Insulin-dependent Diabetes Mellitus Subjects Research Articles

Adaptation to Protein Restriction Is Impaired in Insulin-Dependent Diabetes Mellitus ,

Although mild abnormalities of amino acid metabolism frequently exist in conventionally treated insulin-dependent diabetes mellitus (IDDM), their physiologic and nutritional importance is uncertain. We tested whether a tendency toward body N loss can be either masked or revealed in insulin-treated IDDM by changing the level of protein in the diet. After adaptation to a protein-free diet adequate in all other nutrients, obligatory urinary N excretion of intensively treated IDDM subjects was significantly greater than normal, indicating an impaired ability to recycle endogenous amino acids during protein restriction. When the preceding diet was high in protein, urea N production after consumption of a mixed test meal matched the amount of N consumed for both normal and diabetic subjects. However, when the test meal was preceded by 5 d of protein restriction, conventionally treated IDDM subjects failed to adaptively reduce postprandial urea production as effectively as normal or intensively treated IDDM subjects. Thus, even during insulin treatment, the ability to maximally recycle endogenous amino acids is impaired in IDDM, as is the ability to adaptively increase dietary amino acid retention in response to protein restriction.

Characterization of Insulin Adsorption Behavior of Dialyzer Membranes Used in Hemodialysis

Although it has been reported that plasma insulin is removed by hemodialysis (HD), the mechanism for this has not been elucidated. We investigated the mechanism of insulin removal during HD treatment and the characteristics of insulin removal with three high-flux membranes. In our in vivo study, 20 stable diabetic patients on HD were randomly selected for three HD sessions with three different membranes: polysulfone (PS), cellulose triacetate (CTA), and polyester polymer alloy (PEPA). Blood samples were obtained from the blood tubing at the arterial (A) site at the beginning and end of the sixth HD session to investigate insulin reduction in patients. At 1 h after the initiation of dialysis, blood samples were obtained from both the A and venous sites of the dialyzer to investigate the insulin clearance with the different membranes. There was a significant reduction in patients' plasma insulin at each time point with each of the three membranes. The insulin clearance with the PS membrane was significantly higher than that with the CTA and PEPA membranes. Although no difference was observed in the plasma insulin reduction rate between the three membranes in the total subject group, there was a significantly higher reduction rate with the PS membrane in insulin-dependent diabetes mellitus subjects. The clearance of insulin in in vitro tests was significantly higher with the PS and PEPA membranes than with the CTA membrane in both new and clinically used dialyzers. Insulin was not detected in the dialysate or ultrafiltration fluids in either the in vivo or in vitro studies. The mechanism of plasma insulin clearance by HD is mainly by adsorption, and the amount of insulin adsorbed differed depending on the dialyzer membrane used.

Complement-dependent antibody mediated cytotoxicity (C'AMC) in patients with newly diagnosed insulin-dependent diabetes mellitus.

Serum activities of complement-dependent antibody mediated cytotoxicity (C'AMC) were determined in 36 consecutive patients with newly diagnosed insulin-dependent diabetes mellitus (IDDM). The sequential exposure of 51Cr labeled neonatal rat islet cells to patient serum and rabbit complement revealed the presence of C'AMC in 28 IDDM subjects. The C'AMC titres ranged between 1:4 and 1:512 and were not related to the C'AMC activity of a given sample as measured at a standard dilution (1:4). In comparison to the clinical characteristics of 21 IDDM patients with negative C'AMC, higher C'AMC titres (greater than or equal to 1:32) were associated with a lower mean age at diagnosis of IDDM (12.2 +/- 2.1 vs. 19.0 +/- 2.3 years; p less than 0.05), with a higher frequency of infections up to 6 months prior to diagnosis (6 out of 11 vs. 3 out of 21 patients; p less than 0.05) and, although statistically not significant, a preponderance of female sex together with a decreased frequency of HLA-DR4. In contrast, fasting C-peptides levels, HLA-DR3 antigen frequency and Coxsackie B1-6 virus antibody titres were not related to the C'AMC titres. It is concluded that (1) C'AMC titration is superior to the detection of initial C'AMC levels for evaluating the strength of the complement-dependent humoral immune response towards islet cell surface (auto)antigen(s), and (2) infectious agents may be involved in eliciting a C'AMC response.

