Onset Of Overt Diabetes Research Articles

6674 Non-Progressive Diabetes Leading to Neurologic Diagnosis

Abstract Disclosure: F.L. Thelmo: None. M. Murugesh: None. B. Simon: None. Introduction: The autoantibody GAD (anti-glutamic acid decarboxylase) is highly associated with Type 1 diabetes (T1DM) and Latent Autoimmune Diabetes in Adulthood (LADA). If GAD is detected before the onset of overt diabetes, typically 80% of patients with abnormal glucose tolerance progress to insulin deficiency and the need for insulin treatment after 5 years.[1] Stiff Person Syndrome (SPS) is also associated with GAD antibodies, but in SPS, the GAD antibodies are believed to be different epitopes that target GABA production in neuromuscular pathways. We present a case of presumed LADA that did not progress for 30 years, with progressive neurologic symptoms leading to a diagnosis of SPS in later adulthood.Case: A 52-year-old female presented for evaluation of T1DM and worsening neuropathies. She had a long history of prediabetes, with mildly elevated glucose values noted on labs since her early twenties. There was no family history of T1DM or autoimmune conditions. Six years ago, she sought endocrine evaluation. HgbA1c values were 6.1 to 6.6%. Intermittent use of continuous glucose monitoring (CGM) revealed post-prandial hyperglycemia up to 180mg/dL, occasionally (but rarely) exceeding 200mg/dL. She recalls being told that she had positive antibodies (unclear which ones tested) and given a diagnosis of T1DM. She declined insulin and maintained glycemic control with carbohydrate restriction and exercise; there were no episodes of diabetic ketoacidosis. She then developed neurologic symptoms: fullness, tightness and bloating in the abdomen (diagnosed with gastroparesis on scanning) and after a COVID 19 booster in 2021, muscle spasms in the legs and back with worsening abdominal tightness. At the time of her current presentation, A1C was 6.4%, glycated albumin was 14.4% (prediabetes range 13.6 - 15.5%) and CGM time in range was 99%. A non-fasting C-peptide was 3.6 ng/mL (1.1- 4.4ng/mL) with glucose of 119 mg/dL. Repeat antibody testing revealed undetectable IA-2 and ZnT8 antibodies, but GAD was grossly elevated at 1,015.3 U/mL. Given the unusually high GAD titer, SPS was suspected, and this diagnosis was confirmed on referral to neurology. The patient was advised to liberalize diet and will be monitored with HgbA1c and serial C-peptide levels to assess progression in the future. Discussion: While high GAD antibody levels are associated with progression to insulin dependence in adults with LADA, in SPS the GAD titers tend to be even higher2. The presence of only one auto-antibody for T1DM (and not multiple), long-standing non-progressive hyperglycemia, and normal C-peptide pointed away from autoimmune diabetes being the etiology for mild glucose intolerance in this patient. If neurologic symptoms are present, high GAD should prompt the evaluation for other syndromes associated with GAD antibody epitopes such as SPS. Presentation: 6/2/2024

HbA1c or fructosamine on evaluating glucose intolerance in children with beta- thalassemia

BackgroundBeta-thalassemia major (β-TM) patients are more likely to experience blood glucose intolerance and to date; the blood markers that could evaluate this are debatable. So, this study aimed to assess the roles of glycated hemoglobin A1c (HbA1c) and fructosamine in evaluating glucose intolerance in children with β-TM and figuring out role of insulin resistance in these patients.MethodsOne hundred children diagnosed with β-TM and 100 age and sex-matched controls were enrolled. Fasting plasma glucose (FPG), 2-h post-prandial blood glucose (2-h PG), HbA1c, fructosamine, fasting insulin level (FINS), insulin resistance index (HOMA-IR), and insulin sensitivity index (HOMA-IS) were evaluated.ResultsFPG and 2-h PG revealed glucose intolerance in 51 patients (51%), 19 of them had diabetes mellitus. HbA1c, fructosamine, FINS, and HOMA-IR showed a high statistically significant increase in patients compared to controls, (P < 0.001). Results revealed fructosamine was more specific in detecting prediabetes state and more sensitive in identifying diabetes mellitus in our patients when compared to HbA1c.ConclusionsDespite controversies on HbA1c in children with β-TM, it is still valuable in glucose intolerance detection. Fructosamine showed more sensitivity and specificity. Furthermore, insulin resistance was prevalent in children with β-TM highlighting the necessity of regular glycemic state evaluation.ImpactGlucose intolerance is a common complication in beta thalassemia patients.Conflicting data was reported about the role of HbA1c and fructosamine in evaluating glucose intolerance in thalassemic patients.Fructosamine does not yet have a threshold that may be used to distinguish between patients who have diabetes mellitus and those who do not.Fructosamine was more specific in detecting blood glucose intolerance compared to HbA1c and was more sensitive for diagnosing diabetes mellitus.Insulin resistance was common in patients with beta-thalassemia and often present before the onset of overt diabetes.

