miR-10b and miR-223-3p in serum microvesicles signal progression from prediabetes to type 2 diabetes.

PURPOSE: Type 2 diabetes frequently remains undiagnosed for years, whereas early detection of affected individuals would facilitate the implementation of timely and cost-effective therapies, hence decreasing morbidity. With the intention of identifying novel diagnostic biomarkers, we characterized the miRNA profile of microvesicles isolated from retroactive serum samples of normoglycemic individuals and two groups of subjects with prediabetes that in the following 4 years either progressed to overt diabetes or remained stable. METHODS: We profiled miRNAs in serum microvesicles of a selected group of control and prediabetic individuals participating in the PREDAPS cohort study. Half of the subjects with prediabetes were diagnosed with diabetes during the 4 years of follow-up, while the glycemic status of the other half remained unchanged. RESULTS: We identified two miRNAs, miR-10b and miR-223-3p, which target components of the insulin signaling pathway and whose ratio discriminates between these two subgroups of prediabetic individuals at a stage at which other features, including glycemia, are less proficient at separating them. In global, the profile of miRNAs in microvesicles of prediabetic subjects primed to progress to overt diabetes was more similar to that of diabetic patients than the profile of prediabetic subjects who did not progress. CONCLUSION: We have identified a miRNA signature in serum microvesicles that can be used as a new screening biomarker to identify subjects with prediabetes at high risk of developing diabetes, hence allowing the implementation of earlier, and probably more effective, therapeutic interventions.

Pancreatic polypeptide regulates glucagon release through PPYR1 receptors expressed in mouse and human alpha-cells.

BACKGROUND: Plasma levels of pancreatic polypeptide (PP) rise upon food intake. Although other pancreatic islet hormones, such as insulin and glucagon, have been extensively investigated, PP secretion and actions are still poorly understood. METHODS: The release of PP upon glucose stimulation and the effects of PP on glucagon and insulin secretion were analyzed in isolated pancreatic islets. Expression of PP receptor (PPYR1) was investigated by immunoblotting, quantitative RT-PCR on sorted pancreatic islet cells, and immunohistochemistry. RESULTS: In isolated mouse pancreatic islets, glucose stimulation increased PP release, while insulin secretion was up and glucagon release was down. Direct exposure of islets to PP inhibited glucagon release. In mouse islets, PPYR1 protein was observed by immunoblotting and quantitative RT-PCR revealed PPYR1 expression in the FACS-enriched glucagon alpha-cell fraction. Immunohistochemistry on pancreatic sections showed the presence of PPYR1 in alpha-cells of both mouse and human islets, while the receptor was absent in other islet cell types and exocrine pancreas. CONCLUSIONS: Glucose stimulates PP secretion and PP inhibits glucagon release in mouse pancreatic islets. PP receptors are present in alpha-cells of mouse and human pancreatic islets. GENERAL SIGNIFICANCE: These data demonstrate glucose-regulated secretion of PP and its effects on glucagon release through PPYR1 receptors expressed by alpha-cells.

Carbohydrate Management in Athletes with Type 1 Diabetes in a 10 km Run Competition.

The aim of this study was to identify the real consumption of CHO during a 10 km competitive run, to compare data with the recommended quantities according to current guidelines, and to analyse the clinical events associated with these different amounts. Protocol 1: observational study including 31 athletes with T1D and 127 athletes without diabetes, comparing data taken from dietary records of CHO intake on the competition day. Protocol 2: single-blind randomized trial in 18 athletes with T1D, testing a pre-exercise CHO supplement of 0.7 g CHO·kg(- 1) (n=10) or 0.35 g CHO·kg(- 1) (n=8). The results showed that T1D athletes consumed a lower quantity of CHO than athletes without diabetes at their usual breakfast and during the meal taken<1 h after the competition, but no differences were found in the supplement taken before the competition. In the randomized study, athletes consuming the higher dose of CHO (0.7 g CHO·kg(- 1)) showed increased glycemic levels, comparing with the lower dose (0.35 g CHO·kg(- 1)). In conclusion, athletes with T1D seem to increase CHO intake prior to the competition consuming similar amounts to those athletes without diabetes, but consuming smaller quantities of CHO than the recommended amounts. This appears to induce a more stable glycemic response, in comparison with supplements with high-CHO content.

Hyperglycemia following recovery from hypoglycemia worsens endothelial damage and thrombosis activation in type 1 diabetes and in healthy controls.

