Comparison of the seasonal pattern in the clinical onset of IDDM in Finland and Sardinia

Multifaceted Roles of Vitamin D for Diabetes: From Immunomodulatory Functions to Metabolic Regulations

Numerous studies have established associations between vitamin D and diabetes. The vitamin D receptor is widely distributed throughout the human body, including in pancreatic beta cells (β-cells), hepatocytes, and immune cells. Therefore, vitamin D's effect on the risk, progression, or complications of diabetes may be mediated through various mechanisms. These include the regulation of insulin secretion or sensitivity and modulation of β-cell function and its immunomodulatory and anti-inflammatory effects. This review extensively explores the relationship between vitamin D status and diabetes, as well as the preventive or therapeutic effects of vitamin D supplementation on diabetes from human studies. Additionally, it examines in detail the impact of vitamin D on immune and inflammatory responses in the diabetic milieux and β-cell function to better understand the underlying mechanisms through which vitamin D influences diabetes.

Research Progress on the Relationship between Vitamins and Diabetes: Systematic Review

Diabetes is a serious chronic metabolic disease that causes complications over time, bringing serious public health challenges that affect different countries across the world. The current clinical drugs for diabetes may lead to adverse effects such as hypoglycemia and liver and abdominal distension and pain, which prompt people to explore new treatments for diabetes without side effects. The research objective of this review article is to systematically review studies on vitamins and diabetes and to explain their possible mechanism of action, as well as to assess the role of vitamins as drugs for the prevention and treatment of diabetes. To achieve our objective, we searched scientific databases in PubMed Central, Medline databases and Web of Science for articles, using "vitamin" and "diabetes" as key words. The results of numerous scientific investigations revealed that vitamin levels were decreased in humans and animals with diabetes, and vitamins show promise for the prevention and/or control of diabetes through anti-inflammation, antioxidation and the regulation of lipid metabolism. However, a few studies showed that vitamins had no positive effect on the development of diabetes. Currently, studies on vitamins in the treatment of diabetes are still very limited, and there are no clinical data to clarify the dose-effect relationship between vitamins and diabetes; therefore, vitamins are not recommended as routine drugs for the treatment of diabetes. However, we still emphasize the great potential of vitamins in the prevention and treatment of diabetes, and higher quality studies are needed in the future to reveal the role of vitamins in the development of diabetes.

Diabetic Ketoacidosis in Northern Jordan: Seasonal Morbidity and Characteristics of Patients

Purpose

This study aimed to characterize adult patients admitted with diabetic ketoacidosis (DKA) in northern Jordan.

Methods

The study examined medical records of patients diagnosed with DKA from January 2015 to April 2018. Variables analyzed included diabetes type, precipitating illness, admission month, hospital length of stay, and biochemical markers.

Results

Out of 232 admissions with DKA, 70% were diagnosed with type 2 diabetes, and 56% were females. 12% of admissions had a new diagnosis of diabetes, of which 51% had type 2 diabetes. Sepsis (48%), Non-adherence (26%), and diabetic foot infections (18%) were the most encountered precipitating factors for DKA in T1DM. As for T2DM, sepsis (52%), acute coronary syndrome (12%), and pancreatitis (8%) were the most precipitating factors for DKA. High urea levels, high creatinine levels, low phosphorous levels, low hemoglobin levels, and high platelet counts were associated with a longer hospital stay for type 1 diabetes. For type 2 diabetes, low pH on admission, old age, and high Hb A1c within 6 months of admission were factors associated with a prolonged hospital stay. The study found a significant peak of admissions for DKA in both type 1 and type 2 patients in the winter and spring months (Pearson P-value= 0.0013).

Conclusion

The results of the present study highlight the seasonal variation in the frequency of DKA hospitalizations. It also highlights sepsis as the most frequent precipitating factor of DKA in both type 1 and type 2 DM patients.

Antibody Cross-Reactivity in Auto-Immune Diseases

Autoimmunity is defined by the presence of antibodies and/or T cells directed against self-components. Although of unknown etiology, autoimmunity commonly is associated with environmental factors such as infections, which have been reported to increase the risk of developing autoimmune diseases. Occasionally, similarities between infectious non-self and self-tissue antigens may contribute to immunological cross-reactivity in autoimmune diseases. These reactions may be interpreted as molecular mimicry, which describes cross-reactivity between foreign pathogens and self-antigens that have been reported to cause tissue damage and to contribute to the development of autoimmunity. By focusing on the nature of antibodies, cross-reactivity in general, and antibody-antigen interactions, this review aims to characterize the nature of potential cross-reactive immune reactions between infectious non-self and self-tissue antigens which may be associated with autoimmunity but may not actually be the cause of disease onset.