Serum Levels of Activin A: Predictor of Insulin Resistance and Atherosclerosis in Prediabetics.

Pathological effects of dysglycemia and insulin resistance on atherosclerosis and cardiac remodeling starts as early as in the prediabetic state before the onset of overt diabetes. Activin A is a molecule with multiple functions, including an important part in glucose homeostatic mechanisms as well as inflammatory processes and is therefore being researched as a useful novel biomarker for prompt recognition of the risk of cardiovascular disease (CVD) in prediabetic individuals, thereby helping in disease prognostication and early institution of therapeutic measuresObjective: The study aimed to measure serum levels of activin A in prediabetic patients and evaluate them in comparison to normoglycemic controls. The association of activin A with carotid intima media thickness (CIMT), left ventricular diastolic dysfunction (LVDD), and homeostatic assessment of insulin resistance (HOMA-IR) was also studiedMaterials and methods: A total of 60 prediabetic cases and 60 normoglycemic control subjects [matched as per age, gender, and body mass index (BMI)] were recruited. Measurement of serum glucose levels (fasting and postprandial) and fasting insulin levels and glycated hemoglobin (HbA1c) levels were done in all the subjects. The values of HOMA-IR were computed using established formulae. Enzyme-linked immunosorbent assay (ELISA) kits were used for the evaluation of serum levels of activin A in both groups. Parameters for the two groups were compared. In the cases, CIMT (using B-mode ultrasound) and LVDD (using two-dimensional (2D) echocardiography) were measured and correlated with activin A levelsResults: Serum fasting insulin (mIU/L) was considerably higher in cases than in the controls (p &lt; 0.001). HOMA-IR median [interquartile range (IQR)] was 4 (3.25-4.93) in some cases, and that in the control group was 1.2 (0.88-1.5) (p &lt; 0.001). Serum activin A levels in the cases group had a median (IQR) of 263.55 (227.1-279.5) ng/mL, which was substantially greater as compared to the control group 159.9 (150.7-178.7) ng/mL (p &lt; 0.001). A significant positive association of serum activin A levels with HOMA-IR (ρ = 0.75, p &lt; 0.001) and CIMT (ρ = 0.50, p &lt; 0.001) was found. In LVDD grade I and II groups, the serum levels of activin A were 257.86 (219.3-271.2) ng/mL and 269 (244.19-291.5) ng/mL, respectively (p = 0.12)Conclusion: A substantial proportion of morbidity and mortality related to dysglycemic states can be attributed to cardiovascular complications. Elevated levels of activin A in prediabetes can act as an indicator of subclinical CVD leading to early diagnosis and intervention.

Hyperferritinemia: An Early Predictor of Insulin Resistance and Other Complications of Type 2 Diabetes Mellitus

Background: The incidence of type 2 diabetes mellitus is growing globally and has become a significant health burden accounting for 90% of total cases of diabetes. The present study was carried out to determine the interaction of insulin resistance and anemia in type 2 diabetes (T2D) patients. Material &amp; Methods: Atotal of 110 type 2 diabetic patients were examined, and the laboratory investigations were carried out, including the lipid, anemia, and diabetic profile, along with the calculation of the Homeostatic Model Assessment for Insulin Resistance. Results: Serum ferritin and iron levels showed a significant positive association with Body Mass Index, fasting glucose, postprandial glucose, glycated hemoglobin (HbA1C), serum insulin levels,Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), serum cholesterol, serum triglycerides and urinary protein/creatinine ratio. However, creatinine was positively associated with ferritin only. The significantly increased BMI, fasting &amp; post-prandial blood glucose, HbA1c, serum ferritin, serum iron, total cholesterol, triglycerides, serum insulin, and urine protein/creatinine ratio were observed in patients with the HOMA-IR values of &gt;3 than the patients with HOMA-IR values of ≤3. Conclusion: Increased serum ferritin levels reflect its role in insulin resistance, poor glycemic control, obesity, dyslipidemia, and complications of T2DM like diabetic nephropathy, diabetic neuropathy, and diabetic retinopathy. Therefore, hyperferritinemia can be used as an early tool to diagnose insulin resistance before the onset of overt diabetes.

