Non-fasting Blood Glucose Concentrations Research Articles

Elevations in blood glucose before and after the appearance of islet autoantibodies in children.

The etiology of type 1 diabetes has polygenic and environmental determinants that lead to autoimmune responses against pancreatic β cells and promote β cell death. The autoimmunity is considered silent without metabolic consequences until late preclinical stages,and it remains unknown how early in the disease process the pancreatic β cell is compromised. To address this, we investigated preprandial nonfasting and postprandial blood glucose concentrations and islet autoantibody development in 1,050 children with high genetic risk of type 1 diabetes. Pre- and postprandial blood glucose decreased between 4 and 18 months of age and gradually increased until the final measurements at 3.6 years of age. Determinants of blood glucose trajectories in the first year of life included sex, body mass index, glucose-related genetic risk scores, and the type 1 diabetes–susceptible INS gene. Children who developed islet autoantibodies had early elevations in blood glucose concentrations. A sharp and sustained rise in postprandial blood glucose was observed at around 2 months prior to autoantibody seroconversion, with further increases in postprandial and, subsequently, preprandial values after seroconversion. These findings show heterogeneity in blood glucose control in infancy and early childhood and suggest that islet autoimmunity is concurrent or subsequent to insults on the pancreatic islets.

Empagliflozin ameliorates symptoms of diabetes and renal tubular dysfunction in a rat model of diabetes with enlarged kidney (DEK).

BackgroundSodium-glucose cotransporter 2 (SGLT2) inhibitors are widely used to reduce hyperglycemia. The present study investigated the effects of a SGLT2 inhibitor, empagliflozin, on hyperglycemia in a novel rat model of non-obesity type 2 diabetes with enlarged kidney (DEK).MethodsMale DEK rats with non-fasting blood glucose concentrations ≤300 mg/dl and >300 mg/dl were classified as nondiabetic and diabetic, respectively. Groups of nondiabetic (control) and diabetic (DM-cont) rats were fed standard chow for 12 weeks, whereas another group of diabetic (DM-empa) rats was fed standard chow containing empagliflozin (300 mg/kg/day) for 12 weeks. Blood glucose, body weight, glucose tolerance, food and water intake, urinary volume, plasma and urinary biochemical parameters, and bone mineral density were measured, and their kidneys and pancreas histologically analyzed.ResultsTreatment with empagliflozin reduced blood glucose concentration and food intake in diabetic rats, but inhibited loss of adeps renis and led to body weight gain. Empagliflozin attenuated polyuria and polydipsia but increased plasma concentrations of total cholesterol, sodium and total protein toward normal level. Empagliflozin also significantly reduced urinary excretion of proteins and electrolytes and restored bone mineral density and plasma concentrations of valine and isoleucine to normal levels. Moreover, dilation of renal tubules and kidney enlargement were not attenuated in the DM-empa group.ConclusionThe response of DEK rats to empagliflozin differed from that of other diabetic animal models, suggesting that DEK rats have unique characters for studying and evaluating the multiple biological effects of SGLT2 inhibitors. These findings also indicted that empagliflozin could ameliorate systemic metabolism and improve renal tubule function in diabetic condition.

Discovery of a novel fibroblast activation protein (FAP) inhibitor, BR103354, with anti-diabetic and anti-steatotic effects

Fibroblast growth factor (FGF) 21 is a class of hepatokines that plays a protective role against obesity, insulin resistance, and liver damage. Despite this, protective effects of FGF21 in human appear to be minimal, possibly due to its proteolytic cleavage by the fibroblast activation protein (FAP). Here, we presented a novel FAP inhibitor, BR103354, and described its pharmacological activities as a potential therapeutic agent for the treatment of metabolic disorders. BR103354 inhibited FAP with an IC50 value of 14 nM, showing high selectivity against dipeptidyl peptidase (DPP)-related enzymes and prolyl oligopeptidase (PREP). In differentiated 3T3/L1 adipocytes, the addition of FAP diminished hFGF21-induced Glut1 and phosphorylated levels of ERK, which were restored by BR103354. BR103354 exhibited good pharmacokinetic properties as evidenced by oral bioavailability of 48.4% and minimal hERG inhibition. Single co-administration of BR103354 with hFGF21 reduced nonfasting blood glucose concentrations, in association with increased intact form of hFGF21 in ob/ob mice. Additionally, chronic treatment of BR103354 for 4 weeks reduced nonfasting blood glucose concentrations with improved glucose tolerance and with reduced triglyceride (TG) content in liver of ob/ob mice. Consistently, BR103354 improved hepatic steatosis and fibrosis in a choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD)-induced non-alcoholic steatohepatitis (NASH) mouse model. FAP inhibitory effects of BR103354 were confirmed in normal cynomolgus monkeys. Together, BR103354 acts as an effective FAP inhibitor in vitro and in vivo, thereby demonstrating its potential application as an anti-diabetic and anti-NASH agent.