Examining the associations between COVID-19 infection and pediatric type 1 diabetes

INTRODUCTION

The COVID-19 pandemic represents an unprecedented challenge for public health worldwide, not only for the very high number of cases and deaths but also due to a wide variety of indirect consequences. Among these, the possible relationship between SARS-CoV-2 infection and type 1 diabetes (T1D) in pediatric age has aroused notable interest in the scientific community.

AREAS COVERED

This perspective article aims to focus on the epidemiological trend of T1D during the pandemic, the diabetogenic role of SARS-CoV-2, and the influence of preexisting T1D on COVID-19 outcomes.

EXPERT OPINION

The incidence of T1D has considerably changed during the COVID-19 pandemic, but any direct role of SARS-CoV-2 is uncertain. It is more likely that SARS-CoV-2 infection acts as an accelerator of pancreatic β-cell immunological destruction, which is activated by known viral triggers whose spread has been abnormal during these pandemic years. Another interesting aspect to consider is the role of immunization as a potential protective factor both for T1D development and the risk of severe outcomes in already diagnosed patients. Future studies are still required to address unmet needs, including the early use of antiviral drugs to reduce the risk of metabolic decompensation in children with T1D.

Variation in the incidence of type 1 diabetes mellitus in children and adolescents by world region and country income group: A scoping review

INTRODUCTION

Around 18.7 million of the 537 million people with diabetes worldwide live in low-income and middle-income countries (LMIC), where there is also an increase in the number of children, adolescents, and young adults diagnosed with type 1 diabetes (T1D). There are substantial gaps in data in the current understanding of the epidemiological patterns and trends in incidence rates of T1D at the global level.

METHODS

We performed a scoping review of published studies that established the incidence of T1D in children, adolescents, and young adults aged 0-25 years at national and sub-national levels using PubMed, Embase and Global Health. Data was analyzed using R programming.

RESULTS

The scoping review identified 237 studies which included T1D incidence estimates from 92 countries, revealing substantial variability in the annual incidence of T1D by age, geographic region, and country-income classification. Highest rates were reported in the 5-9 and 10-14 year age groups than in the 0-4 and 15-19 year age groups, respectively. In the 0-14 year age group, the highest incidence was reported in Northern Europe (23.96 per 100,000), Australia/New Zealand (22.8 per 100,000), and Northern America (18.02 per 100,000), while the lowest was observed in Melanesia, Western Africa, and South America (all < 1 per 100,000). For the 0-19 year age group, the highest incidence was reported in Northern Europe (39.0 per 100,000), Northern America (20.07 per 100,000), and Northern Africa (10.1 per 100,000), while the lowest was observed in Eastern and Western Africa (< 2 per 100,000). Higher incidence rates were observed in high-income countries compared to LMICs. There was a paucity of published studies focusing on determining the incidence of T1D in LMICs.

CONCLUSION

The review reveals substantial variability in incidence rates of T1D by geographic region, country income group, and age. There is a dearth of information on T1D in LMICs, particularly in sub-Saharan Africa, where incidence remains largely unknown. Investment in population-based registries and longitudinal cohort studies could help improve the current understanding of the epidemiological trends and help inform health policy, resource allocation, and targeted interventions to enhance access to effective, efficient, equitable, and responsive healthcare services.

Plasma-derived exosomal mRNA profiles associated with type 1 diabetes mellitus

BACKGROUND

Exosomes carry various types of transcripts, such as messenger RNAs (mRNAs), and play an important role in mediating cell-to-cell communication, thus influencing multiple physiological and pathological processes. However, the role of exosomal mRNAs in T1DM is largely unknown. Here, we aimed to identify the plasma-derived exosomal mRNA expression profiles in T1DM and to explore their potential biological functions in T1DM.