BACKGROUND AND AIMS: Hypoglycemia produces thrombosis activation, but little attention has been paid to the effects of hyperglycemia following recovery from hypoglycemia on thrombosis activation. METHODS AND RESULTS: In both twenty-two healthy subjects and twenty-one matched persons with type 1 diabetes, recovery from a 2-h induced hypoglycemia was obtained by reaching normo-glycemia or hyperglycemia for another 2 h. After this, normal glycemia was maintained for the following 6 h. Hyperglycemia after hypoglycemia was also repeated with the concomitant infusion of vitamin C. In both controls and people with diabetes, the recovery with normo-glycemia was accompanied by a significant improvement of Von Willebrand factor (vWF), prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III-complexes (TAT), P-selectin, plasminogen activator inhibitor-1 (PAI-1), nitrotyrosine and 8-iso-prostaglandin F2α (8-iso-PGF2α) (p < 0.01 vs hypoglycemia for all the parameters), all directly affected by hypoglycemia itself (p < 0.01 vs baseline for all the parameters). On the contrary, the recovery with hyperglycemia after hypoglycemia worsens all these parameters (p < 0.01 vs normoglycemia for all the parameters), an effect persisting even after the additional 6 h of normo-glycemia. The effect of hyperglycemia following hypoglycemia was partially counterbalanced when vitamin C was infused (p < 0.01 vs hyperglycemia alone for all the parameters), suggesting that hyperglycemia following hypoglycemia may activate thrombosis through the oxidative stress production. CONCLUSION: This study shows that, in type 1 diabetes as well as in controls, the way in which recovery from hypoglycemia takes place could play an important role in favoring the activation of thrombosis and oxidative stress, widely recognized cardiovascular risk factors.

Glucose regulation of a cell cycle gene module is selectively lost in mouse pancreatic islets during ageing.

AIMS/HYPOTHESIS: Transcriptional networks in beta cells are modulated by extracellular signals such as glucose, thereby ensuring beta cell adaptation to systemic insulin demands. Ageing is a main risk factor for type 2 diabetes and has been associated with perturbed expression of genes essential for beta cell function. We aimed to uncover glucose-dependent gene modules in mouse pancreatic islets and investigate how this regulation is affected by ageing. METHODS: Global gene expression was assessed in pancreatic islets from young and aged wild-type and Cdkn2a (Ink4a/Arf)-deficient mice exposed to different glucose concentrations. Gene modules were identified by gene ontology and gene set enrichment analysis. RESULTS: Gene expression profiling revealed that variations in glucose levels have a widespread and highly dynamic impact on the islet transcriptome. Stimulatory glucose levels induced the expression of highly beta cell-selective genes and repressed the expression of ubiquitous genes involved in stress and antiproliferative responses, and in organelle biogenesis. Interestingly, a module comprising cell cycle genes was significantly induced between non-stimulatory and stimulatory glucose concentrations. Unexpectedly, glucose regulation of gene expression was broadly maintained in islets from old mice. However, glucose induction of mitotic genes was selectively lost in aged islets and was not even restored in the absence of the cell cycle inhibitors p16(INK4a) and p19(ARF), which have been implicated in the restricted proliferative capacity of beta cells with advanced age. CONCLUSIONS/INTERPRETATION: Glucose-dependent transcriptional networks in islets are globally conserved during ageing, with the exception of the ability of stimulatory glucose levels to induce a cell cycle gene module.

Physical activity patterns in type 1 diabetes in Spain: The SED1 study.

AIMS: To describe the physical activity (PA) frequency and intensity in the Spanish type 1 diabetes mellitus (T1D) population and its association with their glycemic control. METHODS: A cross-sectional observational study was carried out in 75 Spanish public hospitals (the SED1 study). T1D patients over 14years of age self-completed the International Physical Activity Questionnaire (IPAQ) to determine their level of exercise. The relationship between PA frequency and intensity in T1D patients and glycemic control and the diabetes therapeutic education received were analyzed. RESULTS: A total of 592 patients were evaluable. A 6.8% of the sample performed light PA, 20.9% moderate and 72.3% vigorous. Estimated PA presented a high inter-individual variability. Men consumed more energy (METS) than women, these differences being more noticeable in vigorous METS (2865.80 in men vs 1352.12 in women). Women invested more min/week in the domestic and garden area (639.03 vs 344.39, p = 0,022). A correlation between glycemic control and the METs was not observed. CONCLUSIONS: The Spanish T1D population performed PA in a higher frequency and intensity than the general population. A relationship between PA and glycemic control couldn´t be shown. However, limitations of the study should be kept in mind to discard a long-term positive influence.