Adipose Tissue From Type 1 Diabetes Mellitus Patients Can Be Used to Generate Insulin-Producing Cells.

We aimed to determine whether responsive insulin-producing cells (IPCs) could be generated from adipose-derived stem cells (ADSCs) isolated from patients with type 1 diabetes mellitus (T1DM). We isolated ADSCs from adipose tissue of 4 patients (one patient with T1DM and 3 nondiabetic patients), who underwent surgery and differentiated them into IPCs with using a 2-step xeno-antigen free, 3-dimensional culture method. Characteristics of isolated ADSCs, in vitro cell quality, programmed cell death ligand-1 (PDL-1) expression, and transplantation into streptozotocin induced diabetic nude mice were investigated. Adipose-derived stem cells from T1DM patients and commercially obtained ADSCs showed the same surface markers; CD31CD34CD45CD90CD105CD146. Moreover, the generated IPCs at day 21 demonstrated appropriate autonomous insulin secretion (stimulation index, 3.5; standard deviation, 0.8). Nonfasting blood glucose concentrations of IPC-transplanted mice were normal at 30 days. The normalized rate of IPC-transplanted mice was significantly higher than that of the sham-operated group (P < 0.05). Insulin-producing cells generated from T1DM adipose tissue expressed high levels of PDL-1. Insulin-producing cells obtained from adipose tissue of T1DM patients are capable of secreting insulin long-term and achieve normoglycemia after transplantation. Expression of PDL-1 suggests the potential for immune circumvention.

The generation of effective insulin-producing cells from ADSC derived from type 1 diabetes mellitus patients

Background & Aim We have reported the possibility of non-clinical PoC for generating insulin-producing cells (IPCs) differentiated from adipose-derived stem cells (ADSCs). However, whether ADSC isolated from type 1 diabetes mellitus (T1DM) patients has the differentiation ability or not is still unclear. Thus, we aimed to determine whether appropriately responsive IPCs could be generated from ADSCs isolated from actual T1DM patients. Methods, Results & Conclusion Methods We isolated ADSCs from the discarded adipose tissue from four patients undergoing surgery at our institute and differentiated them into IPCs using our established two-step xeno-antigen free, three-dimensional culture method (UMI35546,IRB approved on Jan 10, 2018). Characters of isolated ADSCs, in vitro cell quality and cell function, programmed cell death ligand-1(PDL-1) expression and in vivo functional tests by transplantation to streptozotocin (STZ) induced diabetic nude mice were investigated. Results ADSCs from T1DM patients and commercially obtained ADSCs showed the same surface markers; CD31−CD34−CD45−CD90+CD105+CD146−. Moreover, the generated IPCs at day 21 demonstrated appropriate autonomous insulin secretion in vitro (stimulation index;3.5). The non-fasting blood glucose concentrations of STZ-induced diabetic nude mice were normal 30 days after IPC transplantation. The normalized rate of STZ-induced diabetic nude mice was significantly different to the sham-operated group (P Conclusions These findings suggest that IPCs obtained from the adipose tissue of T1DM patients are capable of secreting insulin long-term and achieving normoglycemia following a single auto-transplantation, and without the need for immunosuppression.

