Why does diabetes mellitus increase the risk of cardiovascular disease?

The main etiology for mortality and a great percentage of morbidity in patients with diabetes mellitus is atherosclerosis. The pathogenesis of cardiovascular disease (CVD) in diabetes is multifactorial and can be affected by metabolic and other factors. A hypothesis for the initial lesion of atherosclerosis is endothelial dysfunction, defined pragmatically as changes in the concentration of the chemical messengers produced by the endothelial cell and/or by blunting of the nitric oxide-dependent vasodilatory response to acetylcholine or hyperemia. Endothelial dysfunction has been documented in patients with diabetes and in individuals with insulin resistance or at high risk for developing type 2 diabetes. The way endothelial function altered in diabetic patients is not yet fully understood, but the loss of normal endothelial function could be involved in the pathogenesis of diabetic angiopathy, as endothelial dysfunction is associated with diabetic microangiopathy and macroangiopathy. Factors associated with endothelial dysfunction in diabetes include activation of protein kinase C, overexpression of growth factors and/or cytokines, and oxidative stress. Changes in endothelium function may lead to the coronary artery circulation being unable to cope with the increased metabolism of myocardial muscle independently of a reduced coronary artery diameter. Finally, recent reports indicate that an improved metabolic control in diabetic patients, whatever the treatment used, is associated with near normalization or restoration of normal endothelial function.     

Is diabetes a risk factor for central venous access port-related bloodstream infection in oncological patients?

It was a dogma that patients with diabetes mellitus (DM) are at increased risk of infection or death associated with an infection. However, in cancer patients, this has not been well investigated. The aim was to investigate whether diabetic patients with cancer are at high risk of central venous access port (CVAP)-related bloodstream infection (BSI), and to analyse mortality after CVAP-BSI. A total of 17 patients with type 1 DM (T1DM), 66 with type 2 DM (T2DM) and 307 non-diabetic patients were included. Each patient was followed up until the first late CVAP-BSI or for a maximum for 1 year in the absence of a CVAP-BSI. Fifty-three CVAP-BSIs occurred in 66,528 catheter-days. The cumulative incidence of CVAP-BSI was not higher in T1DM (5.9 %; p?=?0.17) and T2DM (19.7 %; p?=?0.70) compared with the non-diabetic patients (12.7 %). However, in patients with CVAP-BSI, the 1-month crude mortality rate was higher in DM patients (42.9 % vs. 15.4 %; p?=?0.04), whereas the mortality in patients without CVAP-BSI was similar in both groups of patients (19.8 % vs. 17.1 %; p?=?0.58). Of the 12 deaths that occurred within 1 month of CVAP-BSI, 16.66 % was attributable to CVAP-BSI. The predictive factor of 1-month mortality was DM (p?=?0.04). Parenteral nutrition (PN) was independently associated with CVAP-BSI in diabetic patients (p?=?0.001). In this study, diabetes did not increase the risk of CVAP-BSI, but mortality was higher in diabetic patients who had a CVAP-BSI. This suggests, in addition to medical treatment, CVAP should be withdrawn after infection onset.     

PPARG Pro12Ala genotype and risk of cognitive decline in elders? Maybe with diabetes

The Pro12Ala polymorphism of peroxisome proliferator-activated receptor-gamma (PPARG; NCBI dbSNP rs1801282) has been associated with preservation of cognitive function, decreased risk of diabetes, and increased risk of obesity. We attempted to replicate these associations, testing cognitive function and lifetime cognitive change in 519 participants who took the same cognitive test at ages 11 and 79 years. Scores were also available for other cognitive tests at age 79 years, along with history of diabetes, current Body Mass Index (BMI), and other disease and demographic variables. Pro12Ala carrier status was not directly associated with diabetes history or BMI. In carriers who contracted diabetes despite carrying the protective allele, cognitive decline as measured by one test was significantly greater than in other groups. Only six individuals fell into this group; the other cognitive tests did not show this effect. This sample did not replicate the direct association of the PPARG Pro12Ala allele with diabetes status or preserved cognitive function. The data did suggest that risk of cognitive decline is greater when Pro12Ala carriers contract diabetes.     