Circulating acylated and total ghrelin and galanin in children with insulin‐treated type 1 diabetes: relationship to insulin therapy, metabolic control and pubertal development

To study the circulating levels of two gut-derived peptides in children with type 1 (insulin-dependent) diabetes mellitus (IDDM). Plasma levels of ghrelin, both total ghrelin (TG) and the acylated form (AG), and galanin and their relationships with insulin dosage, metabolic control, IGFBP-1, body mass and pubertal development were evaluated in 91 children, aged 11.1 +/- 2.7 years, affected by IDDM and treated with insulin. Ninety-one healthy children were selected as controls. Body mass index (BMI)-adjusted levels of both forms of ghrelin were reduced in IDDM compared with healthy subjects, with greater values in prepubertal than pubertal IDDM subjects. A negative association was found between AG and fasting insulin serum levels and insulin resistance [measured by using the homeostasis model assessment of insulin resistance (HOMA IR)] among the healthy children. IDDM children showed a negative association of their plasma ghrelin (both acylated and total) with daily insulin dosage, and the three adiposity indices (BMI, skinfold thickness and percentage fat mass). IGFBP-1 levels were higher among the IDDM children without any association with ghrelin serum values. BMI-adjusted plasma levels of galanin were higher among IDDM compared to healthy subjects, irrespective of sex or pubertal development. Greater values for galanin were found among pubertal than prepubertal subjects in both groups without any significant differences between the genders. A positive association was found between galanin and BMI in both groups and between galanin and haemoglobin A1c (HbA1c) among the IDDM children. No relationship existed between either galanin and fasting serum insulin among the healthy subjects or galanin and both insulin dosage or duration of treatment among the IDDM subjects. The associations found between both ghrelin and galanin with adiposity indices could be considered as an indirect signal of involvement of the two peptides in the development of the nutritional status of the IDDM adolescents. The reduction in both forms of ghrelin could be involved in the development of the body mass increase of IDDM subjects with opposite effects, either influencing insulin sensitivity or exerting a compensatory restraint of feeding.

Effect of protein restriction on sulfur amino acid catabolism in insulin-dependent diabetes mellitus.

Persons with conventionally treated insulin-dependent diabetes mellitus (IDDM) appear to be impaired in their ability to reduce fed-state urea production appropriately in response to dietary protein restriction (Hoffer LJ, Taveroff A, and Schiffrin A. Am J Physiol 272: E59-E67, 1997). To determine whether these conclusions apply to whole body sulfur amino acid (SAA) catabolism, we used samples from this protocol to measure daily urinary sulfate excretion and fed-state sulfate production after a high-protein test meal before and after dietary protein restriction. Eight normal subjects and six IDDM subjects treated with twice-daily intermediate- and short-acting insulin consumed a mixed test meal containing 0.50 g protein/kg after adaptation to 4 days of high protein intake (1.28 g protein/kg body wt) and again after 5 days of dietary protein restriction (0.044 g/kg). Adaptation to protein restriction decreased daily urinary sulfate and urea-N excretion by approximately 80%. Over the first 24 h of protein restriction, urinary sulfate excretion decreased more than urea-N excretion for both the normal and IDDM subjects. Under conditions of a high prior protein intake, fed-state sulfate production was normal for the IDDM subjects; protein restriction reduced fed-state sulfate production by 51% (normal subjects) and 59% (IDDM subjects; not significant). We conclude that whole body SAA metabolism is normal in conventionally treated IDDM before and after dietary protein restriction. SAA catabolism, as measured by fed-state sulfate production, may be a convenient and useful method to determine the extent of whole body protein dysregulation in IDDM.

Vestibulo-ocular, optokinetic and postural function in diabetes mellitus.

