to an oral glucose tolerance test (OGTT) and the GH response to GHRH before and after prolonged treatment with Naltrexone (NTX). C-peptide, IGF-I, IGFBP-3 plasma levels and the IGF-I/IGFBP-3 molar ratio were also determined.

SUBJECTS

Twelve obese women (aged 25-41 y; Body mass index (BMI): 31-39 kg/m2) and six lean normal women (aged 25-38; BMI: 19.8-23.1 kg/m2).

MEASUREMENT

GH was determined by the IRMA method; insulin, C-peptide, IGF-I and IGFBP-3 were assayed by the RIA method. For molar comparison between IGF-I and IGFBP-3 we have considered 30.5 kDa the molar weight of IGFBP-3. Results are expressed as mean +/- s.e.m.

RESULTS

We observed a significant decrease in basal concentration of both insulin (230.1 +/- 34.9 vs 133.2 +/- 16.9 pmol/L; P < 0.005) and C-peptide (3.7 +/- 0.3 vs 2.4 +/- 0.1 micrograms/L; P < 0.02). No modifications in the insulin secretory response to the OGTT were observed. A significant increase of the GHRH-induced GH peak response (7.7 +/- 1.4 vs 19.7 +/- 3.1 micrograms/L; P < 0.01) and GH-AUC (533 +/- 151 vs 1415 +/- 339 micrograms/L/120 min; P < 0.01) was found after NTX treatment. A negative correlation was found between basal insulin and GH peak values, both before (r = -0.641, P = 0.027) and after NTX (r = -0.714, P = 0.013). No modifications were found in IGF-I, IGFBP-3 and IGF-I/IGFBP-3 molar ratio. Moreover, NTX affected neither the insulin response to OGTT or IGF-I, IGFBP-3 and IGF-I/IGFBP-3 molar ratio in a group of six lean controls. Conversely, NTX significantly reduced the GH response to GHRH, when expressed as both peak and AUC values.

CONCLUSIONS

The opiate antagonist significantly reduced basal insulin concentrations and augmented the GH response to GHRH in obese subjects. In the absence of modifications in IGF-I and IGFBP-3 plasma levels and their molar ratio, we propose that insulin may exert a negative feedback on GH secretion.

Good metabolic and safety profile of troglitazone alone and following alcohol in NIDDM subjects

Drinking alcohol is associated with a recognised risk of hypoglycaemia. This double-blind, placebo-controlled study was designed to determine whether alcohol taken with the evening meal alters the gluco-regulatory response to troglitazone, (TR), an insulin action enhancer, in non-insulin-dependent diabetes mellitus (NIDDM) subjects to increase the risk of hypoglycaemia. In vitro studies conducted prior to the clinical study presented here showed no evidence of a pharmacokinetic interaction between the two drugs. A total of 23, diet-treated, NIDDM subjects received either TR, 200 mg once daily (n = 11) or placebo (PL) (n = 12) for 45 days. On days 42 and 45 subjects were given, on separate days, an alcohol challenge (AC), 0.6 mg/kg ethanol in orange juice and a control challenge, CC, orange juice alone, with the evening meal. Serum glucose, insulin, proinsulin-like molecules, C-peptide and lipids were measured during the study, for the 4 h after each challenge and the following morning (fasting). The over-night urine cortisol/creatinine ratio (an index of hypoglycaemia) was also determined. For the TR treated group, fasting serum glucose the next morning (adjusted geometric mean: 6.8 mmol/l for AC) and weighted mean were not statistically significantly different following AC compared to CC. Mean trough glucose for TR after the evening meal was 5.7 mmol/l following both the AC and CC. Analysis of the other parameters showed no symptomatic or pharmacodynamic evidence of an acute interaction between TR and alcohol. It can be concluded that occasional drinking of alcohol, with a meal, by TR-treated NIDDM patients is unlikely to be associated with an increased risk of hypoglycaemia.

Induction of long-term glycemic control in newly diagnosed type 2 diabetic patients by transient intensive insulin treatment

OBJECTIVE

Type 2 diabetes is a slowly progressive disease, in which the gradual deterioration of glucose tolerance is associated with the progressive decrease in beta-cell function. Hyperglycemia per se has deleterious effects on both beta-cell function and insulin action, which are partially reversible by the short-term control of blood glucose levels. We hypothesized that the induction of euglycemia, using intensive insulin therapy at the time of clinical diagnosis, could lead to a significant improvement in insulin secretion and action and thus alter the clinical course of the disease.

RESEARCH DESIGN AND METHODS

Thirteen newly diagnosed diet-unresponsive type 2 diabetic patients were treated with continuous subcutaneous insulin infusion (CSII) for 2 weeks and followed longitudinally while being treated with diet alone.

RESULTS

Four patients were considered therapeutic failures since CSII failed to induce euglycemia (n = 1) or glucose control deteriorated within 6 months after CSII (n = 3). The remaining nine patients were maintained on diet alone with adequate control from 9 to > 50 months (median +/- SE, 26 +/- 4.8 months). In five patients, glycemic control deteriorated after 9-36 months, but a repeat 2-week CSII treatment reestablished control in four patients. One of these patients underwent a third CSII treatment 13 months later. At the time this article was written, six patients of the initial group were still controlled without medication 16-59 months (median +/- SE, 45.5 +/- 6.6 months) after the initiation of treatment. Body weight remained unchanged in all patients.

CONCLUSIONS

These findings suggest that in a significant proportion of type 2 diabetic patients who fail to respond to dietary measures, short-term intensive insulin treatment can effectively establish responsiveness, allowing long-term glycemic control without medication. Further studies are required to establish whether simpler treatment regimens could be equally effective. If the hypothesis offered here finds support, present approaches to the management of newly diagnosed type 2 diabetes may need to be revised.