Increased risk for microvascular complications among women with gestational diabetes in the third trimester

AimsThe risk of microvascular disease has been thought to commence with the onset of overt diabetes. Women with gestational diabetes have only had a short-term exposure to frank hyperglycemia, but, due to underlying β-cell dysfunction, they may also have had long-term exposure to mild degrees of hyperglycemia. The aim of the study was to determine whether women with gestational diabetes are at increased risk for microalbuminuria and retinopathy compared to women with normal glucose tolerance in pregnancy. MethodsWe recruited women aged ≥ 25 years with singleton pregnancies at 32 to 40 weeks’ gestational age, with and without gestational diabetes. Women with hypertension, preeclampsia, or pre-gestational diabetes were excluded. ResultsOf 372 women included in the study, 195 had gestational diabetes. The prevalence of microalbuminuria was 15% among those with gestational diabetes versus 6% in those with normal glucose tolerance (adjusted odds ratio 2.4, 95% confidence interval 1.1 to 5.2, p = 0.006). Diastolic blood pressure and HbA1c were associated with microalbuminuria. The prevalence of retinopathy did not differ between groups (10% versus 11%). ConclusionsWomen with gestational diabetes have an increased risk of microalbuminuria in the third trimester, despite having been exposed to only a brief period of overt hyperglycemia.

209Glucose is associated with future atrial fibrillation and heart failure already at prediabetes levels, a 19 year follow up of 243,665 subjects

Abstract Background Dysglycaemia is associated with cardiovascular disease even below the diagnostic diabetes threshold. Atrial fibrillation (AF) has been found to be associated with the metabolic syndrome and life-style changes after AF have been found to reduce recurrence of AF. Purpose We explored the association glucose and risk of first event of AF, HF and combined event. Methods Subject with fasting glucose in the AMORIS cohort, obtained 1985–1996 at routine occupational health check-ups or primary care in the Stockholm area were included. Subjects with prevalent AF, HF, ischemic heart disease, revascularization and cerebrovascular disease were excluded. Glucose levels were categorised as low (&lt;3.9 mmol/L), normal (3.9–6.0mmol/L), impaired (IFG; 6.1–6.9 mmol/L) and diabetes (≥7.0 mmol/L or a diabetes diagnosis) according to WHO definition in 2006. First events of AF, HF or a combined event was identified until December 2011 by linkage to national registries. Information on co-morbidities was obtained from the National Patient Register. Hazard ratios (HR and 95% CI) by glucose group for AF and heart failure were calculated using Cox proportional hazards with attained age as timescale and adjusting for gender, total cholesterol and triglycerides. The change in AF risk by increasing glucose level was described by using splines (Figure). Results 243 665 subjects with mean age 48.3 at index date, 54% male were included. During a mean follow-up time of 19.1 years and 4,7 million person years, 23 522 events of AF, 21 411 events of HF and 35 131 combined events occurred. The proportion with IFG and diabetes were 3.2% and 3.3% respectively. In the diabetes group about half were diagnosed prevalent cases (1.5%). Glucose was continuously associated with developement of AF (Table and Figure) and even more of HF (Table). Events (n) and HR by glucose category Atrial fibrillation Heart failure Combined event Event HR [95% CI] Event HR [95% CI] Event HR [95% CI] Low 405 0.97 [0.88–1.08] 326 0.97 [0.87–1.08] 598 1.00 [0.92–1.09] Normal 20 663 1.00 17 811 1.00 30 159 1.00 IFG 1185 1.20 [1.13–1.28] 1319 1.43 [1.35–1.51] 1901 1.30 [1.24–1.36] Diabetes 1269 1.28 [1.20–1.35] 1955 2.19 [2.08–2.29] 2473 1.73 [1.66–1.81] Events (n) of AF, HF and combined and HR (95% CI) by fasting glucose category. HR for AF by glucose level spline graph Conclusion Dysglycaemia, including glucose levels below the diabetes threshold, is continuously associated with future risk of both AF and HF. These data are important considering the large population with undetected dysglycaemia at risk for AF and HF where preventive measures including life-style changes could be of importance even before the onset of overt diabetes. Acknowledgement/Funding Swedish Heart and Lung foundation

Association of glucose homeostasis measures with heart rate variability among Hispanic/Latino adults without diabetes: the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