We compared vestibulo-ocular reflex, optokinetic reflex and postural function in subjects with insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM), as well as non-diabetic controls. Both IDDM and NIDDM subjects exhibited significant deficits in gaze-holding in darkness (p < 0.05), small changes in vestibulo-ocular reflex (VOR) phase re velocity (p < 0.005) without a change in VOR gain, and a decrease in optokinetic reflex (OKR) slow phase velocity (p < 0.001). In addition, a smaller decrease was found in OKR quick phase amplitude (p < 0.02); postural sway was increased in both diabetic groups (p < 0.05), although this was not specific to the conditions of the Clinical Test of Sensory Interaction and Balance (CTSIB) that test vestibular contributions to postural stability. No differences were found in optokinetic afternystagmus or latency to circularvection. These results suggest that both IDDM and NIDDM are associated with deficits in gaze-holding, VOR and OKR function.

Oxidative stress indices in IDDM subjects with and without long-term diabetic complications

Background: Numerous animal and population studies of diabetes have identified markers of oxidative stress. However, for most markers that have been measured the results are not consistent. In addition, it is less clear whether oxidative stress is related to the development of diabetic complications. The objective of this study was to evaluate a series of plasma markers and leukocyte markers to test the hypothesis that type 1 Insulin Dependent Diabetes Mellitus (IDDM) subjects experience oxidative stress. A related question was whether markers of oxidative stress are higher in IDDM subjects who have developed long-term complications. Methods: The study population consisted of 22 IDDM subjects with diabetic complications and 22 IDDM subjects without complications, both groups matched by age and gender and with similar HbA1c levels, and 16 nondiabetic control subjects. Plasma levels of organoperoxides were determined by the ferrous oxidation/xylenol orange (FOX) assay, malondialdehyde by the thiobarbituric acid (TBARS) assay, and vitamin E by HPLC. Mononuclear cells and polymorphonuclear cells were analyzed for ascorbic acid by HPLC and for glutathione (GSH) by enzymatic recycling. In addition, GSH peroxidase, GSH transferase and glucose-6-phosphate dehydrogenase levels were determined in both cell fractions. Results: Plasma organoperoxides were significantly elevated in the IDDM subjects compared to controls ( p = 0.02) while TBARS and vitamin E levels were not significantly different. In the IDDM subjects, mononuclear cell levels of ascorbic acid were significantly lower ( p < 0.02) and levels of GSH were lower, approaching significance ( p = 0.07), compared to controls. Ascorbic acid and GSH levels in polymorphonuclear cells were not significantly different between IDDM subjects and controls, nor were enzyme levels different. In addition, the plasma and intracellular indices of oxidative status in IDDM subjects were not different when IDDM subjects with complications were compared to IDDM subjects without complications. Conclusion: Demonstration of oxidative stress in IDDM subjects depends upon which markers are measured. This is in agreement with previous studies of oxidative stress in various disease states including diabetes. Plasma levels of organoperoxides may be the most reliable indicators of oxidative stress. However, it is unclear whether elevated plasma organoperoxides indicate a generalized systemic stress or are produced in localized areas. By comparison, oxidative stress indices determined with isolated blood cells may provide a clearer picture. Depressed levels of ascorbic acid and GSH were observed only in mononuclear cells, which are mainly long-lived T lymphocytes. Mononuclear cells antioxidant status may reflect systemic oxidative stress. In this study, neither plasma markers nor intracellular markers of oxidative stress were different in IDDM subjects with long-term diabetic complications compared to subjects without complications.

The C825T polymorphism in the G-protein beta3 subunit gene and diabetic complications in IDDM patients.