Glucagon from the phylogenetically ancient paddlefish provides a template for the design of a long-acting peptide with effective anti-diabetic and anti-obesity activities

This study has examined the in vitro and in vivo anti-diabetic properties of the peptidase-resistant analogues [D-Ser2]palmitoyl-paddlefish glucagon and [D-Ser2]palmitoyl-lamprey glucagon. The peptides stimulated insulin release from BRIN-BD11 clonal β-cells and isolated mouse pancreatic islets and also enhanced cAMP production in cells transfected with the human GLP-1 receptor and with the human glucagon receptor. The insulinotropic actions of the peptides were attenuated in INS-1 cells lacking GLP-1 and glucagon receptors. [D-Ser2]palmitoyl-paddlefish glucagon stimulated proliferation of BRIN-BD11 cells and protected against cytokine-mediated apoptosis as effectively as GLP-1. The analogue was more effective than the native peptide or the lamprey glucagon analogue in acutely lowering blood glucose and elevating plasma insulin in lean mice even when administered up to 4 h before a glucose load. Twice daily administration of [D-Ser2]palmitoyl-paddlefish glucagon to high-fat fed mice over 21 days reduced food intake, body weight, non-fasting blood glucose and plasma insulin concentrations, as well as significantly improving glucose tolerance and insulin resistance and decreasing α-cell area and pancreatic insulin content. Islet expression of the Gcgr, Glp1r, Gipr and Slc2a2 (GLUT-2) genes significantly increased. These data demonstrate that long-acting peptide [D-Ser2]palmitoyl-paddlefish glucagon exerts beneficial metabolic properties in diabetic mice via Ggcr- and Glp1r-activated pathways and so shows potential as a template for further development into an agent for treatment of patients with obesity-related Type 2 diabetes.

Preparation and evaluation of lactic acid acylated exenatide and its long-acting preparation

Exenatide (EX), a glucagon-like peptide-1 receptor agonist, is used to treat diabetes mellitus. However, its short half-life necessitates frequent administration and fluctuations in its plasma concentration may cause adverse effects. Previously, we developed glycolic acid acylated EX, which showed a good glucose-lowering effect. However, the release of lactic acid (LA) acylated exenatide (LA-EX) as an acylated adduct in EX microspheres has not been studied. Here, we investigated the biological properties of LA-EX. Additionally, LA-EX-loaded microspheres were formulated by an emulsion–solvent evaporation method and their in vitro characteristics, in vivo pharmacokinetic properties, and antidiabetic activities were evaluated. Pharmacokinetic studies revealed that the t1/2 of LA-EX (5.95 h) was 2.3-fold longer than that of EX. The antidiabetic activities of LA-EX in db/db mice were similar to those of EX. LA-EX release from microspheres was fairly well-sustained compared to that of EX microspheres. Additionally, LA-EX-loaded microspheres were more effective in lowering nonfasting blood glucose concentrations than EX microspheres. These findings suggest that LA-EX have the same efficacy as EX and that encapsulating LA-EX into microspheres can achieve better efficacy for the long-term type 2 diabetes mellitus treatment.

Screening for Diabetes Mellitus and Gestational Diabetes in a Resource-Poor Setting—Implementing a Selective Protocol

Background: Screening for diabetes mellitus and gestational diabetes in resource-poor settings requires efficiency. To make the best use of resources, we proposed a selective diabetes screening protocol for patients in rural Panama as a cost-effective solution for diabetes screening in resource-limited settings. We proposed to screen adults aged 35 years or above and pregnant women of all ages. Methods: Patients that attended a three-day clinic in Bocas del Toro, Panama established by the non-for-profit organization Floating Doctors were screened for non-fasting blood glucose levels. The proposed selective diabetes screening protocol was applied to determine whether it identified patients that were diabetic or prediabetic. Criteria for diabetes and prediabetes were based on existing American Diabetes Association guidelines: patients with a non-fasting blood glucose concentration of ≥200 mg/dl were considered diabetic and patients with a non-fasting blood glucose concentration of ≥140 mg/dl but &amp;lt; 200 mg/dl were considered prediabetic. Results: Of 84 patients that attended clinic, 2 were diabetic (2.3%) and 55 were prediabetic (65.5%). The sub-group of 41 patients (48.8%) met the selective screening protocol criteria of being at or above the age of 35 years and/or pregnant. This group included 2 patients that screened positive for diabetes (4.9%) and consisted of 16 patients with prediabetes (39.0%). The group excluded by the proposed protocol (51.2%) consisted of no patients with diabetes and 17 with prediabetes (39.5%). Conclusion: The proposed selective diabetes screening protocol effectively identified all patients with diabetes but only about half the patients with prediabetes, suggesting this protocol may have utility in diagnosing diabetes for treatment purposes. However, because a significant number of prediabetic individuals were excluded, other strategies are necessary for preventative efforts. Disclosure K.A. Cabrera: None. A. Pendi: None. N. Lashkari: None. E. El-Tobgy: None. B.B. LaBrot: None.