BackgroundReduced heart rate variability (HRV), a measure of cardiac autonomic function, is associated with an increased risk of cardiovascular disease (CVD) and mortality. Glucose homeostasis measures are associated with reduced cardiac autonomic function among those with diabetes, but inconsistent associations have been reported among those without diabetes. This study aimed to examine the association of glucose homeostasis measures with cardiac autonomic function among diverse Hispanic/Latino adults without diabetes.MethodsThe Hispanic community Health Study/Study of Latinos (HCHS/SOL; 2008–2011) used two-stage area probability sampling of households to enroll 16,415 self-identified Hispanics/Latinos aged 18–74 years from four USA communities. Resting, standard 12-lead electrocardiogram recordings were used to estimate the following ultrashort-term measures of HRV: RR interval (RR), standard deviation of all normal to normal RR (SDNN) and root mean square of successive differences in RR intervals (RMSSD). Multivariable regression analysis was used to estimate associations between glucose homeostasis measures with HRV using data from 11,994 adults without diabetes (mean age 39 years; 52 % women).ResultsHigher fasting glucose was associated with lower RR, SDNN, and RMSSD. Fasting insulin and the homeostasis model assessment of insulin resistance was negatively associated with RR, SDNN, and RMSSD, and the association was stronger among men compared with women. RMSSD was, on average, 26 % lower in men with higher fasting insulin and 29 % lower in men with lower insulin resistance; for women, the corresponding estimates were smaller at 4 and 9 %, respectively. Higher glycated hemoglobin was associated with lower RR, SDNN, and RMSSD in those with abdominal adiposity, defined by sex-specific cut-points for waist circumference, after adjusting for demographics and medication use. There were no associations between glycated hemoglobin and HRV measures among those without abdominal adiposity.ConclusionsImpairment in glucose homeostasis was associated with lower HRV in Hispanic/Latino adults without diabetes, most prominently in men and individuals with abdominal adiposity. These results suggest that reduced cardiac autonomic function is associated with metabolic impairments before onset of overt diabetes in certain subgroups, offering clues for the pathophysiologic processes involved as well as opportunity for identification of those at high risk before autonomic control is manifestly impaired.

Genome-Wide DNA Methylation in Mixed Ancestry Individuals with Diabetes and Prediabetes from South Africa.

Aims. To conduct a genome-wide DNA methylation in individuals with type 2 diabetes, individuals with prediabetes, and control mixed ancestry individuals from South Africa. Methods. We used peripheral blood to perform genome-wide DNA methylation analysis in 3 individuals with screen detected diabetes, 3 individuals with prediabetes, and 3 individuals with normoglycaemia from the Bellville South Community, Cape Town, South Africa, who were age-, gender-, body mass index-, and duration of residency-matched. Methylated DNA immunoprecipitation (MeDIP) was performed by Arraystar Inc. (Rockville, MD, USA). Results. Hypermethylated DMRs were 1160 (81.97%) and 124 (43.20%), respectively, in individuals with diabetes and prediabetes when both were compared to subjects with normoglycaemia. Our data shows that genes related to the immune system, signal transduction, glucose transport, and pancreas development have altered DNA methylation in subjects with prediabetes and diabetes. Pathway analysis based on the functional analysis mapping of genes to KEGG pathways suggested that the linoleic acid metabolism and arachidonic acid metabolism pathways are hypomethylated in prediabetes and diabetes. Conclusions. Our study suggests that epigenetic changes are likely to be an early process that occurs before the onset of overt diabetes. Detailed analysis of DMRs that shows gradual methylation differences from control versus prediabetes to prediabetes versus diabetes in a larger sample size is required to confirm these findings.

Pre-CKD- Do we Need Another Hero?

Screening is the systematic use of a test for a health problem or risk factor when no recognized signs or symptoms would indicate the presence of that problem or risk factor. Abnormal glucose metabolism can be documented years before the onset of overt diabetes. Nowadays, prediabetes can be subdivided into impaired fasting glucose or impaired glucose tolerance. Substantial number of subjects with either will progress to overt diabetes within years. Prediabetes bears also the increased risk of cardiovascular complications. Prehypertension is much newer term introduced by the seventh report of the Joint National Committee (JNC 7) published in 2003 as systolic blood pressure from 120 to 139 mmHg or diastolic blood pressure from 80 to 89 mmHg in adults (not receiving blood pressure-lowering treatment). Similarly prehypertension also increased the risk of cardiovascular complications and progression to hypertension. Chronic kidney disease is also highly prevalent mainly in the elderly. It is associated with important adverse outcomes such as cardiovascular mortality and morbidity. Factors associated with higher risk of chronic kidney disease include mainly hypertension, diabetes, obesity and older age. Early detection and diagnosis of chronic kidney disease may prevent the full blown disease and its end-stage requiring renal replacement therapy. The review focus on the problem of high risk population for development of diabetes, hypertension and whether time has come to focus also on the conditions predisposing to the development of chronic kidney disease.