One year follow-up in a group of half-marathon runners with type-1 diabetes treated with insulin analogues.

AIM: The objective was to describe the strategies that type-1 diabetic runners treated with insulin analogues apply in a half-marathon race and the changes after a year of experience participating in long-distance athletic competitions. METHODS: Fourteen male amateur athletes with type-1 diabetes treated with insulin analogues, participating in two consecutive editions of the same half-marathon were assessed. Data about insulin dosage and carbohydrate intake from their regular daily training and from the two half-marathons were compared. Capillary glycemic values from throughout the competition and in the following 24 h period were monitored and the frequency of hypoglycemia and glucose fluctuations was compared, using MAGE method. RESULTS: During the half-marathon day, athletes reduced total insulin doses a 18.3% in 2006 and 14.2% in 2007, with a reduction of basal insulin (23.3% in 2006 vs 20.4% in 2007, P<0.05) and of short-insulin at breakfast prior to the competition (31.7% in 2006 vs 15.3% in 2007, P<0.001). Carbohydrate consumption during competition was higher in second edition (49.0±16.4 g vs 59.1±11.2 g, P<0.05). Glycaemic excursions, assessed by MAGE, were higher in the first edition (108.1±47.3 mg/dL vs 62.2±45.6 mg/dL, P<0.05). CONCLUSION: Type-1 diabetes athletes, treated with insulin analogues, participating in half-marathon competitions exhibited less insulin reduction in comparison with traditional guidelines and they needed to take an important quantity of carbohydrate supplements to avoid hypoglycemia during and after the competition. We suggest reconsidering traditional recommendations of insulin therapy and carbohydrate supplementation (amount and timing) to athletes treated with current insulin analogues participating in long-distance competitions.

Role of iduronate-2-sulfatase in glucose-stimulated insulin secretion by activation of exocytosis.

Iduronate-2-sulfatase (IDS) is a lysosomal enzyme expressed in pancreatic islets responsible for the degradation of proteoglycans such as perlecan and dermatan sulfate. Previous findings of our group demonstrated the involvement of IDS in the normal pathway of lysosomal degradation of secretory peptides, suggesting a role of this enzyme in beta-cell secretory functionality. The present study was undertaken to characterize the effect of IDS overexpression on insulin release. INS1E cells were transiently transfected with a construct encoding human IDS (hIDS). hIDS overexpression was associated with a gain of function detected by a reduction in heparan sulfate content. hIDS potentiated the glucose-stimulated insulin secretory response compared with controls (61%) with no changes in insulin mRNA levels or insulin peptide content. Results on quantification of the exocytotic process showed a significant increase in hIDS-transfected cells compared with controls. Furthermore, ultramorphological analysis demonstrated an increase in the number of granules in the immediate vicinity of the plasma membrane in hIDS-transfected cells and a decrease in total vesicles per square micrometer. hIDS overexpression induced phosphorylation of protein kinase C (PKC) alpha and its newly myristoylated alanine-rich C kinase substrate, MARCKS. We conclude that IDS has a role in glucose-stimulated insulin secretion via a mechanism that involves the activation of exocytosis through phosphorylation of PKCalpha and MARCKS.

Calcium elevation in mouse pancreatic beta cells evoked by extracellular human islet amyloid polypeptide involves activation of the mechanosensitive ion channel TRPV4.

AIMS/HYPOTHESIS: To investigate the mechanism by which human islet amyloid polypeptide (hIAPP) fibril formation results in calcium influx across the plasma membrane of pancreatic beta cells, and its association with apoptosis. METHODS: Cytoplasmic intracellular calcium concentrations ([Ca(2+)](i)) were monitored for 2 h as the 340/380 nm fluorescence ratio in fura-2 loaded cells of the MIN6 mouse pancreatic beta cell line. Cell morphology was evaluated by transmission electron microscopy, and viability by FACS. RESULTS: hIAPP (10 micromol/l) increased [Ca(2+)](i) in 21% of MIN6 cells in standard buffer, and in 8% of cells in Na(+)-free buffer. Transient receptor potential (TRP) channel inhibitors (gadolinium and ruthenium red) prevented the [Ca(2+)](i) rise under both conditions, whilst nifedipine was only effective in the presence of Na(+). hIAPP increased apoptosis in both insulinoma cells and islets in primary culture, and cell viability was partially rescued by ruthenium red (p < 0.001). By RT-PCR, we detected expression of the mechanosensitive TRP cation channel subfamily V member 4 (Trpv4) in MIN6 cells and mouse pancreas. Small interference RNA against Trpv4 prevented hIAPP-induced [Ca(2+)](i) rises, decreased hIAPP-triggered expression of the endoplasmic reticulum (ER) stress response, and reduced hIAPP-triggered cell death by 50% (p < 0.05). CONCLUSIONS/INTERPRETATION: Alterations in [Ca(2+)](i) play a key role in hIAPP-induced beta cell cytotoxicity. By electron microscopy, we detected extracellular hIAPP aggregates adjacent to irregular invaginated regions of the plasma membrane. We propose that TRPV4 channels may sense physical changes in the plasma membrane induced by hIAPP aggregation, enabling Ca(2+) entry, membrane depolarisation and activation of L-type Ca(2+) channels. Decreasing the activity of TRPV4 prevented hIAPP-induced [Ca(2+)](i) changes, reduced hIAPP-triggered ER stress and improved cell viability.