Low-dose Insulin Treatment Ameliorate Glucose Metabolism in Type 1 Diabetic Rats

Study background: Type 1 diabetes is an insulin-dependent diabetes mellitus (IDDM) because the body does not produce sufficient insulin for daily need. Persistent high glucose level in the blood circulation can stimulate the advanced glycation end products/receptor for AGEs (AGE/RAGE) pathway leading to diabetic complications. Currently, there is no preventive measure for IDMM with only treatment focusing on delaying the onset of diabetic complications. This study aimed to investigate how the different insulin regimens given affect the glycemic control and glucose metabolism in type 1 diabetes. The effects on the AGE/RAGE axis were determined as well. Methods: Twenty-one male Sprague-Dawley rats were randomly assigned into three groups (Group A: streptozotocin-induced diabetic rats given high-dose insulin [5-7U per day], Group B: streptozotocin-induced diabetic rats given low-dose insulin [0-3U per day], Group C: non-diabetic control). Throughout the eight-week treatment, the body weight, systolic blood pressure and non-fasting blood glucose concentration were monitored. After eight weeks of treatment, fasting blood glucose concentration, glycated haemoglobin (HbA1c), nuclear factor kappa B (NF-κB), AGE level and RAGE expression were measured. Results: High-dose insulin treatment impaired glucose metabolism. On the contrary, diabetic rats receiving lowdose insulin showed reduced glucose level and improved insulin sensitivity towards the end of experiment. HbA1c level was significantly lower in low-dose insulin treated rats while NF-κB level was significantly lower in high-dose insulin treated rats (p ≤ 0.05). There was no significant difference in AGE levels in all the groups (p>0.05) and only the heart tissues from the low-dose insulin treated group showed significant down regulation of the RAGE gene expression (p ≤ 0.05). Conclusion: Low-dose insulin treatment was shown to be a better therapeutic intervention for type 1 diabetes.

Anti-diabetic effects of the acetone fraction of Senna singueana stem bark in a type 2 diabetes rat model

Ethnopharmacological relevanceSenna singueana is currently used in the traditional treatment of diabetes mellitus in Nigeria. The present study examined the anti-diabetic activity of the Senna singueana acetone fraction (SSAF) of stem bark in a type 2 diabetes (T2D) rat model. Materials and methodsCrude ethyl acetate extract of the Senna singueana stem bark was fractionated with various solvents and the acetone fraction was selected for in vivo studies based on the high α-glucosidase and α-amylase inhibitory activities. In the in vivo study, male Sprague-Dawley rats were induced with T2D and treated with the SSAF at 150 and 300mg/kg body weight. Several T2D-related parameters were measured in the study. ResultsAfter 4 weeks of intervention, non-fasting blood glucose concentrations were significantly decreased and the glucose tolerance ability was significantly improved in the SSAF treated groups compared to the diabetic control group. Serum insulin concentrations, pancreatic β-cell function (HOMA-β) and liver glycogen were significantly (P<0.05) increased while serum alanine transaminase, alkaline phosphatase and urea were significantly decreased in the SSAF treated diabetic rats compared to the diabetic control group. Though insignificantly (P>0.05), other T2D-induced abnormalities such as food and fluid intake, body weight, serum lipids, serum fructosamine level and peripheral insulin resistance (HOMA-IR) were also partially ameliorated by the SSAF treatment. ConclusionData of this study suggest that orally administered SSAF could ameliorate most of the T2D-induced abnormalities in a T2D model of rats.