MATERIALS AND METHODS

Plasma-derived exosomes were isolated from 10 patients with T1DM and 10 age- and sex-matched control subjects by size exclusion chromatography methods. Transmission electron microscopy, nanoparticle tracking analysis, and western blot analysis confirmed the presence of exosomes. The exosomal mRNAs were analyzed using the Illumina HiSeq platform. Six differentially expressed mRNAs (DEMs) were randomly selected to determine the expression level by quantitative real-time PCR (qRT-PCR) in a larger cohort (T1DM subjects N=40; control subjects N=40). The biological functions of DEMs were predicted by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Protein-protein interaction networks were constructed to explore the potential associations among DEMs.

RESULTS

In total, 112 DEMs were identified in T1DM, among which 66 mRNAs were upregulated and 46 mRNAs were downregulated. Four of six candidate exosomal mRNAs were successfully validated by qRT-PCR. Bioinformatics analysis indicated that these mRNAs were most significantly involved in positive regulation by host viral transcription (GO enrichment analysis) and oxidative phosphorylation (KEGG pathway analysis).

CONCLUSIONS

Our study reported the plasma-derived exosomal mRNA expression profiles of T1DM for the first time. The identified DEMs might be associated with the pathogenesis of T1DM, and some DEMs have the potential to serve as biomarkers and therapeutic targets for T1DM.

Vitamin D and Immunity in Infants and Children

The last couple of decades have seen an explosion in our interest and understanding of the role of vitamin D in the regulation of immunity. At the molecular level, the hormonal form of vitamin D signals through the nuclear vitamin D receptor (VDR), a ligand-regulated transcription factor. The VDR and vitamin D metabolic enzymes are expressed throughout the innate and adaptive arms of the immune system. The advent of genome-wide approaches to gene expression profiling have led to the identification of numerous VDR-regulated genes implicated in the regulation of innate and adaptive immunity. The molecular data infer that vitamin D signaling should boost innate immunity against pathogens of bacterial or viral origin. Vitamin D signaling also suppresses inflammatory immune responses that underlie autoimmunity and regulate allergic responses. These findings have been bolstered by clinical studies linking vitamin D deficiency to increased rates of infections, autoimmunity, and allergies. Our goals here are to provide an overview of the molecular basis for immune system regulation and to survey the clinical data from pediatric populations, using randomized placebo-controlled trials and meta-analyses where possible, linking vitamin D deficiency to increased rates of infections, autoimmune conditions, and allergies, and addressing the impact of supplementation on these conditions.

Influence of Vitamin D on Islet Autoimmunity and Beta-Cell Function in Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease leading to immune-mediated destruction of pancreatic beta cells, resulting in the need for insulin therapy. The incidence of T1D is increasing worldwide, thus prompting researchers to investigate novel immunomodulatory strategies to halt autoimmunity and modify disease progression. T1D is considered as a multifactorial disease, in which genetic predisposition and environmental factors interact to promote the triggering of autoimmune responses against beta cells. Over the last decades, it has become clear that vitamin D exerts anti-inflammatory and immunomodulatory effects, apart from its well-established role in the regulation of calcium homeostasis and bone metabolism. Importantly, the global incidence of vitamin D deficiency is also dramatically increasing and epidemiologic evidence suggests an involvement of vitamin D deficiency in T1D pathogenesis. Polymorphisms in genes critical for vitamin D metabolism have also been shown to modulate the risk of T1D. Moreover, several studies have investigated the role of vitamin D (in different doses and formulations) as a potential adjuvant immunomodulatory therapy in patients with new-onset and established T1D. This review aims to present the current knowledge on the immunomodulatory effects of vitamin D and summarize the clinical interventional studies investigating its use for prevention or treatment of T1D.

Type 1 diabetes and viral infections: What is the relationship?

Type 1 diabetes (T1D) is the most common chronic metabolic disorder in children. Epigenetic and environmental factors capable of altering the penetrance of major susceptibility genes or capable of increasing the penetrance of low-risk genes are currently thought to play a role in triggering autoimmunity and T1D development. This paper discusses the current knowledge of the role of viruses in T1D. Most studies that have evaluated the potential association between viral infections and T1D have indicated that it is highly likely that some of these infectious agents play a role in T1D development. However, most T1D cases are immune-mediated, and it is supposed that the initial viral infection is capable of creating, in genetically predisposed subjects, a particular condition in which chronic local inflammation occurs through the persistence of the infecting virus in pancreatic tissue and the activation of autoimmunity by means of molecular mimicry, bystander activation, or both. Theoretically, this knowledge could lead to possible prophylaxis and therapy for T1D. Further studies devoted to evaluating which infectious agents are linked to T1D and which immune mechanisms induce or protect against the disease are needed before adequate prophylactic and therapeutic measures can be developed.