Complications of insulin-dependent diabetes mellitus (IDDM) are a major cause of morbidity and mortality; however, the mechanisms of their development are still to be elucidated. Genetic susceptibility contributes to the pathogenesis of nephropathy in IDDM. Enhanced G-protein activation, a cellular phenotype observed in cultured cells from patients with essential hypertension, was recently documented in IDDM subjects with nephropathy. A C825T polymorphism was recently described in GNB3, the gene encoding the beta 3 subunit of heterotrimeric G-proteins. This genetic variant has been associated with enhanced G-protein activation. The 825T allele was observed more frequently in a group with essential hypertension. We analyzed the role of the C825T polymorphism in the predisposition to diabetic complications in IDDM. In this study, we investigated the frequency of this polymorphism in a large case-control study and found no association of the 825T allele with diabetic nephropathy, retinopathy, and neuropathy.

L-selectin gene T668C mutation in type 1 diabetes patients and their first degree relatives

There have been some studies published recently which have suggested that L-selectin and/or other adhesion molecules could be the new markers for diabetes type 1 risk development in humans and animal models of the disease. The alterations of soluble L-selectin have been found not only in overt but also in the preclinical stage of disease development and were independent from the presence of ICA — a marker of ongoing autoimmunity, but associated with HLA related genetic predisposition to insulin-dependent diabetes mellitus (IDDM). The aim of our study was to evaluate the frequency of the L-selectin gene T668C mutation (from thymine to cytosine at position 668) resulted in F206L an amino acid substitution in patients with overt diabetes and their unaffected first degree relatives in comparison to the unselected control population. In the unaffected siblings of IDDM subjects we have observed a significantly higher frequency of the L-selectin gene T668C mutation in comparison to their relatives with type 1 diabetes and healthy controls. It was also shown that there is an association between T668C mutation and low HLA related risk of IDDM development, the highest frequency of F206L mutation in the EGF domain of L-selectin was observed in relatives with ‘protective’ HLA DQB1*0602 allele and nonDRB1*03-nonDRB1*04 haplotype, while in subjects with highest risk of IDDM haplotype the frequency of T668C mutation was similar to the controls. We would like to hypothesise that the T668C L-selectin gene mutation could have a (protective?) role in the development of IDDM, but further studies concerning their role in type 1 diabetes are needed.

Renal resistance to vasopressin in poorly controlled type 1 diabetes mellitus.

To investigate the hypothesis that diabetes induces nephrogenic diabetes insipidus, we studied the urine-concentrating ability in response to vasopressin (AVP) in 12 patients with insulin-dependent diabetes mellitus (IDDM) and 12 nondiabetic controls. Subjects were euglycemic-clamped, and after oral water loading, AVP was infused intravenously for 150 min. AVP induced a greater (P<0.001) rise in urine osmolality in controls (67.6+/-10.7 to 720+/-31.1 mosmol/kg, P<0.001) than in IDDM patients (64.3+/-21.6 to 516.7+/-89.3 mosmol/kg, P<0.001). Urinary aquaporin-2 concentrations after AVP infusion were higher in controls (611.8+/-105.6 fmol/mg creatinine) than in IDDM (462.0+/-94.9 fmol/mg creatinine, P = 0. 003). Maximum urine osmolality in IDDM was inversely related to chronic blood glucose control, as indicated by Hb A(Ic) (r = -0.87, P = 0.002). To test the hypothesis that improved glycemic control could reverse resistance to AVP, 10 IDDM subjects with poor glycemic control (Hb A(Ic) >9%) were studied before (B) and after (A) intensified glycemic control. Maximum urine osmolality in response to AVP increased with improved glycemic control (B, 443.8+/-49.0; A, 640.0+/-137.2 mosmol/kg, P<0.001), and urinary aquaporin-2 concentrations after AVP increased from 112.7 +/-69 to 375+/-280 fmol/mg creatinine (P = 0.006), with improved glycemic control. Poorly controlled IDDM is associated with reversible renal resistance to AVP.