Islet Transplantation in a Subarachnoid Cavity Surrounding Olfactory Bulb of Diabetic Rats

Islet Transplantation in a Subarachnoid Cavity Surrounding Olfactory Bulb of Diabetic Rats

The future of preventive medicine: Polypill prescriptions in the context of Plato's physical perspective

The objective was to determine whether non-fasting glucose concentration is a predictor for incident coronary heart disease.We investigated a cohort data of 9,900 40- to 69-year-old residents in four Japanese communities for 1975–1986 baseline surveys of the Circulatory Risk in Communities Study (CIRCS). Non-fasting blood glucose concentrations were available for 7,332 participants. Diabetic type was defined as a glucose level of ≥ 11.1 mmol/L and/or the use of medication for diabetes mellitus.A total of 170 coronary heart disease including 113 myocardial infarctions occurred in non-fasting participants within the median 22-year follow-up period. Multivariable hazard ratios (HRs) of incident coronary heart disease for the participants with diabetic type compared with the normal type were 1.98 (0.84–4.68) for men, 3.39 (1.47–7.81) for women, and 2.47 (1.37–4.46) for total subjects. Corresponding HRs for myocardial infarction were 2.14 (0.83–5.55), 5.70 (2.21–14.67) and 3.17 (1.65–6.10), respectively. Multivariable HRs of incident coronary heart disease per one standard deviation of serum glucose levels were 1.17 (1.02–1.36), 1.19 (1.03–1.38), and 1.19 (1.08–1.32), respectively. The corresponding HRs for myocardial infarction were 1.18 (1.00–1.38), 1.27 (1.07–1.49) and 1.23 (1.10–1.37).Non-fasting glucose concentration, either as diagnosis of diabetic type or as continuous variable, proved to be an independent predictor for incident coronary heart disease in middle-aged general population.

Non-fasting blood glucose and risk of incident coronary heart disease in middle-aged general population: The Circulatory Risk in Communities Study (CIRCS)

ObjectiveThe objective was to determine whether non-fasting glucose concentration is a predictor for incident coronary heart disease. MethodsWe investigated a cohort data of 9,900 40- to 69-year-old residents in four Japanese communities for 1975–1986 baseline surveys of the Circulatory Risk in Communities Study (CIRCS). Non-fasting blood glucose concentrations were available for 7,332 participants. Diabetic type was defined as a glucose level of ≥11.1mmol/L and/or the use of medication for diabetes mellitus. ResultsA total of 170 coronary heart disease including 113 myocardial infarctions occurred in non-fasting participants within the median 22-year follow-up period. Multivariable hazard ratios (HRs) of incident coronary heart disease for the participants with diabetic type compared with the normal type were 1.98 (0.84–4.68) for men, 3.39 (1.47–7.81) for women, and 2.47 (1.37–4.46) for total subjects. Corresponding HRs for myocardial infarction were 2.14 (0.83–5.55), 5.70 (2.21–14.67) and 3.17 (1.65–6.10), respectively. Multivariable HRs of incident coronary heart disease per one standard deviation of serum glucose levels were 1.17 (1.02–1.36), 1.19 (1.03–1.38), and 1.19 (1.08–1.32), respectively. The corresponding HRs for myocardial infarction were 1.18 (1.00–1.38), 1.27 (1.07–1.49) and 1.23 (1.10–1.37). ConclusionNon-fasting glucose concentration, either as diagnosis of diabetic type or as continuous variable, proved to be an independent predictor for incident coronary heart disease in middle-aged general population.

Treatment with the α-glucosidase inhibitor miglitol from the preonset stage in Otsuka Long-Evans Tokushima Fatty rats improves glycemic control and reduces the expression of inflammatory cytokine genes in peripheral leukocytes