Immunoregulatory Effect of Anti-thymocyte Globulin Monotherapy on Peripheral Lymphoid Tissues of Non-obese Diabetic Mice

Objective Experimental and clinical studies have shown that autoimmunity-causing diabetes may be abrogated by immune intervention. Several anti–T-lymphocyte antibodies focus on distinct T-cell targets. We tested the effect of murine anti-thymocyte globulin (ATG; Genzyme, Framingham, MA) in peripheral lymphoid organs of non-obese diabetic (NOD) mice after the onset of hyperglycemia. Methods Diabetic NOD mice were treated with two doses of ATG (1 mg totally) or maintained without treatment as controls. Blood glucose levels were monitored twice a week. The mice were terminated at day 0, 7, 14, or 28 after the initiation of the study. Subpopulations of T-lymphocytes and FoxP3+ (forkhead box P3 positive) regulatory T-cells were analyzed among elements isolated from the spleen and pancreatic lymph nodes. Results Mice with blood glucose levels greater than 13 mmol/L were included in the study. Diabetes remission occurred in 16% (3/19) of mice treated with ATG. Only one case of remission was observed in the control group (6%; 1/16). ATG therapy a significantly decreased the CD8+/CD4+ T-lymphocyte ratio. Among splenocytes, a significant difference was detected only on day 7 (0.069 versus 0.198 T-lymphocyte ratio); in lymph nodes, a decrease was observed on day 28 (0.21 versus 0.51 T-lymphocytes ratio). The regulatory T-cells population increased after ATG administration compared with the control group at day 7 (16.2% versus 10.8% in CD4+ splenocytes; 20.7% versus 10.3% in CD4+ lymph node cells). However, the increased FoxP3+ cell population was not durable. Conclusions ATG treatment of diabetic NOD mice showed an immunoregulatory effect in peripheral lymphoid tissue with a significantly deceased CD8+/CD4+ ratio, which, however, did not normalize the metabolic parameters in a short period after the onset of overt diabetes.

Diet with a low n‐6/n‐3 essential fatty acid ratio when started immediately after the onset of overt diabetes prolongs survival of type 1 diabetes model NOD mice

Type 1 diabetes is a multifactorial disease involving genetic and environmental factors and results from the destruction of pancreatic islet β cells, virtually the only source of insulin. When the majority of β cells are lost, a 'honeymoon' period of variable length follows: namely, a fleeting phase of residual endogenous insulin production, during which glycemic control is achieved with modest or no doses of insulin. However, the remaining β cells are eventually lost, causing the individual to become insulin-dependent and to require long-term insulin therapy or islet transplantation. Here we show that NOD mice, a type 1 diabetes model, survived significantly longer when their diet was changed from one chow with a high essential fatty acid (EFA) ratio (n-6/n-3, 14.5) to another with a low n-6/n-3 ratio (3.0) within 6 days after the onset of overt diabetes (i.e. the 'honeymoon' period), than mice that were continuously fed with the chow with the high n-6/n-3 ratio. This effect was not observed when the chow was changed later than 9 days after the onset. Significantly larger number of islets remained with suggestive islet neogenesis from the pancreatic duct and pathological changes in renal glomeruli were significantly milder in NOD mice fed the chow with the low n-6/n-3 ratio within 6 days after the onset of overt diabetes than those continuously fed with the high-n-6/n-3-ratio chow. These findings indicate that a diet with a low n-6/n-3 ratio prolongs the 'honeymoon' period by retaining the β cell mass, suggesting its potential therapeutic merit.

Genetic and biochemical pathways of β‐cell failure in type 2 diabetes

We review mechanisms of beta-cell failure in type 2 diabetes. A wealth of information indicates that it is caused by impaired insulin secretion and decreased beta-cell mass. Interestingly, there appears to be a link between these two mechanisms. The earliest reaction to peripheral insulin resistance is an increase in insulin production, owing primarily to increased secretion, and to a lesser extent to decreased clearance. Experimental animal models indicate that hyperinsulinaemia promotes an increase in beta-cell mass, largely via increased beta-cell replication. In contrast, following the onset of overt diabetes, there is a slowly progressive loss of beta-cell function and mass, both in animal models and in diabetic humans. It is of great interest that most diabetes-associated genes identified in genome-wide association studies appear to be enriched in the beta-cell and to have the potential to regulate mass and/or function. Here, we review evidence derived from experimental animal models to unravel the mechanisms underlying beta-cell dysfunction. We focus primarily on signalling pathways, as opposed to nutrient sensing, and specifically on the notion that insulin and growth factor signalling via Foxo1 in pancreatic beta-cells links insulin secretion with cellular proliferation and survival.