Levels of peripheral blood cell DNA damage in insulin dependent diabetes mellitus human subjects

Increased production of reactive oxygen species (ROS) in vivo can lead to cellular biomolecule damage. Such damage has been suggested to contribute to the pathogenesis of insulin dependent diabetes mellitus (IDDM). In this study, we used the alkaline comet assay to measure DNA damage (single-stranded DNA breaks and alkali-labile sites) in freshly isolated whole blood, lymphocytes, monocytes, and neutrophils from 23 subjects with IDDM and 32 age- and sex-matched controls. Analysis of the results showed elevated levels of DNA damage (expressed as % comet tail DNA) in the lymphocyte (4.10±0.47, 3.22±0.22), monocyte (4.28±0.47, 3.49±0.18), and whole blood (4.93±0.51, 4.51±0.23) fractions from IDDM subjects compared to controls, respectively, but the increases observed were not statistically significant. However, we found significantly elevated basal levels of DNA damage in the neutrophil fraction (8.38±0.64, 4.07±0.23; p<0.001, Mann–Whitney U test) in IDDM subjects compared to controls. Given these novel neutrophil findings, we extended the study to include a total of 50 IDDM subjects and 50 age- and sex-matched control subjects and determined basal levels of DNA damage in the neutrophils of all 100 subjects. We found significantly elevated mean levels of DNA damage (8.40±0.83, 4.34±0.27; p<0.001, Mann–Whitney U test) in the neutrophils from the IDDM subjects when compared to controls. Our results show that even with acceptable glycaemic control there is a significantly elevated level of DNA damage within diabetic neutrophils in vivo.

Insulin-dependent diabetes mellitus and oral soft tissue pathologies. II. Prevalence and characteristics of Candida and candidal lesions

To assess the prevalence of Candida albicans and oral infection with Candida in patients with insulin-dependent diabetes mellitus (IDDM). This cross-sectional study compared the prevalence of candidiasis in 405 subjects with IDDM and 268 nondiabetic control subjects. Assessments included evidence of clinical manifestations of candidiasis and a quantitative measure of Candida pseudohyphae in a cytologic smear from the midline posterior dorsal tongue. More subjects with IDDM than control subjects without IDDM (15.1% vs 3.0%) were found to have clinical manifestations of candidiasis, including median rhomboid glossitis, denture stomatitis, and angular cheilitis. IDDM subjects were also more likely to have any Candida pseudohyphae in their cytologic smears (23.0% vs 5.7%; P <.0001), as well as pseudohyphae counts of >10/cm(2) (7.1% vs 0.8%; P <.0001). Diabetic subjects with median rhomboid glossitis were more likely to have a longer duration of IDDM and complications of nephropathy and retinopathy. Denture stomatitis was associated with smoking, retinopathy, higher Candida counts, poor glycemic control, and longer duration of IDDM. A multivariate regression analysis found 3 factors to be significantly associated with the presence of Candida pseudohyphae in the subjects with IDDM: current use of cigarettes (odds ratio, 2:4), use of dentures (odds ratio, 2:3), and elevated levels of glycosylated hemoglobin (odds ratio, 1:9). The use of antimicrobials, immunosuppressants, or drugs with xerostomic side effects was not related to the presence of Candida. Candida pseudohyphae and oral soft tissue manifestations of candidiasis were more prevalent in subjects with IDDM than in control subjects without diabetes. The presence of Candida pseudohyphae was significantly associated with cigarette smoking, use of dentures, and poor glycemic control.

The analysis of in vitro transforming growth factor-β1 (TGF-β1) production by peripheral blood in overt and pre-clinical type 1 diabetes mellitus

