Insulin-dependent Diabetes Mellitus Type Research Articles

Ingested (Oral) SIRS Peptide 1-21 Suppresses Type 1 Diabetes in NOD Mice

Type 1 diabetes (T1D) is a chronic disorder that results from autoimmune destruction of the insulin-producing pancreatic beta cell. The nonobese diabetic (NOD) mouse is a model of the human autoimmune disease T1D. Soluble immune response suppressor (SIRS) is a nonspecific protein suppressor of immune response produced by immunomodulatory T cells stimulated by type I interferon (IFN). SIRS inhibits antibody responses in vivo, lipopolysaccharide (LPS)-induced fever, and delayed-type hypersensitivity (DTH) responses. Previous investigators have isolated the N-terminal sequence of SIRS protein consisting of 21 amino acids. Mice ingesting 1 microg SIRS peptide 1-21 showed significant delayed onset of T1D and a decreased frequency of T1D compared with mock-fed and 10-microg-fed mice and a significant decrease in islet inflammation. There were significant decreases in islet lymphocyte chemokine production of granulocyte-macrophage colony-stimulating factor (GM-CSF), macrophage inflammatory protein-1 gamma (MIP-1 gamma), regulated upon activation, normal T cell-expressed, and presumably secreted (RANTES), and stromal cell-derived factor-1 (SDF-1) in the SIRS-fed mice, factors important in migration of inflammatory cell into the islets. Ingested (oral) SIRS peptide inhibits clinical T1D by decreasing target organ cellular migration of islet destructive populations by suppression of islet lymphocyte chemokine secretion.

Unexpected functional consequences of xenogeneic transgene expression in β‐cells of NOD mice

We describe unexpected alterations in the non-obese diabetic (NOD/Lt) mouse model of type 1 diabetes (T1D) following forced beta-cell expression of non-mammalian genes ligated to an insulin promoter sequence. These include the jellyfish green fluorescent protein (GFP), useful for beta-cell identification, and the bacteriophage P1 Cre recombinase, necessary for beta cell-specific ablation of a gene using a Cre-loxP system. Homozygous expression of GFP, driven by the mouse insulin 1 gene promoter (MIP-GFP) in a single transgenic line of NOD mice, produced T1D in postnatal mice that was not associated with insulitis, but rather beta cell-depleted islets. Hemizygous transgene expression suppressed spontaneous autoimmune T1D in females, and produced a male glucose intolerance syndrome associated with age-dependent declines in plasma insulin content. Among lines of transgenic NOD/Lt mice expressing Cre recombinase driven by the rat insulin 2 promoter (RIP-Cre), high, non-mosaic expression correlated with suppressed T1D development. These findings emphasize the need for careful characterization of genetically manipulated NOD mouse stocks to insure that model characteristics have not been compromised.

Decreased blood dendritic cell counts in type 1 diabetic children

In this study DC numbers, phenotype and DC responses to the Toll-like receptor (TLR)-3 ligand, poly I:C, were examined in new-onset Type 1 diabetes (T1D) patients (ND) and in established T1D patients (ED). Absolute blood myeloid DC (MDC) and plasmacytoid DC (PDC) numbers were decreased in ND and ED patients compared to age-matched controls. The decrease in MDC and PDC counts was less evident in patients with a combination of T1D and coeliac disease (CD) or CD alone. The age-dependent decline in blood DC numbers, found in control children, was not evident in ND patients, such that 2–10 years old ND children had similar MDC and PDC numbers to 15–17 years old controls. In ED patients the t-score of MDC and PDC numbers related to the age of diagnosis but not to disease duration. Blood DC in T1D patients were not distinguished from those of controls by the levels of HLA-DR, CD40 and CD86 expression or the percentage of DC expressing cytokines, IL-12, IL-10, IL-6 and TNF-α, in responses to poly I:C. If low DC numbers are shown to contribute to the autoimmunity in T1D, interventions aimed to increase DC numbers may mitigate against β-cell loss.