Serum resistin level is associated with insulin sensitivity in Japanese patients with type 2 diabetes mellitus

Impaired insulin secretion and decreased insulin sensitivity are the main pathophysiologic features responsible for development of hyperglycemia in type 2 diabetes mellitus. Insulin resistance is often associated with increased adipose tissue mass. To examine which variables influence insulin sensitivity, we compared metabolic parameters, serum resistin, leptin, and adiponectin concentrations to the insulin sensitivity, obtained by frequently sampled intravenous glucose tolerance test using the minimal model analysis, in 113 Japanese patients with type 2 diabetes mellitus. Duration of diabetes, fasting plasma glucose, fasting insulin, homeostasis model assessment of insulin resistance index, and serum resistin concentration were significantly higher in the insulin-resistant subgroup compared with the insulin-sensitive subgroup and correlated with insulin sensitivity. Stepwise regression analysis also identified these parameters as independent regulators of insulin sensitivity. The present study reconfirmed that fasting insulin level or homeostasis model assessment of insulin resistance would be a surrogate measure of insulin resistance and demonstrated that insulin resistance increases progressively after the onset of overt diabetes and that the serum resistin level is associated with insulin sensitivity, suggesting that resistin plays an important role in the development of insulin resistance in Japanese patients with type 2 diabetes mellitus.

Significance of serum CXCL10/IP-10 level in type 1 diabetes

Although we have previously reported an elevated serum level of CXCL10/IP-10 (CXCL10), a Th1 chemokine, in type 1 diabetic patients, little is known about the origin of serum CXCL10 and its significance in type 1 diabetes. Therefore, we examined serum CXCL10 level in NOD mice in association with the expression level of CXCL10 in the pancreas, pancreatic lymph nodes (LN) and spleen. Serum CXCL10 level increased over time towards the onset of diabetes, and was significantly higher in the “diabetic” period (20 and 24 weeks of age and at onset of diabetes) than in the “pre-diabetic” period (4, 8 and 16 weeks of age). Moreover, serum CXCL10 level was associated with CXCL10 and CXCR3 mRNA level in pancreatic LN. Furthermore, it seemed that serum CXCL10 level increased just before (or at) the onset of overt diabetes. These results suggest that serum CXCL10 level may reflect accumulation of Th1 lymphocytes in pancreatic LN, and measurement of serum CXCL10 level may be useful to assess the pathophysiology of the disease course in type 1 diabetes.

The interplay of cardiovascular risk factors in the metabolic syndrome and type 2 diabetes

Cardiovascular disease (CVD) is the major cause of morbidity and mortality in the western world, and patients with diabetes have a 2- to 3-fold greater risk of CVD death than those without. This suggests an interaction between diabetes and other CVD risk factors such as hypertension and dyslipidaemia. The treatment of CVD risk factors in patients with diabetes reduces the incidence of CVD death but macrovascular damage is present in patients prior to the onset of overt diabetes, so the early identification and treatment of patients at risk of diabetes is essential for the primary prevention of CVD. Risk factors for diabetes and CVD are more likely to occur simultaneously than would be expected by chance, and this cluster of disorders is collectively called the metabolic syndrome. Individuals with the metabolic syndrome have an increased risk of CVD prior to the development of impaired glucose tolerance and diabetes, and patients with both the metabolic syndrome and diabetes are at greater risk of coronary heart disease death than patients with either diabetes or the metabolic syndrome alone. Although reducing glucose levels significantly reduces the risk of microvascular disease in patients with diabetes and/or the metabolic syndrome, it is not sufficient to significantly reduce the incidence of macrovascular disease. Additional risk factors, including hypertension and dyslipidaemia, must also be targeted in patients with these disorders.

Identification of pancreatic exocrinopathy in non-obese diabetic mice by gene subtraction analysis.

Type 1 diabetes is an immune-mediated disease with pancreatic infiltration and subsequent beta cell destruction. In this study pancreatic exocrinopathy in non-obese diabetic mice (NOD) was identified using gene subtraction methods (SSH) and macroarray analysis. Female NOD mice were treated with cyclophosphamide for acceleration and synchronization of the disease process at 70 d of age and analysed 10 d later, before the onset of overt diabetes. Extraction of total RNA of pancreas was followed by subtraction using the SSH technique. Pools of cDNA were generated using total RNA from treated and untreated NOD mice. Subtraction of cDNA pools of cyclophosphamide treated mice from cDNA pools of untreated mice resulted in a cDNA library, from which 480 clones were randomly selected. The clones were hybridized against labelled cDNA-probes generated from cyclophosphamide-treated and control NOD mice. Fifty-three clones (11 %) revealed at least twofold differential gene expression after cyclophosphamide treatment. Three of the downregulated genes (amylase, carboxypeptidase and preprotrypsin) were selected for evaluation of macroarray data by quantitative real-time PCR. Analysis of real-time PCR data confirmed suppression of gene expression with highest fold change for amylase (4.68-fold) followed by carboxypeptidase (2.79-fold) and preprotrypsin (2.14-fold). These results lead to the conclusion that inflammation in this animal model of type 1 diabetes is not restricted to pancreatic islets and that subtraction followed by macroarray analysis is capable of identifying genes responsible associated with disease progression.