Regulation of islet amyloid polypeptide in human pancreatic islets.

This study investigated the effect of glucose on islet amyloid polypeptide secretion, content, and mRNA synthesis of human pancreatic islets. The release of islet amyloid polypeptide from fresh isolated islets in response to glucose was parallel to that of insulin. The islet amyloid polypeptide-to-insulin molar ratios in response to 5.5 and 16.7 mM glucose were 1:16 and 1:15 respectively. Islets were cultured for 1 and 7 days at two different glucose concentrations (5.5 and 16.7 mM). The islet amyloid polypeptide response to the 1-day culture was similar to that of the fresh islets; however, after the 7-day culture the islet amyloid polypeptide and insulin secretory responses to glucose were dissociated. The insulin response of islets to a high-glucose stimulus was significantly (P < 0.001) increased, whereas the islet amyloid polypeptide response of islets to the same stimulus was blunted. The IAPP content was greater than insulin content in a molar ratio (1:50 to 1:30) after long exposure of islets to concentrations of high glucose even though the increase was significant for both peptides (P < 0.005). Northern blot analysis of each cultured condition showed an increase of both mRNA IAPP and insulin signals after exposure of islets at 16.7 mM glucose, the maximum mRNA expression being after long exposure to high-glucose concentrations. Quantification of both signals by densitometry showed a greater increase for islet amyloid polypeptide than for insulin. These findings suggest that IAPP can be accumulated in beta-cells after long exposure of human islets to high-glucose concentrations, because glucose increases IAPP synthesis but not secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of isradipine and nifedipine retard in hypertensive patients with type II diabetes mellitus.

Twenty patients were randomized to receive either 2.5 mg isradipine twice daily or 20 mg nifedipine retard once daily for 6 months. After 2 weeks of placebo wash-out, evaluations were carried out every 4 weeks. These evaluations included assessment of blood pressure, lipid profile, hemoglobin A1 sigma glucagon, C peptide, and insulin requirements. Both isradipine and nifedipine retard lowered systolic and diastolic blood pressures to normal values (P < .001). However, isradipine was accompanied by a decrease in heart rate (P < .005). Neither drug modified hemoglobin A1c or the glycemic profile. The endogenous insulin-secretion response decreased in both treatment groups (P < .05). In conclusion, isradipine and nifedipine retard are efficacious in the treatment of hypertension in patients with type II diabetes mellitus, and neither treatment produces modification of metabolic control.

Signals related to glucose metabolism regulate islet amyloid polypeptide (IAPP) gene expression in human pancreatic islets.

Intracellular pathways involved in glucose stimulation of IAPP gene expression were studied in human pancreatic islets. Glucose (16.7 mM), but not mannose, caused a 2.3-fold increase in IAPP mRNA levels; this effect was inhibited by actinomycin D. In the presence of the non-metabolizable 6-deoxyglucose (16.7 mM) IAPP mRNA levels were markedly depleted. Both mannoheptulose and verapamil blocked glucose-induced stimulation of the IAPP gene. The magnitude of the insulin gene response to glucose was smaller (1.3-fold); none of the above-mentioned agents had significant effects on insulin mRNA content. Tunicamycin elicited a 2.4- and 2.7-fold increase in IAPP mRNA levels in the low and high glucose media, respectively; however, it did not change insulin mRNA. It had no effect on rat IAPP or insulin mRNAs, either. We conclude that IAPP gene expression is regulated by signals derived from glucose metabolism and that intracellular calcium may be involved in this response. IAPP and insulin genes are not co-regulated in cultured human pancreatic islets.