A Work in Progress, but a Useful Construct

The metabolic syndrome is a construct that has come into common usage over the last few decades. In 1956, Jean Vague1 first demonstrated that upper-body obesity determined predisposition to diabetes mellitus, atherosclerosis, gout, and renal calculi; however, it was the presentation of this concept by Gerald Reaven in his Banting Lecture in 19882 that initiated the current focus on this entity as a clinical and pathological construct. Dr Reaven suggested that 3 major conditions—non–insulin-dependent diabetes mellitus (type 2 diabetes mellitus), hypertension, and coronary artery disease—had an causal commonality (resistance to insulin-stimulated glucose uptake and hyperinsulinemia) and referred to this constellation of abnormalities as “syndrome X.” He did not include abdominal obesity in the original description, nor did he comment significantly on a potential clinical role for his observations. In fact, his concluding sentences stated, “What remains to be seen is the magnitude of the role that resistance to insulin-stimulated glucose uptake plays in the etiology of human disease. I can only hope that this presentation has outlined the possibilities for future efforts to answer this question.” Response by Kahn p 1818 Since that time, this construct has evolved conceptually and functionally into an entity that many refer to as a “syndrome.” More recently, there have been many questions about the legitimacy of this designation, summarized by Kahn et al3 in a September 2005 position statement for the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD). Their comments called into question many of the assumptions that underlay the designation of “syndrome,” and they posed the following key questions: How clear is the existing definition of the metabolic syndrome for diagnostic purposes? How useful is the syndrome definition in predicting cardiovascular disease (CVD) risk? Do the individual components of the syndrome convey “risk” …

Association of the interleukin‐2 receptor alpha (IL‐2Rα)/CD25 gene region with Graves’ disease using a multilocus test and tag SNPs

A small number of immune response genes have been consistently associated with the common autoimmune conditions. Recently, a linkage disequilibrium (LD) mapping approach, using tag single nucleotide polymorphisms (SNPs), identified genetic association between type 1 diabetes (T1D) and the interleukin-2 receptor alpha (IL-2Ralpha)/CD25 gene region on chromosome 10p15. Because certain autoimmune diseases, such as autoimmune thyroid disease (AITD) and T1D cluster together in certain families, we sought to determine if the TID-associated CD25 region was also associated with Graves' disease (GD). We performed a case-control association study of 20 tag SNPs. 1896 GD patients were collected from seven major centres in the UK and 1822 geographically matched controls from the 1958 British Birth Cohort. The 20 tag SNPs were analysed using a multilocus test to identify an association between GD and the CD25 region. Odds ratios (ORs) were calculated for the tag SNPs, allowing a comparison with previous results for T1D. RESULTS The multilocus test provided statistical evidence of an association between GD and the CD25 region (P = 4.5 x 10(-4)), with the pattern of association of the 20 tag SNPs similar to that found in T1D. CONCLUSIONS Association with GD, as well as that previously reported with T1D, suggests that the CD25 region is acting as a general susceptibility locus for autoimmune disease, and is consistent with a major role for the IL-2-receptor pathway in the development and function of T cells in the control of autoimmunity.

No Evidence of Association of CTLA-4 -318 C/T, 159 C/T, 3′ STR and SUMO4 163 AG Polymorphism with Autoimmune Diabetes

Autoimmune diabetes is an organ specific and multifactorial disorder including insulin dependent diabetes mellitus (Type 1 Diabetes) and latent autoimmune diabetes in adults (LADA), which progresses to insulin dependency because of the beta cells destruction. Several polymorphisms in different genes have been associated with diabetes. The CTLA4 gene is considered a down regulator of T cell function, and the SUMO4 gene encodes a small ubiquitin-like modifier implicated in the intensity and duration of the immune response. We selected 62 LADA patients, 123 patients with Type 1 diabetes patients and 136 unrelated volunteers to study CTLA4 -318 C/T, 159 C/T, 3′ STR and SUMO4 163 A/G polymorphisms by PCR. There was a statistical difference significant in the frequency of the allele 209pb for the 3′STR between LADA and Type 1 diabetes patients but not with respect the normal group, the frequencies were found to be 6.9%, 1.0% and 1.9%, respectively. However, no association with either of the polymorphisms has been found in the studied population. The knowledge of the several susceptibility loci in autoimmune diabetes will enhanced the prediction of individuals at high risk of developing the disease in order to establish the best treatment and the prevention of autoimmune diabetes.