Otsuka Long-Evans Tokushima Fatty (OLETF) rats, an animal model of type 2 diabetes mellitus, exhibit chronic and slowly progressive hyperglycemia with obesity. In this study, we examined whether dietary supplementation with the α-glucosidase inhibitor miglitol from the preonset stage improves glycemic control and reduces the gene expression of inflammatory cytokines in peripheral leukocytes. The OLETF rats were fed a control diet or a diet containing 800 ppm miglitol (miglitol diet) for 40 weeks from 5 weeks of age (preonset stage). We determined nonfasting blood glucose, blood 1,5-anhydroglucitol, and messenger RNA levels of inflammatory cytokines in peripheral leukocytes in these rats. Nonfasting blood glucose concentrations gradually increased in OLETF rats fed the control diet, with significant increases at weeks 28 and 40 compared with week 0. In contrast, nonfasting blood glucose levels did not increase in miglitol-treated rats during the experimental period. Miglitol-treated rats had lower nonfasting blood glucose levels and higher 1,5-anhydroglucitol levels, a marker for glucose fluctuations, at week 40 than control rats. The gene expression of inflammatory cytokines including interleukin-6, tumor necrosis factor-α, and interferon-γ in peripheral leukocytes gradually increased during the development of diabetes in control rats, but not in miglitol-treated rats. Our results suggest that dietary supplementation with miglitol from the preonset stage in OLETF rats improves glycemic control and reduces gene expression of cytokines related to inflammation in peripheral leukocytes.

Sex Differences in the Development of Diabetes in Mice with Deleted Wolframin (Wfs1) Gene

Wolfram syndrome, caused by mutations in the wolframin (Wfs1) gene, is characterised by juvenile-onset diabetes mellitus, progressive optic atrophy, diabetes insipidus and deafness. Diabetes tend to start earlier in boys. This study investigated sex differences in longitudinal changes in blood glucose concentration (BGC) in wolframin-deficient mice (Wfs1KO) and compared their plasma proinsulin and insulin levels with those of wild-type (wt) mice. Non-fasting BGC was measured weekly in 42 (21 males) mice from both groups at nine weeks of age. An intraperitoneal glucose tolerance test (IPGTT) was conducted at the 30 (th) week and plasma insulin, c-peptide and proinsulin levels were measured at the 32 (nd) week. At the 32 (nd) week, Wfs1KO males had increased BGC compared to wt males (9.40±0.60 mmol/l vs. 7.91±0.20 mmol/l; p<0.05). The opposite tendency was seen in females. Both male and female Wfs1KO mice had impaired glucose tolerance on IPGTT. Wfs1KO males had significantly lower mean plasma insulin levels than wt males (57.78±1.80 ng/ml vs. 69.42±3.06 ng/ml; p<0.01) and Wfs1KO females (70.30±4.42 ng/ml; p<0.05). Wfs1KO males had a higher proinsulin/insulin ratio than wt males (0.09±0.02 vs. 0.05±0.01; p=0.05) and Wfs1KO females (0.04±0.01; p<0.05). Plasma c-peptide levels in males were lower in Wfs1KO males (mean 55.3±14.0 pg/ml vs. 112.7±21.9 pg/ml; p<0.05). Male Wfs1KO mice had a greater risk of developing diabetes than female Wfs1KO mice. Low plasma insulin concentration with an increased proinsulin/insulin ratio in Wfs1KO males indicates possible disturbances in converting proinsulin to insulin which in long-term may lead to insulin deficiency. Further investigation is needed to clarify the mechanism for the sex differences in the development of diabetes in Wolfram syndrome.

The α-glucosidase inhibitor miglitol delays the development of diabetes and dysfunctional insulin secretion in pancreatic β-cells in OLETF rats

The Otsuka Long–Evans Tokushima Fatty (OLETF) rat, an animal model of type 2 diabetes, exhibits obesity, hyperglycemia and hyperlipidemia, with late onset of chronic and slowly progressive hyperinsulinemia. In this study, we examined effects of long-term dietary supplementation with the α-glucosidase inhibitor miglitol on the development of diabetes and the reduction of β-cells in the pancreas of OLETF rats. The OLETF rats were fed a control diet or a diet containing 800 ppm miglitol (miglitol diet) for 65 weeks from pre-onset stage (5 weeks old). The non-fasting blood glucose concentrations gradually increased in OLETF rats fed the control diet and, at week 64, were significantly higher than those in OLETF rats fed the miglitol diet and age-matched Long–Evans Tokushima Otsuka (LETO) rats, which are control, non-diabetic, non-obese rats of the same strain. Oral glucose tolerance tests revealed that OLETF rats fed the control diet showed pronounced impaired glucose tolerance, but those fed the miglitol diet did not. Furthermore, insulin concentrations after glucose-loading were significantly lower in OLETF rats fed the control diet than in those fed the miglitol diet. The islets of 65-week-old OLETF rats fed the control diet showed significant fibrosis and loss of β-cells, while those of age-matched control LETO rats had a normal appearance. Feeding OLETF rats a miglitol diet reduced fibrosis and the loss of β-cells. Our results suggest that dietary supplementation with miglitol from pre-onset stage in OLETF rats delays the onset and development of diabetes and preserves the insulin secretory function of pancreatic islets.