High glucose concentration favors the selective secretion of islet amyloid polypeptide through a constitutive secretory pathway in human pancreatic islets.

We studied the contribution of the constitutive and the regulated pathways to the total secretion of islet amyloid polypeptide (IAPP) in human pancreatic islets after prolonged culture at either 5.5 or 24.4 mM glucose. In islets cultured in low concentrations of glucose, the secretion of IAPP in response to glucose was unaffected by brefeldin A (BFA) and completely blocked by ethyleneglycoltetraacetic acid. In islets cultured in high glucose concentrations, it was strongly inhibited by both agents. BFA had no effect on the glucose-induced insulin secretion. The determination of the islet peptide contents and the mRNA levels revealed a several-fold increase in the IAPP/insulin molar ratio of islets cultured in high glucose concentrations. Thus, prolonged exposure of human islets to high concentrations of glucose results in an increase in the synthesis of IAPP with respect to insulin. As a result, the release of IAPP through a mechanism sensitive to BFA is favored. These data support the hypothesis that IAPP and insulin are regulated in a noncoordinated way in human pancreatic islets.

Reduction of islet amylin expression and basal secretion by adenovirus-mediated delivery of amylin antisense cDNA.

Reduction of amylin content and secretion in rat islets was attempted by transduction with an adenovirus bearing a 0.2-kb fragment of rat amylin cDNA inserted in the antisense orientation (AdCMV-alpha amylin). Exposure of islets to AdCMV-alpha amylin at a multiplicity of infection (moi) of 200 (1.2 x 10(7) pfu/ml) reduced amylin mRNA levels by 37 +/- 5% (p < 0.005), whereas infection with an adenovirus expressing the reporter gene of beta-galactosidase (AdCMV-lacz) did not modify amylin expression. Transduction with the antisense construct was specifically associated with the decrease (30 +/- 6%; p < 0.001) in the amylin content. Insulin content was unaltered in AdCMV-alpha amylin islets compared to AdCMV-lacz-transduced or untransduced cells. Basal amylin secretion (2.8 mM glucose) was 36 +/- 3% (p < 0.005) lower in AdCMV-alpha amylin islets than in untransduced or AdCMV-lacz-transduced islets. In contrast, no difference in amylin secretion in response to high glucose concentrations (16.7 mM) was detected in AdCMV-alpha amylin-transduced islets. Thus, a reduction of amylin content and basal secretion in islet cells can be achieved by the adenovirus-mediated expression of antisense RNA.

Beta-cell function abnormalities in islets from an adult subject with nesidioblastosis and autoantibodies against the islet cells.

Human islets from an adult subject with nesidioblastosis were isolated and used to perform in vitro studies. Isolated nesidioblastotic islets showed an increased basal rate of insulin secretion (nesidioblastotic islets, 81.3 +/- 6.4 vs. control islets, from cadaveric organ normal donors, 10.2 +/- 0.9 microU/islet/90 min) without any further release with increasing glucose concentration. In addition, islets isolated from the pancreas with nesidioblastosis contained more insulin than control islets, 1,547.0 +/- 128.7 vs. 935.0 +/- 51.7 microU/islet, and the levels of insulin mRNA were also higher than those measured in controls. Interestingly, the serum of the subject with nesidioblastosis contained autoantibodies that stained brightly and selectively a population of islet cells whose distribution coincided with that expected of alpha cells. In summary, pancreatic islets in nesidioblastosis display beta-cell functional abnormalities. Moreover, the finding of antibodies against islet cells is a common feature in the serum of nesidioblastotic subjects; nevertheless, their pathological significance warrants further investigation.

Autoantibodies against mitochondrial glycerophosphate dehydrogenase in patients with IDDM.

The mitochondrial enzyme FAD-linked glycerophosphate dehydrogenase (mGDH) plays a key role in the recognition of D-glucose as a stimulus for insulin release from the pancreatic islet B-cell. This study reveals that autoantibodies against this enzyme are not uncommonly found in patients with insulin-dependent diabetes mellitus (IDDM) examined at the onset of the disease. Antibodies reacting with a recombinant mGDH fragment product were observed in the serum of four out of 15 type-1 diabetics, but in none of 15 control subjects. The serum of patients positive for the recombinant mGDH fragment also recognized native mGDH in a rat testis extract, provided that the enzymatic protein was first exposed to an anti-mGDH rabbit serum. Antibodies against mGDH were also found in four out 12 patients with autoimmune thyroiditis. These findings reveal that a mitochondrial enzyme, that represents an essential component of the islet B-cell glucose-sensing device, may act as an antigenic determinant in patients with IDDM or other autoimmune diseases.