Perinatal Factors Associated With Cerebral Palsy in Children Born in Sweden

To identify perinatal factors associated with cerebral palsy (CP). This was a case-control study based on the Swedish Medical Birth Registry and the Swedish Hospital Discharge Registry, including 2,303 infants born in Sweden 1984-1998 with a diagnosis of CP and 1.6 million infants without this diagnosis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Infants born preterm had a highly increased risk for CP, and constituted 35% of all cases; OR 34 (95% CI 29-39) in weeks 23-27, OR 37 (95% CI 32-42) in weeks 28-29, OR 26 (95% CI 23-30) in weeks 30-31, and OR 3.9 (95% CI 3.4-4.4) in weeks 32-36. Boys had a higher risk (sex ratio 1.36:1), particularly before term (sex ratio 1.55:1). Other factors associated with CP were being small or large for gestational age at birth, abruptio placentae (OR 8.6, 95% CI 5.6-13.3), maternal insulin-dependent diabetes mellitus type 1 (OR 2.1, 95% CI 1.4-3.1), preeclampsia (OR 1.5, 95% CI 1.3-2.4), being a twin (OR 1.4, 95% CI 1.1-1.6), maternal age older than 40 years (OR 1.4, 95% CI 1.1-1.8) or 35-39 years (OR 1.2, 95% CI 1.1-1.4), primiparity (OR 1.2, 95% CI 1.1-1.3), and smoking (OR 1.2, 95% CI 1.1-1.3). In term infants, low Apgar scores were associated with a high risk for CP; OR 62 (95% CI 52-74) at score 6 at 5 minutes, OR 498 (95% CI 458-542) at score 3. Other factors associated with CP in term infants were breech presentation at vaginal birth (OR 3.0, 95% CI 2.4-3.7), instrumental delivery (OR 1.9, 95% CI 1.6-2.3), and emergency cesarean delivery (OR 1.8, 95% CI 1.6-2.0). Preterm birth entails a high risk for CP, but 65% of these children are born at term. Several obstetric factors and low Apgar scores are associated with CP. II-2.

A Regulatory CD4+ T Cell Subset in the BB Rat Model of Autoimmune Diabetes Expresses Neither CD25 Nor Foxp3

Biobreeding (BB) rats model type 1 autoimmune diabetes (T1D). BB diabetes-prone (BBDP) rats develop T1D spontaneously. BB diabetes-resistant (BBDR) rats develop T1D after immunological perturbations that include regulatory T cell (Treg) depletion plus administration of low doses of a TLR ligand, polyinosinic-polycytidylic acid. Using both models, we analyzed CD4+CD25+ and CD4+CD45RC- candidate rat Treg populations. In BBDR and control Wistar Furth rats, CD25+ T cells comprised 5-8% of CD4+ T cells. In vitro, rat CD4+CD25+ T cells were hyporesponsive and suppressed T cell proliferation in the absence of TGF-beta and IL-10, suggesting that they are natural Tregs. In contrast, CD4+CD45RC(-) T cells proliferated in vitro in response to mitogen and were not suppressive. Adoptive transfer of purified CD4+CD25+ BBDR T cells to prediabetic BBDP rats prevented diabetes in 80% of recipients. Surprisingly, CD4+CD45RC-CD25- T cells were equally protective. Quantitative studies in an adoptive cotransfer model confirmed the protective capability of both cell populations, but the latter was less potent on a per cell basis. The disease-suppressing CD4+CD45RC-CD25- population expressed PD-1 but not Foxp3, which was confined to CD4+CD25+ cells. We conclude that CD4+CD25+ cells in the BBDR rat act in vitro and in vivo as natural Tregs. In addition, another population that is CD4+CD45RC-CD25- also participates in the regulation of autoimmune diabetes.