Vitamin D: not just the bone. Evidence for beneficial pleiotropic extraskeletal effects

Vitamin D is a fat-soluble vitamin and a steroid hormone that plays a central role in maintaining calcium-phosphorus and bone homeostasis in close interaction with parathyroid hormone, acting on its classical target tissues, namely, bone, kidney, intestine, and parathyroid glands. However, vitamin D endocrine system regulates several genes (about 3 % of the human genome) involved in cell differentiation, cell-cycle control, and cell function and exerts noncalcemic/pleiotropic effects on extraskeletal target tissues, such as immune and cardiovascular system, pancreatic endocrine cells, muscle, and adipose tissue. Several studies have demonstrated the role of vitamin D supplementation in the prevention/treatment of various autoimmune diseases and improvement of glucose metabolism, muscle, and adipose tissue function. Hence, this review aims to elucidate the effects of vitamin D on extraskeletal target tissues and to investigate the potential therapeutic benefit of vitamin D supplementation among a broad group of pathological conditions, especially with regard to metabolic and autoimmune diseases. In addition, we focused on the best daily intakes and serum levels of vitamin D required for extraskeletal benefits which, even if still controversial, appear to be higher than those widely accepted for skeletal effects.

Are low sun exposure and/or vitamin D risk factors for type 1 diabetes?

Ultraviolet radiation and vitamin D, with their known immunosuppressive effects, have the potential to delay or inhibit type 1 diabetes.

Low serum vitamin-D status is associated with high prevalence and early onset of type-1 diabetes mellitus in Kuwaiti children

Background

Type 1 diabetes mellitus (T1DM) is highly prevalent in Kuwait with incidence of around 40.1/100,000 individuals. Evidence indicate that vitamin D plays an important role in modulating the immune system and could thus impact the onset and high prevalence of T1DM. We report serum vitamin D levels in Kuwaiti children with T1DM and non-diabetic controls to explore its relationship with prevalence and onset of the disease.

Methods

This study included 216 Kuwaiti Arab children with T1DM. The diagnosis of T1DM was based on the ISPAD criteria. The control subjects (204 Kuwaitis) were age and gender matched, healthy, non-diabetic, and had no close relative with T1DM. Vitamin D levels were determined in serum using an enzyme immunoassay (EIA) method.

Results

The age of onset of T1DM was <4y in 20 % of the T1DM cases, between 4 and 6y in 28 % cases and >6y in 52 % patients. In T1DM patient group, 84 % subjects were found to be deficient in serum vitamin D level compared to 77 % of the controls (p = 0.046). Collectively, the deficient and insufficient vitamin D status was detected in 99 % of the T1DM patients compared to 92 % of the controls (p = 0.027). The mean serum vitamin D levels were found to be significantly different in early onset cases (age <4y) compared to the late onset sub-group (p = 0.001). A significant correlation was found between some elements of socioeconomic status, SES (i.e. parent’s profession and family’s income) and lower vitamin D levels in Kuwaiti T1DM children. There was no significant difference between mean serum vitamin D levels during winter and summer months in the T1DM patients.

Conclusions

The proportion of cases with a deficient vitamin D status was significantly high in Kuwaiti T1DM children compared to the controls. The serum vitamin D levels were found to be significantly different in early onset and late onset T1DM patients. Therefore, serum vitamin D status can be considered an important contributor in high prevalence of T1DM in Kuwaiti children.

Temporal variation of diabetic ketoacidosis and hypoglycemia in adults with type 1 diabetes: A nationwide cohort study

BACKGROUND

Seasonality in health outcomes has long been recognized for conditions such as colds and flus. The aim of the present study was to determine whether hospitalizations for acute complications of type 1 diabetes (T1D) vary by month and season.

METHODS

An observational study was performed of national administrative health data. Hospitalizations for acute complications in adults (aged ≥18 years) with T1D were identified using ICD-10 (Canadian revision) codes between 2004 and 2010. Monthly and seasonal counts per year were determined for the study period. For each acute complication, the ratio of the number of observed hospitalizations/expected number of hospitalizations was calculated for each month and season per year, adjusting for varied lengths of month, season, and year.