The alterations of TGF-β1 production are believed to contribute to the development of insulin-dependent diabetes mellitus (IDDM) in animal models as well as in humans. There is also increasing evidence about the role of this cytokine in the pathogenesis of diabetic vascular complications. The aim of our study was to evaluate in vitro TGF-β1 production by peripheral blood of newly diagnosed type 1 diabetes patients and subjects in the pre-clinical stage of the disease in comparison to healthy controls and relatives of IDDM patients with low genetic risk for diabetes development. The study was carried out in three groups of subjects: 22 patients with a recently diagnosed type 1 diabetes, their 24 first degree relatives with a different genetic risk of IDDM development and 18 healthy volunteers (control group). In all studied groups whole blood was taken for morphology parameters, HbA 1C and for 72 h cultures with PHA stimulation for the estimation of TGF-β1 in vitro production. TGF-β1 concentration in supernatants were quantified by ELISA. In the first degree relatives HLA typing (for DR3, DR4 and DQB1*0602 alleles), measurements of anti-pancreatic antibodies (ICA, GADA, IA-2A, IAA) and intravenous glucose tolerance tests were performed. The levels of TGF-β1 in the supernatants were significantly higher in diabetic patients ( P<0.0002) and in their first degree relatives ( P<0.05) in comparison to the control group. In the group of first degree relatives TGF-β1 levels were highest in subjects with the presence of two or more pancreatic autoantibodies and/or with impaired insulin release in IVGTT, but lowest in relatives with protective DQB1*0602 alleles ( P<0.01). There was also a significant positive correlation between the TGF-β1 levels and HbA 1C in the IDDM subjects and first degree relatives ( P<0.03). Our study suggests that the alterations of TGF-β1 levels could be associated with the activity of autoimmune process leading to pancreatic B cells destruction and may have a role in the pathogenesis of diabetic complications, but further studies in humans are needed.

LINKAGE DISEQUILIBRIUM TESTING OF FOUR INTERLEUKIN-1 GENE-CLUSTER POLYMORPHISMS IN DANISH MULTIPLEX FAMILIES WITH INSULIN-DEPENDENT DIABETES MELLITUS

The molecules of the interleukin 1 (IL-1) system have been suggested to play a role in the pathogenesis of insulin-dependent diabetes mellitus (IDDM), and polymorphisms in the genes encoding IL-1β (IL1B), the IL-1 Type 1 receptor (IL1RTI) and the IL-1 receptor antagonist (IL1RN) molecules have been associated with IDDM in case–control studies. It can be difficult to exclude selection biases in case–control studies leading to spurious association. This risk is eliminated when using the transmission disequilibrium test (TDT). Hence, by means of the TDT we have investigated four intragenic IL-1 gene-cluster polymorphisms, the IL1B AvaI, the IL1B TaqI, the IL1RTI PstI and the IL1RN 2ndintron polymorphisms, for linkage and intra-familial association with IDDM in Danish IDDM multiplex family material comprising 245 families. We found no evidence for overall linkage or intra-familial association between any of the polymorphisms and IDDM. In addition, we did not find linkage between any of the polymorphisms and IDDM in HLA-DR3/4 heterozygous or HLA-non-DR3/4 heterozygous IDDM subjects, respectively. In conclusion, by means of intra-familial TDT analysis we found no linkage or intra-familial association between IDDM and the four IL-1 gene-cluster polymorphisms in Danish IDDM multiplex family material.

High Frequency of HLA-DQB1 Non-Asp57 Alleles in Kuwaiti Children with Insulin-Dependent Diabetes mellitus

The prevalence of polymorphic amino acids at position 57 of the HLA DQB1 in Kuwaiti children with insulin-dependent diabetes mellitus (IDDM) and nondiabetic controls has been determined using a polymerase chain reaction-sequence-specific primers (PCR-SSP) method. Using this approach, 34/55 (62%) IDDM children were found to be homozygous Ala/Ala and 19/55 (35%) were heterozygous with various combinations. Amongst the IDDM children with heterozygous genotype at codon 57 of HLA DQB1, 6/55 (11%) had Asp/Ala, 8/55 (15%) had Ala/Val, 4/55 (7%) had Ala/Ser and 1/55 had Asp/Val allelic combinations. When considered collectively, the nonaspartate (NA) alleles were represented in 87% of the IDDM cases and only 13% cases had Asp⁵⁷ allele in different heterozygous combinations, while none of the IDDM subjects had a homozygous Asp genotype. In nondiabetic controls, homozygous non-Asp (NA) alleles were represented in 44% subjects, 37% of the controls were heterozygous (NA/A) and 19% had a homozygous (A/A) genotype. These differences between the IDDM group and the control group were found to be statistically significant. Our data report one of the highest frequency of NA/NA residues at this locus compared with that from different world populations (Sardinians, Norwegians, US Caucasians, US Blacks and Chinese).