Phenotypic and genetic analyses of T‐cell‐mediated immunoregulation in patients with Type 1 diabetes

To investigate the contribution of regulatory T cells and co-stimulatory molecules in CD4(+) T cells to the development of Type 1 diabetes (T1D). Twelve patients with T1D, nine patients with systemic lupus erythematosus (SLE), and 12 age-matched healthy control subjects participated. We analysed the proportions of CD25(+)CD4(+) T cells and natural killer T cells (NKT cells), and the expression levels of Foxp3, CTLA-4, CD28, ICOS, PD-1 and BTLA in peripheral blood mononuclear cells and purified CD4(+) T cells. There were no significant differences in the proportions of CD25(+) CD4(+) T cells or NKT cells among the three groups. PD-1 expression levels of peripheral CD4(+) T cells from T1D patients were significantly lower than those from healthy control subjects (P = 0.00066). In contrast, PD-1 expression levels were similar in SLE patients and healthy control subjects. The expression levels of Foxp3, CTLA-4, CD28, ICOS and BTLA were similar in the three groups. Decreased expression of the PD-1 gene in CD4(+) T cells may contribute to the development and/or maintenance of autoimmune T1D. As the population studied was small and heterogeneous, further studies are required to confirm the findings.

CD38 Is Required for the Peripheral Survival of Immunotolerogenic CD4+ Invariant NK T Cells in Nonobese Diabetic Mice

T cell-mediated autoimmune type-1 diabetes (T1D) in NOD mice partly results from this strain's numerical and functional defects in invariant NK T (iNKT) cells. T1D is inhibited in NOD mice treated with the iNKT cell superagonist alpha-galactosylceramide through a process involving enhanced accumulation of immunotolerogenic dendritic cells in pancreatic lymph nodes. Conversely, T1D is accelerated in NOD mice lacking CD38 molecules that play a role in dendritic cell migration to inflamed tissues. Unlike in standard NOD mice, alpha-galactosylceramide pretreatment did not protect the CD38-deficient stock from T1D induced by an adoptively transferred pancreatic beta cell-autoreactive CD8 T cell clone (AI4). We found that in the absence of CD38, ADP-ribosyltransferase 2 preferentially activates apoptotic deletion of peripheral iNKT cells, especially the CD4+ subset. Therefore, this study documents a previously unrecognized role for CD38 in maintaining survival of an iNKT cell subset that preferentially contributes to the maintenance of immunological tolerance.

Villous Histomorphometry and Placental Bed Biopsy Investigation in Type I Diabetic Pregnancies

Insulin-dependent diabetes mellitus (Type I) is associated with disregulation of the glucose and oxygen metabolic pathways during pregnancy, both of which affect placental villous development. Term complete placentas and placental bed biopsies, between 37 and 40 weeks, from 12 singleton pregnancies complicated by Type I diabetes were collected following delivery by elective Caesarean section. The controls consisted of 10 term placentas from uncomplicated pregnancies delivered by elective Caesarean section. Villous morphology was investigated using unbiased histomorphometric techniques, in relation to the degree of transformation of the spiral arteries and the presence of fetal macrosomia. A significant increase in fetal and placental weights, placental volume, volumes of the intervillous space and the trophoblast was found in the diabetic group compared to the controls. A significant reduction in the villous membrane specific diffusing capacity was observed between the diabetic and control groups (1.32 vs 1.72 cm3 min(-1)mmHg(-1)kg(-1), P=0.032). A significant increase in the volume of the intermediate and terminal villi, the surface area of the villi and of the fetal capillaries, and the harmonic thickness of the villous membrane was found in the macrosomic subgroup compared to the controls. There were no differences between the hypertensive subgroup with histological evidence of partial transformation of the spiral arteries and the controls. These data indicate that placental development in insulin-dependent diabetic pregnancies is affected differentially when pregnancies complicated by fetal macrosomia are separated from those complicated by maternal hypertensive disorders with partial transformation of the spiral arteries. The reduction in the specific diffusing capacity of the villous membrane may contribute to the fetal hypoxia and increased fetal and neonatal morbidity associated with diabetes.