Suppression by insulin treatment of glucose-induced inhibition of insulin release in non-insulin-dependent diabetics.

Although restoration of normoglycemia in non-insulin-dependent diabetic subjects improves insulin release evoked by several secretagogues, conflicting data were reported concerning the effect of intensive insulin therapy on the first-phase response of the B-cell to an intravenous glucose challenge. In the present study, 14 non-insulin-dependent diabetics underwent an intravenous glucose test performed before and after 20 h of glycemic normalization. Before insulin treatment, glucose failed, as a rule, to provoke an early positive secretory response. On the contrary, a paradoxical inhibition of insulin release was observed in most patients. This phenomenon was reproducible when a second test was performed 120 min after the first one. The paradoxical inhibition was not observed any more after glycemic normalization. As judged from the paired difference (delta) between the early increment in insulin release before and after insulin treatment, normoglycemia resulted in an improved secretory response (delta greater than 5.0 microU/ml) in seven patients, whilst the first-phase response remained little affected (delta less than 3.0 microU/ml) in the other seven subjects. These findings suggest that an impaired first-phase response to glucose does not always represent an irreversible primary defect of the pancreatic B-cell in diabetic subjects.

[Pseudomononucleosis induced by diphenylhydantoin (author's transl)]. / Pseudomononucleosis inducida por defenilhidantoína.

The authors report a patient who developed a mononucleotic syndrome after 2 months treatment with diphenylhydantoin. The clinical and biological criteria needed to establish the diagnosis of pseudomononucleosis are listed, while other possible causes described in the literature have been excluded. Complications which may occur during anti-convulsant therapy with diphenylhydantoin are reviewed and the few cases of pseudomononucleosis in the literature noted. Diagnosis was established through eliminating other possible causes, as the only definite test-drug induced reaction-is hazardous to the patient.

Amylin exerts osteogenic actions with different efficacy depending on the diabetic status.

Amylin displays osteogenic features, but its role in diabetic osteopenia is unclear. We examined the possible osteogenic action of amylin infusion for 3days into fructose-induced insulin-resistant (IR) and streptozotocin-induced type 2 diabetic (T2D) and normal (N) rats. Amylin failed to affect glycaemia or parathyroid hormone levels in any group, but reduced hyperinsulinemia in IR rats. In N rats, amylin increased bone formation rate and reduced osteoclast surface and erosive surface in the femoral metaphysis, and increased osteoprotegerin (OPG)/receptor activator of NFκB ligand (RANKL) mRNA ratio in the tibia. In T2D rats, amylin normalized trabecular structure parameters and increased osteoblast number and osteocalcin (OC) expression in long bones. In contrast, in IR rats, no apparent osteogenic effect of amylin in the femur was observed, although both OC and OPG/RANKL ratio were increased in the tibia. Our findings demonstrate a different osteogenic efficacy of amylin in two diabetic settings.

Amylin effect in extrapancreatic tissues participating in glucose homeostasis, in normal, insulin-resistant and type 2 diabetic state.

Amylin is co-secreted with insulin, responds to the same stimuli, is anorectic, lowers body weight by reducing fat mass, and is proposed for diabetes treatment. We examined the effect of a 3-day constant infusion of close to physiological doses of amylin in Wistar rats, on glucotransporter expression, glycogen content (G), glycogen synthase a activity (GSa) and glucose transport (GT), in liver, muscle and fat from insulin resistant (IR) and type 2 diabetic (T2D) models, compared to normal (N) animals; plasma glucose and insulin were measured. Plasma insulin in IR was higher than in N or T2D, and amylin normalized the value. In both, IR and T2D, liver G was lower than normal, accompanied by GLUT-2, mRNA and protein, higher and lower, respectively, than in N; amylin normalized G in both groups, without changes in GLUT-2, except for an mRNA increase in T2D. In IR and T2D, muscle GSa was reduced, together with respective over- and under-GLUT-4 expression; amylin induced only a trend toward GSa normalization in both groups. In isolated adipocytes, GT and GLUT-4 in IR and T2D were lower and higher, respectively, than in N; after amylin, not only GT was normalized in both groups but also the response to insulin was much more pronounced, including that in N, without major changes in GLUT-4. This suggests that the beneficial effect of amylin in states running with altered glucose homeostasis could occur by partially acting on the hexose metabolism of the liver and mainly on that of the adipose tissue.