RESULTS

In all, there were 21 568 hospitalizations for diabetic ketoacidosis (DKA) and 5349 hospitalizations for hypoglycemia during the study period. December had higher than expected hospitalizations for DKA and March had higher than expected hospitalizations for hypoglycemia. There did not appear to be variation for either DKA or hypoglycemia hospitalizations by season.

CONCLUSIONS

The results of the present study suggest temporal variation in hospitalizations for DKA and hypoglycemia, and therefore signal important times of patient vulnerability. Potential mechanisms underlying this pattern warrant further examination. Prevention strategies and resources for patients with T1D may need to be increased at specific times during the year.

Influence of diabetic state and vitamin D deficiency on bone repair in female mice

Type 1 diabetes is associated with an increased fracture risk, an impaired fracture healing, and an increased vitamin D insufficiency. However, the role of vitamin D in diabetic bone repair process remains unclear. We therefore examined the effects of vitamin D deficiency on the impaired bone repair in streptozotocin (STZ)-induced diabetes using female mice. Diabetes was induced by STZ injection into female mice after feeding with normal or vitamin D-deficient diet for 6weeks from the age of 4weeks. A femoral bone defect was induced in mice 4 weeks after induction of diabetes. The repair of damaged site on the femur was significantly delayed at days 7 and 10 after bone defect by diabetic state in mice, as assessed by quantitative computed tomography, while vitamin D deficiency did not affect the bone repair both in mice with normal and diabetic state. The decreases in bone mineral density (BMD) at cortical and trabecular bone by diabetic state were significantly augmented by vitamin D deficiency in tibia at the undamaged side in mice. Diabetic state blunted the levels of osteogenic and chondrogenic genes enhanced by vitamin D deficiency. Moreover, vitamin D deficiency significantly aggravated the decreases in osteocalcin and IGF-1 mRNA by diabetic state. In conclusion, our study showed that vitamin D deficiency aggravates the decrease in BMD by diabetic state in female mice, although vitamin D deficiency did not affect bone repair delayed by diabetic state.

Serum vitamin D status in children and adolescence with diabetes according to season and age

PURPOSE

It is known that children with diabetes have more severe vitamin D deficiency than healthy children. This study aimed to investigate serum vitamin D status and analyze the relationships between serum vitamin D levels and clinical parameters in children with diabetes.

METHODS

We checked serum vitamin D levels of children with diabetes aged below 18 years who were treated at our Department of Pediatrics between December 2011 and February 2012 (winter) as well as between June 2012 and August 2012 (summer). We retrospectively analyzed relationships between their serum vitamin D levels and clinical parameters.

RESULTS

The serum 25-hydroxyvitamin D level in children with diabetes during winter was markedly lower than during summer (10.8±5.1 ng/mL vs. 17.6±5.6 ng/mL); vitamin D deficiency was more prevalent during winter (95% vs. 62%). However, there was no difference between children with diabetes and healthy children. In children with type I diabetes mellitus, among all the clinical parameters, age had the greatest negative correlation with serum vitamin D level.

CONCLUSION

In children with diabetes, serum vitamin D levels showed marked seasonal variation. However, no clear relationship was identified between vitamin D deficiency and diabetes. This was because the control group had an equally high vitamin D deficiency rate. Additional studies including other clinical parameters after vitamin D supplementation in children with diabetes should be considered.

Vitamin D and diabetes: the odd couple

The beneficial effects of vitamin D supplementation for several health-related issues, including the prevention of diabetes, are a topic of intense discussion. Data from epidemiological studies suggest a correlation between vitamin D deficiency and higher prevalence of both type 1 and type 2 diabetes (T1D and T2D). In animal models, vitamin D deficiency predisposes to diabetes whereas vitamin D supplementation prevents disease. Nevertheless, well-designed clinical intervention studies are lacking. We discuss here the evidence for a role of vitamin D in diabetes and propose that vitamin D deficiency should be avoided, especially in all at-risk people. This should be possible by implementing global guidelines and by focusing on daily dietary supplementation with small doses of vitamin D.