Control of Type 1 Autoimmune Diabetes by Naturally Occurring CD4+CD25+Regulatory T Lymphocytes in Neonatal NOD Mice

Nonobese diabetic (NOD) mice serve as a model of spontaneous type 1 diabetes (T1D), a T cell-mediated autoimmune disease leading to the destruction of pancreatic insulin-producing beta islet cells. A possible deficiency in regulatory T (T(reg)) cell development or function may promote the activation, expansion, and recruitment of autoreactive T cells and the onset of T1D. Naturally occurring CD4(+)CD25(+) T(reg) (nT(reg)) cells, which typically display potent inhibitory effects on T cell functions in vitro and in vivo, may be defective at controlling autoimmunity in T1D. We have examined the relative contribution of CD4(+)CD25(+) nT(reg) cells in the immune regulation of T1D in the NOD mouse model. CD4(+)CD25(+) T cells represent 5-10% of CD4(+) thymocytes or peripheral T cells from prediabetic neonatal NOD mice, are anergic to TCR signals, and potently suppress activated T cells in a contact-dependent and cytokine-independent fashion in vitro. Unlike total CD4(+) T cells, prediabetic CD25(+)-depleted CD4(+) T cells are potently diabetogenic when transferred in immunodeficient NOD mice. Co-transfer of CD4(+)CD25(+) T cells from thymocytes or peripheral lymphoid tissues of neonatal NOD mice dramatically halts disease development and beta-islet cell lymphocytic infiltration, even when T1D is induced by CD4(+) T cells from BDC2.5 transgenic or diabetic NOD mice. Finally, we show that CD4(+)CD25(+) T(reg) preferentially accumulate in inflamed pancreatic environments, where they potently inhibit the antigen-specific expansion and cytokine effector functions of diabetogenic T cells. Thus, CD4(+)CD25(+) T cell-mediated regulation is operative in the prediabetic neonatal T cell repertoire and can suppress the diabetogenic process and control the onset of T1D.

Unraveling the Pathogenesis of Type 1 Diabetes with Proteomics: Present And Future Directions

Type 1 diabetes (T1D) is the result of selective destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. T1D is due to a complex interplay between the beta-cell, the immune system, and the environment in genetically susceptible individuals. The initiating mechanism(s) behind the development of T1D are largely unknown, and no genes or proteins are specific for most T1D cases. Different pro-apoptotic cytokines, IL-1 beta in particular, are present in the islets during beta-cell destruction and are able to modulate beta-cell function and induce beta-cell death. In beta-cells exposed to IL-1 beta, a race between destructive and protective events are initiated and in susceptible individuals the deleterious events prevail. Proteins are involved in most cellular processes, and it is thus expected that their cumulative expression profile reflects the specific activity of cells. Proteomics may be useful in describing the protein expression profile and thus the diabetic phenotype. Relatively few studies using proteomics technologies to investigate the T1D pathogenesis have been published to date despite the defined target organ, the beta-cell. Proteomics has been applied in studies of differentiating beta-cells, cytokine exposed islets, dietary manipulated islets, and in transplanted islets. Although that the studies have revealed a complex and detailed picture of the protein expression profiles many functional implications remain to be answered. In conclusion, a rather detailed picture of protein expression in beta-cell lines, islets, and transplanted islets both in vitro and in vivo have been described. The data indicate that the beta-cell is an active participant in its own destruction during diabetes development. No single protein alone seems to be responsible for the development of diabetes. Rather the cumulative pattern of changes seems to be what favors a transition from dynamic stability in the unperturbed beta-cell to dynamic instability and eventually to beta-cell destruction.