Anger State During Acute Insulin-Induced Hypoglycaemia

McCRIMMON, R. J., F. M. E. EWING, B. M. FRIER AND I. J. DEARY. Anger state during acute insulin-induced hypoglycaemia. PHYSIOL BEHAV. 67(1) 35–39, 1999.—This study sought to examine the effects of insulin-induced hypoglycaemia on anger state, and to describe the associations between change in the anger state and measures of anger trait and anger expression (assessed using the State-Trait Anger Expression Inventory). A hyperinsulinaemic glucose clamp was used to achieve controlled euglycaemia (5.0 mmol/L) and hypoglycaemia (2.6 mmol/L) in 18 nondiabetic subjects and 30 people with insulin-dependent diabetes mellitus (IDDM). Subjects underwent both hypoglycaemic and euglycaemic conditions, separated by 2 weeks, in a counterbalanced order. During each study condition subjects were asked to complete a questionnaire on anger state. Results at euglycaemia and hypoglycaemia were compared, and differences between the conditions were correlated with measures of anger trait and anger expression. Hypoglycaemia caused both nondiabetic and IDDM subjects to report a significant increase in feelings of anger, despite being in a nonconfrontational setting. However, there were no clear associations between an individual's change in reported anger and measures of anger trait and anger expression. No association was found between the change in anger state and the intensity of an individual's symptomatic response to hypoglycaemia.

γδ T-cells alterations in the peripheral blood of high risk diabetes type 1 subjects with subclinical pancreatic B-cells impairment

There is increasing evidence that CD3+ cells bearing γδ T-cell receptor (represent the minor subpopulation of the T-cells in the peripheral blood in humans) are involved in autoimmunity development. γδ T-cell receptor (TCR)+/CD8+ T-cells have been recently found to play a critical role in the pathogenesis and prevention of autoimmune diabetes in the animal model. The aim of the present study was the estimation the γδ T-cell subpopulation levels in the peripheral blood of subjects with preclinical and overt type 1 diabetes and their possible associations with the humoral immunity, metabolic parameters and pancreatic B-cells function. The study was carried out in three groups of subjects: 26 first degree relatives of type 1 diabetes patients (prediabetics) with the combinations of autoantibodies against pancreatic B-cells (ICA, GADA, IA-2A, IAA), 22 patients with a recent onset of type 1 diabetes and age and sex-matched 24 healthy volunteers (control group). A decrease was observed in the absolute numbers and percentages of γδ+/CD8+ and γδ+/CD8− T-cell subpopulations in peripheral blood in the prediabetics with the impaired first phase of insulin secretion in comparison to relatives with autoantibodies but still with normal B-cells function, patients with clinical diabetes and healthy controls. In conclusion, the study suggests that the γδ T-cells play an important role in the development of insulin-dependent diabetes mellitus (IDDM). It is possible that their levels in the peripheral blood could be an additional marker of preclinical detection of the disease, but further prospective studies in high risk of IDDM subjects are needed.

Systemic arterial compliance is reduced in young patients with IDDM.

Arterial elastic properties are altered with increasing age and in various disease states, including non-insulin-dependent diabetes mellitus (NIDDM). Whether young patients with insulin-dependent diabetes mellitus (IDDM) have reduced arterial compliance before developing endothelial dysfunction or overt micro- and macrovascular disease is unclear. Systemic arterial compliance and endothelium-dependent, flow-mediated vasodilation (FMD) was assessed in 25 individuals with uncomplicated IDDM (23 +/- 4 yr, 14 females and 11 males) and compared with 30 age-matched controls (15 females and 15 males). Arterial compliance was determined via simultaneous measurements of aortic blood flow and carotid arterial pressure. The relationship between arterial compliance and endothelial function (assessed by brachial artery FMD) was also examined. Arterial compliance was 29% lower in IDDM subjects compared with control subjects (0.46 +/- 0.05 vs. 0.65 +/- 0.07 arbitrary compliance units, P < 0.05). Blood pressure, lipid levels, and daily energy expenditure (a measure of physical activity levels) were not different between groups. Compliance in the IDDM group was not related to the integrity of endothelial vasodilator function, disease duration, or degree of glycemic control. Arterial compliance is reduced in young patients with IDDM before the development of overt micro- or macrovascular disease. Early assessment of arterial compliance may be useful in predicting the development of diabetic vascular complications.