Pharmacokinetics and Efficacy of a Biweekly Dosage Formulation of Exenatide in Zucker Diabetic Fatty (ZDF) Rats

To develop an improved sustained-release (SR) formulation of exenatide (a therapy for patients with type 2 diabetes mellitus) in a biweekly dosage form with therapeutic efficacy comparable to that achieved with twice-daily injections of the drug. A SR formulation of exenatide, DA-3091, was prepared by single-emulsion solvent evaporation using poly(D,L-lactide-co-glycolide). Plasma exenatide, as well as plasma insulin, non-fasting blood glucose and HbA1c concentrations, and changes in food intake and body weight were evaluated in both Zucker diabetic fatty (ZDF) and ZDF lean control rats. After a single SC administration of DA-3091 (i.e., 2 mg/kg of exenatide), the plasma exenatide concentration increased and remained elevated in both groups. The concentrations of non-fasting blood glucose and HbA1c decreased significantly following a single SC injection of DA-3091 only in ZDF rats, indicating that the effects of exenatide are dependent on blood glucose concentration. On the other hand, both food intake and body weight gain were reduced in ZDF and ZDF lean control rats. A single injection of DA-3091 (i.e., 2 mg/kg of exenatide) lowered non-fasting blood glucose and HbA1c concentrations more effectively than 14 days of twice-daily administration of exenatide (i.e., 1.96 mg/kg of exenatide). DA-3091 has the potential to be used safely and efficaciously in a biweekly dosing regimen.

Chitosan/Gelatin Hydrogel Prolonged the Function of Insulinoma/Agarose Microspheres In Vivo During Xenogenic Transplantation

Purpose A chitosan/gelatin solution with glycerol 2-phosphate disodium salt hydrate in liquid phase at room temperature becomes a hydrogel at 37°C. The material can be used as an injectable cell carrier into the human body for gelation in situ. We hoped that the chitosan/gelatin hydrogel provided extra protection for insulinoma/agarose microspheres during xenogenic transplantation. Materials and Methods Mouse insulinoma was microencapsulated in agarose as microspheres, which were macroencapsulated in chitosan/gelatin hydrogel. Insulin secreting profiles were first demonstrated in vitro. Diabetic rats were injected subcutaneously with insulinoma/agarose microspheres or insulinoma/agarose microspheres suspended in chitosan/gelatin solution. The nonfasting blood glucose concentrations (NFBG) of diabetic rats were measured perioperatively. Rats were humanely killed 1 month postoperatively and the hydrogel was retrieved for histological examination. Results The insulinoma/agarose microspheres continually secreted insulin for 1 month when macroencapsulated in chitosan/gelatin hydrogel in vitro. The NFBG of diabetic rats injected with insulinoma/agarose microspheres decreased to euglycemic status albeit hyperglycemia was restored within 10 days. The NFBG of diabetic rats injected with chitosan/gelatin hydrogel, which contained insulinoma/agarose microspheres, was maintained at less than 200 mg/dL for 25 days. The histological section revealed immune cell infiltration and accumulation within the hydrogel and around the iusulinoma/agarose microspheres that may have contributed to the slowly increasing NFBG after day 25. Conclusion This study showed that chitosan/gelatin hydrogel can be used as a cell carrier for an injectable bioartificial pancreas; the hydrogel prolonged the function of cells encapsulated in agarose microspheres during xenogenic transplantation.