Structural model of human GAD65: Prediction and interpretation of biochemical and immunogenic features

The 65 kDa human isoform of glutamate decarboxylase, GAD65, plays a central role in neurotransmission in higher vertebrates and is a typical autoantigen in several human autoimmune diseases, such as insulin-dependent diabetes mellitus (IDDM), Stiff-man syndrome and autoimmune polyendocrine syndrome type I. In autoimmune diabetes, an attack of inflammatory cells to endocrine pancreatic beta-cells leads to their complete destruction, eventually resulting in the inability to produce sufficient insulin for the body's requirements. Even though the etiology of beta-cell destruction is still a matter of debate, the role and antigenic potency of GAD65 are widely recognized. Herein a model of GAD65 is presented, which is based on the recently solved crystal structures of mammalian DOPA decarboxylase and of bacterial glutamate decarboxylase. The model provides for the first time a detailed and accurate structure of the GAD65 subunit (all three domains) and of its dimeric quaternary assembly. It reveals the structural basis for specific antibody recognition to GAD65 as opposed to GAD67, the other human isoform, which shares 81% sequence similarity with GAD65 and is much less antigenic. Literature data on monoclonal antibody binding are perfectly consistent with the detailed features of the model, which allows explanation of several findings on GAD65 immunogenicity. Importantly, by analyzing the active site, we identified the residues most likely involved in catalysis and substrate recognition, paving the way for rational mutagenesis studies of the GAD65 reaction mechanism, specificity and inhibition.

Is TAP2*0102 allele involved in insulin-dependent diabetes mellitus (type 1) protection?

In this study, we have investigated the frequencies of TAP1 and TAP2 alleles in a group of 226 persons, living in La Reunion Island, consisting of 70 patients with insulin-dependent diabetes mellitus (IDDM) and most of their first degree relatives ( i.e., 156 parents and full sibling subjects) and previously HLA DQB1, DQA1, and DRB1 genotyped. The population of this island is constituted by a particular structure of highly crossbreeding people. Interestingly, the new TAP2*0104 allele, previously discovered by our team in Reunion Island, was found to be increased in the IDDM population and the calculated HRR was relatively high (HRR = 3.3). This result seems to be due to a positive linkage disequilibrium between TAP2*0104 allele and the highly diabetogenous DQB1* 0201–DQA1* 0501–DRB1 0301 haplotype (HRR = 9), which suggests that TAP2*0104 cannot be considered as an additional predispositional factor, but more as a genetic susceptibility marker of IDDM. In addition, we show that minor alleles (TAP2D, *0102, *0103, *0104) are associated with a restricted number of HLA DQ-DR haplotypes and each of them exhibits a preferential linkage with one particular haplotype. In contrast with other alleles, and despite a HRR value close to 1, we show that TAP2*0102 allele contributes significantly to a drastic reduction of the diabetogenic effect of DQB1*0201–DQA1*0301.1–DRB*0701 haplotype. Indeed, this haplotype, which is usually preferentially transmitted to affected children, is dominantly transmitted to healthy children when it is associated with TAP2*0102. Therefore, this allele seems to contribute to genetic protection to IDDM.

Histomorphometric evaluation of the influence of the diabetic metabolic state on bone defect healing depending on the defect size in spontaneously diabetic BB/OK rats