Genetic susceptibility in type 1 diabetes and its associated autoimmune disorders.

Animal models of type 1 diabetes There are several animal models of type 1A diabetes (immune mediated). The first inbred animal model evolved from the discovery of diabetic animals in an outbred colony of Wistar rats maintained at the Bio Breeding Research Laboratories in Ottawa, Canada. The Bio Breeding (BB) rat develops spontaneous immune-mediated diabetes with at least four loci contributing to disease: the major histocompatibility complex (MHC, iddm2) on rat chromosome 20; the lymphopenic locus iddm1 on rat chromosome 4 [1], iddm3 on rat chromosome 2 [2], and a fourth locus on rat chromosome 15. The lymphopenic phenotype (iddm1 or lyp) locus has been mapped to a syntenic region of rat chromosome 4 [1,3]. Mutation at this locus in a homozygous state produces a severe T cell lymphopenia. Hornum and co-workers have mapped the gene to a 0.3-cM region between markers D4Got59 and Abp1 and constructed a 550-kb P1-derived artificial chromosome (PAC) contig covering the region [4]. They found a frameshift mutation in Immune-Associated Nucleotide4 (Ian4) gene which encodes a GTP-binding protein localized in the outer mitochondrial membrane [5]. This mutation results in a truncated gene product that lacks twothirds of the total protein. They hypothesized that Ian 4 is involved in the regulation of T-cell apoptosis, making it an excellent candidate for iddm1. The Ian4 gene product is anchored to the outer mitochondrial membrane, and this organelle is an important site for the regulation of cell death [6]. The same mutation was found by MacMurray and co-workers but they termed the gene Ian5 [7]. Some Ian genes are expressed in mature T cells and switched on during thymic T-cell development [8–10]. The Komeda diabetes-prone (KDP) rat [11], a diabetesprone substrain of the Long-Evans Tokushima lean (LETL) rat is characterized by autoimmune destruction of pancreatic β cells [12], rapid onset of overt diabetes with no sex difference, and no significant T cell lymphopenia. The gene Cblb (Casitus B-lineage lymphoma b, also known as Cas-Br-M murine ectropic retroviral transforming sequence b) was a potential candidate given its influence on immune function. Yokoi et al. [13] confirmed a C → T homozygous nonsense mutation (arginine to a stop at codon 455, Arg455X) that removes 484 amino acids, including the proline-rich region and leucine zipper domain. The mutation is specific to the KDP rat and its original LETL strain. Approximately 80% of the Iddm/kdp1 homozygous mutant animals develop diabetes with severe insulitis, and most of the remainder showed mild to moderate insulitis. Neither heterozygous nor wildtype animals developed diabetes. They demonstrated that Cblb is a important regulator of autoimmunity and Cblb is a major susceptibility gene for rat type 1 diabetes [14]. The non-obese diabetic mouse is the best studied spontaneous animal model of type 1 diabetes. Diabetes susceptibility in the NOD is polygenic, with a major influence of genes within the MHC. Linkage analyses have identified at least 19 susceptibility loci (Idd1-Idd19) that contribute to disease pathogenesis [15,16]. Lymphocytes mediate the specific destruction of insulin-producing β cells. These loci can either confer susceptibility or resistance to expression of insulin autoantibodies, insulitis and or disease development. Idd1 has been mapped to the MHC locus on mouse chromosome 17 [17,18]. Idd1 mapped to class II I-A and I-E regions as a gene complex [19], but the incidence of the disease is strongly affected by a gene or genes outside of this segment (Idd16). Variants of the beta-2 microglobulin gene is one of the first non-MHC genes to by clearly identified. Though neither the insulin 2 gene on chromosome 7 nor the insulin 1 gene on chromsome 19 show linkage to diabetes, in crosses with normal mouse strains, knockouts of either of these genes greatly influences the development of diabetes. Several new mouse models of human type 1 diabetes have been developed using transgenic mice. We found

Increased beta-cell proliferation and reduced mass before diabetes onset in the nonobese diabetic mouse.