Antibodies to oxidized LDL and LDL-containing immune complexes as risk factors for coronary artery disease in diabetes mellitus.

Several groups have published results from clinical studies supporting the involvement of anti-modified LDL antibodies as risk factors for the initiation or progression of cardiovascular disease. However, the data published so far are judged inconclusive because of several contradictory observations concerning the correlation between clinical evidence of arteriosclerosis and the levels of antibodies to oxidized LDL (oxLDL Ab). We have previously reported that oxLDL Ab exist both in free form and as antigen-antibody complexes (LDL-IC) in patients with insulin-dependent diabetes mellitus (IDDM). The presence of LDL-IC in IDDM patients has important implications: it may interfere with the assay of oxLDL antibodies and the levels of LDL-IC may correlate better with the development of arteriosclerosis than the levels of free oxLDL antibodies. To clarify these questions baseline samples collected from 49 IDDM patients, who subsequently developed coronary artery disease (CAD) during an 8-year follow-up period, were compared to baseline samples from 49 age-, sex-, and duration-matched control IDDM subjects who remained free of clinical CAD during an identical follow-up period. The levels of free oxLDL antibody were significantly lower in the patients who developed CAD. The same patients had significantly higher concentrations of total cholesterol, apolipoprotein B, and IgA in immune complex-enriched polyethylene glycol (PEG) precipitates. The concentration of IgG was also higher in PEG precipitates from patients who developed CAD, but did not reach statistical significance. This indicates that patients who develop CAD had higher levels of circulating LDL-IC, a fact that could not be deduced from the measurement of free oxLDL antibody concentrations. A linear regression analysis of the correlation between the concentrations of total cholesterol in PEG precipitates, taken as a surrogate measurement of PEG-precipitated oxLDL-IC, and the concentration of free oxLDL antibody in serum showed a statistically significant negative correlation (r = -0.229, P = 0. 024). Our results support the conclusion that oxLDL-IC may be a risk factor for the development of macrovascular disease in IDDM patients. We also have demonstrated that circulating oxLDL-IC interfere with the assay of free oxLDL antibodies.

T-cell response to proinsulin and insulin in type 1 and pretype 1 diabetes.

Insulin-dependent diabetes mellitus (IDDM) results from the selective destruction of pancreatic beta cells by a T cell-mediated autoimmune process. Insulin and proinsulin are the only known beta cell-specific autoantigens. Using short-term cultures of freshly isolated peripheral blood mononuclear cells, we evaluated T-cell responses to proinsulin and to insulin in IDDM patients and individuals at risk for IDDM. A proliferative T-cell response to proinsulin was observed in only 2 of 26 recent-onset IDDM subjects and 2 of 12 long-standing IDDM subjects and was associated with a proliferative response to insulin. In contrast, 5 of 13 islet cell autoantibody-positive first-degree relatives of IDDM patients showed a proliferative response to proinsulin alone, 3 of 13 to insulin alone, and 1 of 13 to both insulin and proinsulin. Overall, 9 of 13 ICA-positive first-degree relatives responded to either proinsulin or insulin. We observed an inverse relationship between antiinsulin antibodies and T-cell responses to insulin in ICA-positive first-degree relatives but not in long-standing IDDM patients. Our data indicate that proinsulin is a major antigen in IDDM and, further, illustrate the difference between the autoimmune response to insulin and the immune response to exogenous insulin.