Insulin-dependent type 1 diabetes mellitus (IDDM) has been shown to alter the properties of bone and impair bone repair in both humans and animals. The objective of this study was the detailed histomorphometric evaluation of the influence of the diabetic metabolic state on bone formation and remodeling during bone defect healing depending on the defect size in spontaneously diabetic BB/O(ttawa)K(arlsburg) rats, a rat strain that represents a close homology to IDDM in man. Based on blood-glucose values at the time of surgery, postoperative blood-glucose course, and postoperative insulin requirements, 80 spontaneously diabetic BB/OK rats were divided into groups with well-compensated or poorly compensated metabolic state. Forty LEW.1A rats served as normoglycemic controls. Using a Kirschner wire, bone defects of different sizes were created proximal to the knee joint space in both femora. Ten animals from each group were killed on postoperative days 7, 14, 24, and 42, and specimens were processed undecalcified for quantitative bone histomorphometry. In terms of bone histomorphometry, our study did not show any differences in bone defect healing between the groups where the defect size was 0.4 mm. Larger bone defects (0.8 mm) only showed significant differences in the structural calculations after the 24th postoperative day exclusively in poorly compensated diabetic rats compared to well-compensated diabetic and control rats ( P < 0.05 or P < 0.01). In bone defect sizes more than 1.2 mm, severe mineralization disorders occurred within the first 14 days exclusively in rats with poorly compensated diabetic metabolic state with a highly significant ( P < 0.001) or significant ( P < 0.01) decrease of all fluorochrome-based parameters of mineralization, apposition, formation, and timing of mineralization in comparison to spontaneously diabetic rats with well-compensated diabetic metabolic state and control rats. These results demonstrate that the bone repair of minor bone defects (0.4 mm) is independent of the diabetic metabolic state in spontaneously diabetic BB/OK rats. In larger bone defects (more than 0.8 mm), the bone defect healing in spontaneously diabetic BB/OK rats is impaired exclusively in poorly compensated diabetic metabolic states. This study suggests that strictly controlled insulin treatment resulting in a well-compensated diabetic metabolic state will ameliorate the impaired histomorphometric parameters of IDDM bone defect healing.

Improving metabolic control reverses the histomorphometric and biomechanical abnormalities of an experimentally induced bone defect in spontaneously diabetic rats.

Insulin-dependent type 1 diabetes mellitus (IDDM) has been shown to alter the properties of bone and to impair fracture-healing in both humans and animals. The objective of this study was to examine changes in the histomorphometric and mechanical parameters of bone and remodeling during bone-defect healing, depending on the diabetic metabolic state in spontaneously diabetic BB/O(ttawa)K(arlsburg) rats, a rat strain that represents a close homology to IDDM in humans. A standardized bone-defect model was chosen and based on blood-glucose values at the time of surgery (mg%), postoperative blood-glucose course (mg%), and postoperative insulin requirements (IU/kg). A total of 120 spontaneously diabetic BB/OK rats were divided into groups with a well-compensated (n = 60; 169 +/- 102 mg%; 230 +/- 126 mg%; and 2.2 +/- 1.1 IU/ kg) or poorly compensated (n = 60; 380 +/- 159 mg%; 359 +/- 89 mg%; and 5.4 +/- 1.1 IU/kg) metabolic state. Sixty LEW.1A rats served as the normoglycemic controls (93 +/- 19 mg%). Fifteen animals from each group were killed on postoperative days 7, 14, 24, and 42, and specimens were processed undecalcified for quantitative bone histomorphometry and for biomechanical testing. Our study showed in terms of bone histomorphometry, within the first 14 days, that severe mineralization disorders occurred exclusively in the rats with a poorly compensated diabetic metabolic state with a highly significant (P < 0.001) or significant (P < 0.01) decrease of all fluorochrome-based parameters of mineralization, apposition, formation and timing of mineralization, as well as significantly decreased values of biomechanical properties (P < 0.05) in comparison to the spontaneously diabetic rats with a well-compensated metabolic state and to the control rats. Bone-defect healing in spontaneously diabetic BB/ OK rats is retarded exclusively in a poorly compensated diabetic metabolic state. This study suggests that strictly controlled insulin treatment resulting in a well-compensated diabetic metabolic state will ameliorate the impaired early and late parameters of IDDM bone-defect healing.