To determine whether loss of beta-cell mass and function in the NOD mouse occurs gradually, beginning after the onset of insulitis, or abruptly, just before the onset of overt diabetes, beta-cell mass and rates of beta-cell proliferation and insulin secretory responses from the perfused pancreas were measured in NOD and control NOD/Scid mice at 8-9, 13, and 18 weeks of age. Of the NOD mice, 11 and 70% had diabetes (fasting blood glucose >8.3 mmol/l) at 13 and 18 weeks of age, respectively. Beta-cell mass in 8-week-old NOD mice was 69% of control mice (P>0.05), but the rate of 5-bromo-2-deoxyuridine uptake was greater, suggesting a compensatory proliferative response to ongoing autoimmune beta-cell destruction. Despite an increase in the rate of beta-cell proliferation, beta-cell mass was significantly reduced by 42% in 13-week-old nondiabetic NOD mice and by 73% in 18-week-old diabetic NOD mice. Insulin secretory responses to glucose and arginine demonstrated reductions of similar magnitude. In 18-week-old diabetic NOD mice, insulin secretion was reduced to a greater degree than beta-cell mass, suggesting the presence of beta-cell dysfunction in addition to reduced mass. These results suggest that in the NOD mouse, beta-cell destruction begins soon after the onset of insulitis. Despite a compensatory beta-cell proliferative response, beta-cell mass progressively falls and is significantly reduced by 13 weeks despite normal blood glucose concentrations. Diabetes may be present when residual beta-cell mass represents 30% of control levels.

Impaired glucose tolerance, type 2 diabetes, and carotid wall thickness: the Insulin Resistance Atherosclerosis Study.

To assess whether people with impaired glucose tolerance (IGT) exhibit an increased risk of atherosclerosis as measured by the thickness of the carotid artery. We examined the relationship between glucose tolerance status and subclinical atherosclerosis in the Insulin Resistance Atherosclerosis Study (IRAS). The IRAS is an epidemiological study of 1,625 Hispanic, African-American, and white men and women, with approximately equal numbers of subjects with normal glucose tolerance (NGT), IGT, and type 2 diabetes as assessed by an oral glucose tolerance test. Half of those with diabetes were previously unaware of their condition and were defined as having new diabetes. Persons using insulin were excluded. The intima-media thickness (IMT) of the common carotid artery (CCA) and internal carotid artery (ICA) was measured as an index of subclinical atherosclerosis using B-mode ultrasonography. Adjusted for demographics and smoking, CCA-IMT increased most notably at the level of established diabetes (802, 822, 831, and 896 microm for NGT, IGT, new diabetes, and established diabetes, respectively). Adjustment for coronary heart disease (CHD) risk factors, which tended to worsen across glucose tolerance category, further minimized the slightly graded relationship. The relationship with the ICA-IMT was steeper and again suggested that the increased wall thickness is associated with diabetes, not with IGT. The relationship between glucose tolerance category and IMT was similar in men and women. We observed considerably greater IMT among persons with established diabetes but no significant increase in persons with IGT. These data suggest that the increased risk of CHD observed in persons with diabetes may largely develop after the onset of overt diabetes.

Change of plasma 1,5-anhydro-D-glucitol levels after the onset of diabetes in spontaneous diabetes prone BB/Wor/(/)Tky rats.

Plasma 1,5-anhydro-D-glucitol (AG) is a marker of the diabetic state and also reflects the glycosuria induced by hyperglycemia but not by renal pathology. To investigate the benefits of the AG determination in order to diagnose diabetes in BB/Wor/(/)Tky rats, AG was measured in non-diabetic (n = 104) and diabetic (n = 113) BB/Wor/(/)Tky rats. AG was significantly higher in non-diabetic rats than in diabetic rats (25.2 +/- 9.3 vs 4.1 +/- 7.4 micrograms/ ml, mean +/- SD, p < 0.001). The best cut-off level for AG (8.5 micrograms/ml) was highly specific (100%) for ruling out diabetes and fairly sensitive (82.3%) to detect diabetes. Based on the AG cut-off levels, 90% of false-negative diabetic rats (18/20) were observed within 4 days after the onset of diabetes, which corresponded to 38.3% in diabetic rats (18/47) at that time. The false-negative diabetic rats and positive rats could be effectively distinguished based on the cumulative points given according to the urinary glucose after the onset of diabetes. 1 point for each cross [+] indicating glycosuria using the Testape, i.e. 2 or less points false negative and 4 or more points for diabetic rats in the first 4 days. In conclusion, there is a close inverse relation between the level of plasma AG and the amount of glycosuria detected just after the onset of overt diabetes in BB/Wor/(/)Tky rats.