Childhood thyroid autoimmunity and relation to islet autoantibodies in children at risk for type 1 diabetes in the diabetes prediction in skåne (DiPiS) study

Abstract

Background: The aim was to determine prevalence and age at seroconversion of thyroid autoimmunity in relation to islet autoantibodies, gender and HLA-DQ genotypes in children with increased risk for type 1 diabetes followed from birth.

Methods: In 10-year-old children (n?=?1874), blood samples were analysed for autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TGAb), glutamic acid decarboxylase 65 (GADA), Zink transporter 8 (ZnT8R/W/QA), insulinoma-associated protein-2 (IA-2A), insulin (IAA) and HLA-DQ genotypes. Prospectively collected samples from 2 years of age were next analysed for TPOAb, and TGAb and, finally, in confirming samples at 11–16 years of age along with TSH and FT4. Frequencies were tested with Chi-square or Fischer’s exact tests, autoantibody levels with Wilcoxon and correlations between autoantibody levels with Spearman’s rank correlation test.

Results: The prevalence of thyroid autoimmunity was 6.9%, overrepresented in girls (p?<?.001) also having higher TPOAb levels at 10 years (p?=?.049). TPOAb was associated with GADA (p?=?.002), ZnT8R/W/QA (p?=?.001) and IA-2A (p?=?.001) while TGAb were associated with ZnT8R/W/QA (p?=?.021). In boys only, TPOAb were associated with GADA (p?=?.002), IA-2A (p?=?.001), ZnT8R/W/QA (p?=?.001) and IAA (p?=?.009), and TGAb with GADA (p?=?.013), IA-2A (p?=?.005) and ZnT8R/W/QA (p?=?.003). Levels of IA-2A correlated to both TPOAb (p?=?.021) and to TGAb (p?=?.011). In boys only, levels of GADA and TGAb correlated (p?=?.009 as did levels of IA-2A and TPOAb (p?=?.013). The frequency and levels of thyroid autoantibodies increased with age. At follow-up, 22.3% had abnormal thyroid function or were treated with thyroxine.

Conclusions: Thyroid autoimmunity and high TPOAb levels were more common in girls. In contrast, in boys only, there was a strong association with as well as correlation between levels of thyroid and islet autoantibodies. It is concluded that while girls may develop autoimmune thyroid disease (AITD) independent of islet autoantibodies, the risk for thyroid disease in boys may be linked to concomitant islet autoimmunity.     

Recommendations from the EGAPP Working Group: does genomic profiling to assess type 2 diabetes risk improve health outcomes?