High meat consumption is associated with type 1 diabetes mellitus in a Sardinian case-control study

The large worldwide variation in type 1 diabetes incidence and increasing incidence over time points toward important environmental risk factors. Among them, nutrition plays an important role. The objective was to investigate the relationship between type 1 diabetes and nutritional factors in pregnancy and early in life. We carried out, using semi-quantitative food frequency questionnaires, a retrospective case-control study in 298 children of 0-15 years old, 145 of which were affected by type 1 diabetes. The diet of all children and of their mothers during pregnancy and lactation was assessed. In children, a statistically significant dose-response association between type 1 diabetes and the amount of meat consumption was found while no other nutritional factors were associated with the disease. High meat consumption seems to be an important early in life cofactor for type 1 diabetes development, although these findings need to be confirmed in wider prospective follow-up studies.

Vitamin D: effects on childhood health and disease

Vitamin D is a key nutrient for both healthy children and those with chronic illnesses. Understanding its roles in health and disease has become one of the most important issues in the nutritional management of children. Formal guidelines related to nutrient requirements for vitamin D in healthy children, recommending dietary intakes of 400 IU per day for infants and 600 IU per day for children over 1 year of age, were released by the Institute of Medicine in November 2010. However, application of these guidelines to children with acute and chronic illnesses is less clear. In this Review, we consider major illness categories and specific examples of conditions in children that might be affected by vitamin D. This information can be used in developing both model systems of investigation and clinical trials of vitamin D in children with acute and chronic illnesses.

Vitamin D deficiency: a new risk factor for type 2 diabetes?

Recent compelling evidence suggests a role of vitamin D deficiency in the pathogenesis of insulin resistance and insulin secretion derangements, with a consequent possible interference with type 2 diabetes mellitus. The mechanism of this link is incompletely understood. In fact, vitamin D deficiency is usually detected in obesity in which insulin resistance is also a common finding. The coexistence of insulin resistance and vitamin D deficiency has generated several hypotheses. Some cross-sectional and prospective studies have suggested that vitamin D deficiency may play a role in worsening insulin resistance; others have identified obesity as a risk factor predisposing individuals to exhibit both vitamin D deficiency and insulin resistance. The available data from intervention studies are largely confounded, and inadequate considerations of seasonal effects on 25(OH)D concentrations are also a common design flaw in many studies. On the contrary, there is strong evidence that obesity might cause both vitamin D deficiency and insulin resistance, leaving open the possibility that vitamin D and diabetes are not related at all. Although it might seem premature to draw firm conclusions on the role of vitamin D supplementation in reducing insulin resistance and preventing type 2 diabetes, this manuscript will review the circumstances leading to vitamin D deficiency and how such a deficiency can eventually independently affect insulin sensitivity.

Vitamin D and diabetes

There is no doubt that vitamin D deficiency is the cause of several metabolic bone diseases, but vitamin D status is also linked to many major human diseases including immune disorders. Mounting data strengthen the link between vitamin D and diabetes, in particular T1D and T2D. Despite some inconsistencies between studies that associate serum 25(OH)D levels with the risk of developing T1D or T2D, there seems to be an overall trend for an inverse correlation between levels of 25(OH)D and both disorders. There is also compelling evidence that 1,25(OH)2D regulates b-cell function by different mechanisms, such as influencing insulin secretion by regulating intracellular levels of Ca2+, increasing β-cell resistance to apoptosis, and perhaps also increasing β-cell replication. The capacity of vitamin D, more specifically 1,25(OH)2D, to modulate immune responses is of particular interest for both the therapy and prevention of diabetes. In the case of T1D, vitamin D supplementation in prediabetic individuals could help prevent or reduce the initiation of autoimmune processes possibly by regulating thymic selection of the T-cell repertoire, decreasing the numbers of autoreactive T cells, and inducing Treg cells. Although immune modulation is generally discussed for the treatment of T1D, it is also relevant for T2D. Indeed, recent studies have shown that T2D patients have increased systemic inflammation and that this state can induce β-cell dysfunction and death. Supplementation trials with regular vitamin D for the protection against the development of T1D and T2D have generated some contradictory data, but many weaknesses can be identified in these trials as most were underpowered or open-labeled. However, the overwhelming strength of preclinical data and of the observational studies make vitamin D or its analogues strong candidates for the prevention or treatment of diabetes or its complications. However, proof of causality needs well-designed clinical trials and if positive, adequate dosing, regimen, and compound studies are needed to define the contribution of vitamin D status and therapy in the global diabetes problem. There are many confounding factors that need to be taken into consideration when translating successful vitamin D therapies in animal models into humans, for example, gender, age, lifestyle, and genetic background. To come to solid conclusions on the potential of vitamin D or its analogues in the prevention of or therapy for all forms of diabetes, it is clear that large prospective trials with carefully selected populations and end points will be needed, but should also receive high priority.