Chitosan/gelatin hydrogel as immunoisolative matrix for injectable bioartificial pancreas

The feasibility of using chitosan/gelatin hydrogel as immunoisolative matrix to provide an additional protection to the microencapsulated islet cells was demonstrated in this study. We hope that the use of hydrogel can extend the functional longevity of microencapsulated islet cells during xenotransplantation. Chitosan/gelatin solution with glycerol 2-phosphate disodium salt hydrate was prepared and utilized as a cell carrier. The biocompatibility of the chitosan/gelatin hydrogel was first established by using a mouse insulinoma cell line, NIT-1. Insulinoma cells were encapsulated in agarose as microspheres and then macroencapsulated in chitosan/gelatin hydrogel. In vitro cell activity, material-mediated cytotoxicity, cytokine-mediated cytotoxicity assay, and insulin secreting profiles of insulinoma/agarose microspheres macroencapsulated in chitosan/gelatin hydrogel were analyzed. For in vivo study, insulinoma/agarose microspheres with chitosan/gelatin solution was applied as an injectable bioartificial pancreas (BAPs). Insulinoma/agarose microspheres suspended in phosphate-buffered saline or in chitosan/gelatin solution was injected into the subcutaneous layer of diabetic rats. Non-fasting blood glucose (NFBG) concentration of rat was measured perioperatively. After pre-determined intervals, the chitosan/gelatin hydrogel containing insulinoma/agarose microspheres was retrieved for histologic examinations. Insulinoma/agarose microspheres macroencapsulated in hydrogel revealed functional activity and secreted insulin continually for 60 days in vitro. Chitosan/gelatin hydrogel was not cytotoxic to islet cells, and in contrast, the hydrogel showed cytoprotective effects against cytokine-mediated cytotoxicity. The NFBG of diabetic rats transplanted with free insulinoma/agarose microspheres was decreased to euglycemia but restored to hyperglycemia in 15 days. Contrarily, the NFBG of rats transplanted with insulinoma/agarose microspheres with hydrogel remained euglycemic for 42 days. Histologic sections revealed that the fibrous tissue envelopment and the infiltrated immune-related cells contributed to the dysfunction of BAPs. This study indicates that using chitosan/gelatin hydrogel as a cell carrier is feasible and can provide an additional protection for the microencapsulated islet cells during xenotransplantation.

Effects of chronic chromium picolinate treatment in uninephrectomized rat

Chromium picolinate [Cr(pic)3] is a nutritional supplement that is advocated as an adjuvant therapy for impaired glucose tolerance/type 2 diabetes because it improves glucose homeostasis. Because renal dysfunction is a major complication of type 2 diabetes, the potential impact of Cr(pic)3 on kidney function requires due consideration. This investigation takes added importance because the kidney is not only the principal route of elimination for chromium but also an organ that preferentially accumulates it. To avoid the confounding influence of chronic hyperglycemia, and its associated complications, we used the unilaterally nephrectomized (UNX) rat that shows impaired kidney function with age. We tested the hypothesis that chronic treatment of the UNX rat with Cr(pic)3 exacerbates the age-related decline in renal function. Accordingly, UNX rats were fed a diet lacking (eg, control; n = 5) or containing 5 mg/kg of Cr(pic)3 (n = 7) for 60 days. The treatment did not affect glucose tolerance as reflected by lack of any effect on changes in blood glucose concentration during glucose tolerance testing. Although nonfasting blood glucose concentrations were similar between the 2 groups, plasma insulin concentration was lower in the Cr(pic)3-treated group ( P < .05), suggesting improved insulin sensitivity. Body weight, blood pressure, heart rate, daily food and fluid consumption, daily urinary fluid and electrolyte excretions, urine osmolality, and daily protein excretion were similar between the 2 groups before and during Cr(pic)3 treatment. Although renal excretory responses to acute administration of a 5% isotonic saline volume load were similar between the 2 groups, the Cr(pic)3-treated group displayed a more robust ability to excrete a 10% isotonic saline volume load, an effect primarily related to reduced tubular reabsorption of the filtered fluid and sodium loads. In conclusion, chronic Cr(pic)3 did not adversely affect renal function. Rather, the treatment improved the ability of the animal to dispose of an acute isotonic saline volume load, suggesting preservation of renal function in the UNX rat.