Summary of recommendationsThe Evaluation of Genomic Applications in Practice and Prevention (EGAPP) Working Group (EWG) found insufficient evidence to recommend testing for predictive variants in 28 variants (listed in Table 1) to assess risk for type 2 diabetes in the general population, on the basis of studies in populations of northern European descent. The EWG found that the magnitude of net health benefit from the use of any of these tests alone or in combination is close to zero. The EWG discourages clinical use unless further evidence supports improved clinical outcomes.The EWG found insufficient evidence to recommend testing for the TCF7L2 gene to assess risk for type 2 diabetes in high-risk individuals. The EWG found that the magnitude of net health benefit from the use of this test is close to zero. The EWG discourages clinical use unless further evidence supports improved clinical outcomes.On the basis of the available evidence for both the scenarios, the overall certainty of net health benefit is deemed “low.”RationaleIt has been suggested that genomic profiling in the general population or in high-risk populations for type 2 diabetes might lead to management changes (e.g., earlier initiation or higher rates of medical interventions, or targeted recommendations for behavioral change) that improve type 2 diabetes outcomes or prevent type 2 diabetes. The EWG found no direct evidence to support this possibility; therefore, this review sought indirect evidence aimed at documenting the extent to which genomic profiling alters type 2 diabetes risk estimation, alone and in combination with traditional risk factors, and the extent to which risk classification improves health outcomes.Analytic validityAssay-related evidence on available genomic profiling tests was deemed inadequate. However, on the basis of existing technologies that have been or may be used, the analytic sensitivity and specificity of tests for individual gene variants might be at least satisfactory.Clinical validityTwenty-eight candidate markers were evaluated in the general population. Evidence on clinical validity was rated inadequate for 24 of these associations (86%) and adequate for 4 (14%). Inadequate grades were based on limited evidence, poor replication, existence of possible biases, or combinations of these factors. Type 2 diabetes genomic profiling provided areas under the receiver operator characteristics curve of 55%–57%, with 4, 8, and 28 genes. Only TCF7L2 had convincing evidence of an association with type 2 diabetes with an odds ratio of 1.39 (95% confidence interval: 1.33–1.46).TCF7L2 was evaluated for high-risk populations, and the overall odds ratio was 1.66 (95% confidence interval: 1.22–2.27) for association with progression to type 2 diabetes.Clinical utilityNo studies were available to provide direct evidence on the balance of benefits and harms for genetic profiling for type 2 diabetes alone or in addition to traditional risk factors in the general population.Evidence for high-risk populations and TCF7L2 was inadequate on the basis of two identified studies. These studies found close to zero additional benefit with the addition of genomic markers to traditional risk factors (diet, body mass index, and glucose tolerance).Contextual issuesPrevention of type 2 diabetes is a public health priority. Improvements in the outcomes associated with genomic profiling could have important impacts. Traditional risk factors (e.g., body mass index, weight, fat mass, and exercise) have an advantage in clinical screening and risk assessment strategies because they measure the actual targets for therapy (e.g., fasting plasma glucose and medical interventions). To be useful in predicting disease risk, genomic testing should improve the predictive value of these traditional risk factors. Some issues important for clinical utility remain unknown, such as the level of risk that changes intervention, whether long-term disease outcomes will improve, how individuals being tested will understand/respond to test results and interact with the health-care system, and whether testing will motivate behavior change or amplify potential harms.Genet Med 2013:15(8):612–617     

HLA DR/DQ alleles and risk of type I diabetes in childhood: a population–based case–control study

Abstract The objective was to evaluate HLA DR/DQ alleles and their risk factor for type 1 diabetes in the Abruzzo region (central Italy). Sixty incident cases from the Abruzzo region were studied together with 120 unrelated control subjects living in the same administrative areas. The relative risk of diabetes associated with the alleles under study was calculated by deriving the odds ratio (OR) maximum likelihood estimates and their 95% confidence intervals (CI) by the exponentiation of the logistic regression beta–parameter. The combination DRB1*03/DQA1*0501/DQB1*0201 was found in 20.0% of patients and 7.1% of the control subjects, conferring an OR of 4.04 and a CI of 1.97–8.49. The combination DRB1*04/DQA1*0301/DQB1*0302 was found in 23.3% of diabetic patients and 6.7% of controls, giving an OR of 5.69 and a CI of 2.77–12.05. DRB1*11/DQA1*0505/DQB1*0301 and DQA1*0505/DQB1*0301 were negatively associated with type 1 diabetes (OR=0.27, CI 0.11–0.57; OR=0.07, CI 0.02–0.19). The DQA1 genotype at risk was found to be DQA1*0301/DQA1*0501: OR=23.80, CI 2.97–190.89, as it occurred with the highest frequency in the patient group. The DQB1 genotype at risk was found to be DQB1*0201/DQB1*0302, which occurred in 13.3% of patients but in only 1.1% of the control group (OR=29.75, CI 5.36–549.25). Our results shed further light on the risk of development of this disease during a specific time period in an area where the overall incidence of type 1 diabetes is known.     

What do we know about gestational diabetes mellitus and risk for postpartum depression among ethnically diverse low-income women in the USA?

Many women develop postpartum mental health symptoms, ranging from the maternity blues to clinically diagnosed postpartum depression (PPD). Substantial literature supports an association between depression and type 2 diabetes, but there is limited literature regarding to what extent this relationship pertains to gestational diabetes (GDM) and postpartum depression. Review of the literature regarding GDM and PPD with a particular focus on describing the prevalence of PPD among women who may be at increased risk for GDM, including low-income and ethnic minority groups, was performed. Literature searches were conducted across four databases for studies reporting postpartum mental health outcomes (including postpartum depression, behavioral symptoms, mental disorders, mood, anxiety, quality of life) following a diagnosis of GDM. Studies including subgroups of women with GDM were included if postpartum mental health outcomes were reported. Of the 245 abstracts identified, ten studies were included in the final review. Findings suggest that PPD was high among low-income, ethnic minority women. Additional research is required to understand the complex relationship between GDM and PPD among low-income women, with the ultimate goal of implementing tailored interventions to address their medical and psychiatric needs.     