Vitamin D and diabetes: its importance for beta cell and immune function

Experimental evidence indicates that vitamin D may play a role in the defense against type 1 diabetes (T1D) as well as type 2 diabetes (T2D). Epidemiological data have established a link between vitamin D deficiency and an increased incidence of both T1D and T2D, whereas early and long-term vitamin D supplementation may decrease the risk of these disorders. The protective effects of vitamin D are mediated through the regulation of several components such as the immune system and calcium homeostasis. However, an increasing amount of evidence suggests that vitamin D also affects beta cells directly thereby rendering them more resistant to the types of cellular stress encountered during T1D and T2D. This review evaluates the role of vitamin D signaling in the pathogenesis of T1D and T2D with a special emphasis on the direct effects of vitamin D on pancreatic beta cells.

The effect of the length of the prodromal period on the metabolic control within the first 2 years in children with diabetic ketoacidosis manifestation

PURPOSE

We investigated the effects of clinical and laboratory properties at the time of the initial application of patients recently diagnosed and presenting metabolic indicators of diabetic ketoacidosis who were given disease prognoses in years 1 and 2 after discharge.

MATERIALS AND METHODS

A total of 94 patients admitted to Bakirkoy Maternity and Children's Diseases Training and Research Hospital with diabetic ketoacidosis and recently diagnosed with type 1 diabetes mellitus were investigated. Patient files were examined within 2 years following discharge.

FINDINGS

All 94 study patients (53.2% male and 46.8% female) presented acidosis, ketonuria and hyperglycemia. While a moderate correlation was detected between the prodromal period and HbA(1c) values in year 1, only a slight correlation was seen in HbA(1c) values in year 2. In addition, a slight correlation was observed between the prodromal period and the number of hospitalizations due to diabetic ketoacidosis in the first year. Again, while a moderate correlation was observed between HbA(1c) values and the number of hospitalizations due to diabetic ketoacidosis in year 1, only a slight correlation was seen in year 2. The prodromal period was directly proportional to patient age.

RESULTS

Hospital admissions may be reduced through appropriate treatment, follow-up and metabolic control of patients with type 1 diabetes mellitus. In addition, we report a relationship between the prodromal period and HbA(1c) values in type 1 diabetes patients.

Role of vitamin D in cardiovascular health

Observational studies strongly associate vitamin D deficiency with a variety of cardiovascular diseases beyond defects in bone and calcium metabolism. Vitamin D has multiple mechanisms that potentially may affect cardiovascular health. Because vitamin D deficiency is common, therapies directed at the replacement of vitamin D may be beneficial. To date however, studies evaluating vitamin D supplementation are few and have not consistently shown benefit. It is possible that the lack of benefit in these studies may have arisen from suboptimal levels of vitamin D supplementation or other unknown factors. Nevertheless, the growing body of observational data and consistent findings of relatively high rates of low vitamin D serum levels warrant further well-designed studies to investigate the relation between vitamin D and cardiovascular health. In conclusion, vitamin D is now recognized as important for cardiovascular health and its deficiency as a potential risk factor for several cardiovascular disease processes.

The Sardinian way to type 1 diabetes

Sardinia and Finland are the "hottest" areas for type 1 diabetes mellitus (T1DM) worldwide. Its genetic and epidemiological background make Sardinia an ideal region for investigating environmental, immunological, and genetic factors related to the etiopathogenesis of T1DM. Consequently, in 1990, the Insulin-Dependent Diabetes Mellitus Sardinia Project was launched in order to map the geographical distribution of T1DM in the island and to investigate preclinical phases of T1DM in a large cohort of people genetically at risk. The final goal would be to design models of prediction and to formulate safe preventive measures, especially addressed to the general population living in areas at high risk.