Oxidative and antioxidative status in pregnant women with either gestational or type 1 diabetes

Objectives: To evaluate oxidative and antioxidative status in pregnant diabetic women between 26 and 32 weeks of gestation. Design and Methods: Free and total malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX), and vitamins A and E were determined in plasma and erythrocytes of 54 pregnant women. Among these, 27 were diabetics with either gestational diabetes mellitus (GDM), sub-group I, or previous insulin-dependent diabetes mellitus (type 1 diabetes), sub-group II. The other 27 patients were controls. Fasting plasma glucose and HbA 1c levels were determined in all women. Results: HbA 1c levels, plasma-, and erythrocyte-free MDA levels were significantly higher in all diabetic women and in both sub-groups than in controls. Plasma vitamin E and erythrocyte vitamin A levels were significantly lower in all diabetic women than in controls. Moreover, GPX and SOD activities were significantly reduced in all diabetic women, GPX in both sub-groups and SOD only in type 1 diabetes. Conclusions: The increased oxidative stress we demonstrated in pregnant women with previous type 1 diabetes or with GDM should be monitored by strictly controlling blood glucose during pregnancy with stringent recommendations and perhaps antioxidant supplementation.

Microalbuminuria in diabetes mellitus: Efficacy of a new screening method in comparison with timed overnight urine collection

Diabetic nephropathy and end-stage renal failure are still a major cause of mortality amongst patients with diabetes mellitus (DM). In this study, we evaluated the Clinitek-Microalbumin (CM) screening test strip for the detection of microalbuminuria (MA) in a random morning spot urine in comparison with the quantitative assessment of albuminuria in the timed overnight urine collection (“gold standard”). One hundred thirty-four children, adolescents, and young adults with insulin-dependent DM Type 1 were studied at 222 outpatient visits. Because of urinary tract infection and/or haematuria, the data of 13 visits were excluded. Finally, 165 timed overnight urine were collected in the remaining 209 visits (79% sample per visit rate). Ten (6.1%) patients presented MA of ≥15 μg/min. In comparison however, 200 spot urine could be screened (96% sample/visit rate) yielding a significant increase in compliance and screening rate ( P<.001, Mc Nemar test). Furthermore, at 156 occasions, the gold standard and CM could be directly compared. The sensitivity and the specificity for CM in the spot urine (cut-off ≥30 mg albumin/l) were 0.89 [95% confidence interval (CI) 0.56–0.99] and 0.73 (CI 0.66–0.80), respectively. The positive and negative predictive value were 0.17 (CI 0.08–0.30) and 0.99 (CI 0.95–1.00), respectively. Considering CM albumin-to-creatinine ratio, the results were poorer than with the albumin concentration alone. Using CM instead of quantitative assessment of albuminuria is not cost-effective (US$35 versus US$60/patient/year). In conclusion, to exclude MA, the CM used in the random spot urine is reliable and easy to handle, but positive screening results of ≥30 mg albumin/l must be confirmed by analyses in the timed overnight collected urine. Although the screening compliance is improved, in terms of analysing random morning spot urine for MA, we cannot recommend CM in a paediatric diabetic outpatient setting because the specificity is far too low.

Increased transvascular low density lipoprotein transport in insulin dependent diabetes: a mechanistic model for development of atherosclerosis

Background: The increased risk of atherosclerosis associated with diabetes cannot be explained by conventional cardiovascular risk factors alone. We hypothesized that transvascular lipoprotein transport may be increased in patients with diabetes, possibly explaining increased intimal lipoprotein accumulation and thus atherosclerosis. Methods: We used an in vivo method for measurement of transvascular transport of low density lipoprotein (LDL) and applied it in 24 patients with insulin dependent diabetes mellitus (type 1) and in 30 healthy controls. LDL was individually sampled and autologous 131-iodinated LDL was reinjected intravenously in addition to 125-iodinated albumin, and the 1-h fractional escape rates were taken as indices of transvascular transport. Results: Transvascular LDL transport was 5.7±2.2 and 4.0±1.8%/h in patients with diabetes and controls ( P<0.005); equivalent values for albumin were 6.8±2.5 and 5.4±2.0%/h ( P<0.05). This difference most likely was not caused by altered hepatic LDL receptor expression, glycosylation of LDL, small LDL size, nephropathy, statin use, or different plasma insulin levels in diabetes patients. Conclusion: Transvascular LDL transport may be increased in patients with type 1 diabetes. This suggests that lipoprotein flux into the arterial wall is increased in people with type 1 diabetes, possibly explaining accelerated development of atherosclerosis.