Does diabetes hide osteoarthritis pain?

Clinical practice and research efforts related to the highly prevalent and disabling disease, osteoarthritis (OA), have long been hampered by an inadequate case definition. Much of the difficulty is due to a lack of agreement between X-rays evidence of OA and a patient's report of pain at that site. Such discordance between reported pain and radiographic evidence of OA has been attributed to several factors. This paper proposes another possible explanation, for at least a portion of such patients. It is hypothesized that an insidiously increasing diabetic neuropathy, particularly in the lower extremity, while first causing some pain, may gradually inhibit the ability to feel pain which might have otherwise been reported by those patients without neuropathy. Many of these patients with early stage glucose dysmetabolism will proceed to develop overt type 2 diabetes; however, the pain-inhibiting neuropathy caused by glucose metabolism dysfunction may manifest long before such a diagnosis. The high prevalence of diabetes and pre-diabetic conditions, especially among the aged population, could mean that a substantial number of individuals with osteoarthritis will have both diseases to varying degrees over time. Validating and quantifying this hypothesized association would be useful to millions of persons and would significantly impact both research and clinical practice dealing with these major diseases of older persons.     

Thoroughly modern risk prediction?

Researchers use a data-driven technique called statistical learning to fashion risk prediction algorithms for clinical situations with low event rates.     

Tagging single nucleotide polymorphisms in the PPAR-γ and RXR-α gene and type 2 diabetes risk:a case-control study of a Chinese Han population

Peroxisome proliferator-activated receptor (PPAR-γ),which is mainly involved in adipocyte differentiation, has been suggested to play an important role in the pathogenesis of insulin resistance and atherosclerosis. We investigated the frequencies of two common tagging polymorphisms of the PPAR-γ gene and two of PPAR-α with minor allele frequency (MAF)≥ 0.05 in the Chinese Han population and analyzed the correlation between the different genotypes and the risk of type 2 diabetes mellitus (T2DM). TaqMan assay was performed to test the genotypes in T2DM patients (n = 1,105) and normal controls (n = 1,107). Serum adiponectin concentration was measured by ELISA kit. The variant genotypes rs17817276GG, rs3856806CT and rs3856806CT/TT of PPAR-γ were associated with T2DM, P = 0.023,0.037 and 0.018, respectively. Furthermore, the prevalence of haplotype GT in PPAR-γ was less frequent in the case subjects (0.3%) than in the controls (1.9%) [P < 0.001,OR(95%CI)=0.13 (0.06-0.31)]. Patients with genotype TT of rs3856806 had a higher serum level of adiponectin than those with the genotype CC and CT (P = 0.031 and 0.038, respectively). There was no statistically significant difference between patients and controls in genotype distribution of rs6537944 and rs1045570 of the RXR-α gene. The present study suggests that the variant genotypes in the PPAR-γ gene could decrease the risk for the development of T2DM in the Chinese Han population.     

Racial differences in the interaction between family history and risk factors associated with diabetes in the National Health and Nutritional Examination Survey, 1999–2004

PurposeWe sought to determine whether the association between family history, a surrogate for genetic predisposition, and diabetes was modified by any known diabetes risk factors and if these relationships were constant across different ethnic groups.MethodsWe examined 10,899 adults from the National Health and Nutrition Examination Survey (1999–2004) to identify interactions between family history and clinical, demographic, and lifestyle variables for the outcome of diabetes using logistic regression analysis in racial/ethnic subgroups.ResultsThere was significant heterogeneity by race/ethnicity in the interaction between covariates and family history in relation to diabetes. In black (P = 0.0001) and Hispanic (P = 0.013), but not white (P = 0.75) subgroups, high-familial risk was a strong risk factor for diabetes among lean individuals but less so among overweight or obese subjects. Among blacks, high-familial risk conferred a 20-fold increased odds of diabetes among lean subjects and only a sixfold increased odds among obese individuals.ConclusionsThese findings suggest possible race/ethnic-specific differences in gene by environment interaction and identify body mass index as an important effect modifier of familial risk in diabetes in non-white populations. These findings may help guide future genetic studies and improve the utility of family history as a public health screening tool.     

Streptozotocin induced diabetes in minipig: a case report of a possible model for type 1 diabetes?

Studies on the pathogenic process in type 1 diabetes are often performed in animal models. Low-dose administration of streptozotocin has been used to induce diabetes with pathological alterations similar to human type 1 diabetes in the animals. Rodent models are frequently used but there is a need of developing new models including larger animals. In this study we wanted to investigate to what extent a minipig was sensitive to low-dose streptozotocin for induction of diabetes with features of human Type I diabetes. A female G?ttingen minipig received two low-doses (40 mg/kg) of streptozotocin with an 11-day interval. Serum was analysed for the presence of the enzyme glutamic acid decarboxylase, isoform 65, (GAD65) and autoantibodies against glutamic acid decarboxylase, isoform 65 (GAD65A), isoform 67 (GAD67A), insulinoma antigen 2 (IA-2) and insulin (IAA). Pancreas tissue was fixated in formaldehyde and was sent for pathoanatomical examination. The minipig became hyperglycaemic after the second injection of streptozotocin. The pathoanatomical examination showed atrophy of the beta-cell population, depletion of insulin with preserved glucagon content. There was no sign of insulitis. Both GAD65 and GAD65A were detected while GAD67A and IAA were absent. It is concluded that chronic diabetes developed after low-dose streptozotocin injection in a female minipig with the characteristics of the end stage of type 1 diabetes. This pilot study suggests that minipigs show promise as a model to induce diabetes by injections of low-dose streptozotocin.     

Tuberculosis and diabetes mellitus – an underappreciated association

The current review presents up-to-date knowledge on tuberculosis (TB) in diabetic patients. On the basis of available literature, there is little doubt about the close relationship between these two conditions. Diabetes mellitus in this association may still contribute substantially to the burden of TB and negatively affect control of the latter. Chronic hyperglycemia at least to some extent may alter the clinical manifestation, radiological appearance, treatment outcome and prognosis of TB. Although the pathogenesis is not clear, diabetes may impair both innate and adaptive immune responses to Mycobacterium tuberculosis. Eventually, effective screening and dual management of the diseases have to be addressed both in low- and high-income countries in order to limit the negative effects of the forthcoming global diabetes epidemic.     

Genetic variation within the NR1H2 gene encoding liver X receptor β associates with insulin secretion in subjects at increased risk for type 2 diabetes

The liver X receptors (LXRs)-α and -β play a crucial role in control of insulin production and secretion in pancreatic β-cells. We hypothesized that common variants in the NR1H2 and NR1H3 genes, encoding LXR-β and -α, respectively, may alter pancreatic β-cell function. One thousand five hundred seventy-four subjects of European ancestry with elevated risk for type 2 diabetes were genotyped for the two NR1H2 single nucleotide polymorphisms (SNPs) rs2248949 and rs1405655 and for the four NR1H3 SNPs rs11039149, rs3758673, rs12221497 and rs2279238, and association studies with metabolic traits were performed. Metabolic characterization comprised an oral glucose tolerance test (OGTT) in all participants and, in addition, a hyperinsulinemic–euglycemic clamp and an intravenous glucose tolerance test (IVGTT) in subsets. One hundred per cent of common genetic variation (minor allele frequency ≥1%) within the NR1H2 and NR1H3 loci (D′ = 1.0; r2 ≥ 0.8) were covered by the six chosen tagging SNPs. NR1H2 rs2248949 was nominally associated with OGTT-derived first-phase insulin secretion and proinsulin conversion to insulin and significantly associated with the AUC of insulin levels during the IVGTT (p = 0.007) after adjustment for age, gender, BMI and insulin sensitivity in the dominant model, with the minor allele conferring reduced pancreatic β-cell function to the carriers. In subjects of European ancestry at increased risk for type 2 diabetes, common variation within the NR1H2 gene impaired insulin secretion, which may facilitate the development of type 2 diabetes.