Sexual dimorphic evolution of metabolic programming in non-genetic non-alimentary mild metabolic syndrome model in mice depends on feed-back mechanisms integrity for pro-opiomelanocortin-derived endogenous substances

Previously, we showed that our post-natal handling model induces pro-opiomelanocortin-derived (POMC) endogenous systems alterations in male mice at weaning. These alterations last up to adult age, and are at the basis of adult hormonal and metabolic conditions similar to mild metabolic syndrome/type-2 diabetes. Here, we evaluate how sex influences post-natal programming in these metabolic conditions. Subjects are adult control (non-handled) female (NHF) and male (NHM) CD-1 mice; adult post-natal handled female (HF) and male (HM) mice. Handling consists of daily maternal separation (10 min) plus sham injection, from birth to weaning (21 days). In adult handled males (90-days old) we find not only POMC-derived hormones alterations (enhanced basal plasma corticosterone (+91%) and ACTH (+109%)) but also overweight (+5.4%), fasting hyperglycemia (+40%), hypertriglyceridemia (+21%), enhanced brain mRNA expression of hydroxysteroid(11-beta)dehydrogenase type-1 (HSD11B1) (+49%), and decreased mRNA-HSD11B2 (-39%). Conversely, uric acid, creatinine, HDL(C), total cholesterol, glucose and insulin incremental area under-the-curve are not affected. In females, post-natal handling does not produce both hormonal and dysmetabolic diabetes-like changes; but handling enhances n3- and n6-poly-unsaturated, and decreases saturated fatty acids content in erythrocyte membrane composition in HF versus NHF. In conclusion, for the first time we show that female sex in mice exerts effective protection against the hypothalamus-pituitary-adrenal homeostasis disruption induced by our post-natal handling model on POMC cleavage products; endocrine disruption is in turn responsible for altered metabolic programming in male mice. The role of sex hormones is still to be elucidated.

Vitamin D and diabetes

Type 1 (T1D) and type 2 (T2D) diabetes are considered multifactorial diseases in which both genetic predisposition and environmental factors participate in their development. Many cellular, preclinical, and observational studies support a role for vitamin D in the pathogenesis of both types of diabetes including: (1) T1D and T2D patients have a higher incidence of hypovitaminosis D; (2) pancreatic tissue (more specifically the insulin-producing beta-cells) as well as numerous cell types of the immune system express the vitamin D receptor (VDR) and vitamin D-binding protein (DBP); and (3) some allelic variations in genes involved in vitamin D metabolism and VDR are associated with glucose (in)tolerance, insulin secretion, and sensitivity, as well as inflammation. Moreover, pharmacologic doses of 1,25-dihydroxyvitamin D (1,25(OH)(2)D), the active form of vitamin D, prevent insulitis and T1D in nonobese diabetic (NOD) mice and other models of T1D, possibly by immune modulation as well as by direct effects on beta-cell function. In T2D, vitamin D supplementation can increase insulin sensitivity and decrease inflammation. This article reviews the role of vitamin D in the pathogenesis of T1D and T2D, focusing on the therapeutic potential for vitamin D in the prevention/intervention of T1D and T2D as well as its complications.

Temporal trends in incidence of Type 1 diabetes between 1986 and 2006 in Brazil

BACKGROUND

Scarce information is available about the variation in the incidence of Type 1 diabetes in the Brazilian population in the last decades.

AIM

The objective of this study was to assess the long-term trends (1986-2006) in the incidence of Type 1 diabetes in Bauru, São Paulo State, Brazil.

SUBJECTS AND METHODS

The annual incidence of Type 1 diabetes (per 100,000 per yr) from 1986 to 2006 was determined in children <or=14 yr of age, using the capture and recapture method.

RESULTS

A total of 176 cases were diagnosed in the study population. The overall incidence was 10.4/100,000 with a range of 2.82/100,000 in 1987 to 18.49/100,000 in 2002 representing a 6.56-fold increase within the same population. The estimated incidence, using the capture and recapture method varied from 2.82/100,000 per yr in 1987 to 27.20/100,000 per yr in 2002, representing a 9.6-fold variation. The global pattern of incidence variation was categorized as high (10-19.99/100,000 per yr), and very high (>or=20/100,000 per yr) in 71.43% of the study-years. Incidence was slightly higher among females, Caucasians, children in the 5-9 yr of age range and belonging to lower socio-economic classes. Most diagnoses were established during the colder months and/or with higher pluviometric indexes.

CONCLUSIONS

The incidence of Type 1 diabetes in children is increasing in Bauru, São Paulo State, Brazil, and the global pattern of incidence was classified as high or very high, mainly in the last 10 yr. All Brazilian regions should be involved in the study.

Seasonal variation of diagnosis of Type 1 diabetes mellitus in children worldwide

AIMS

To determine if there is a worldwide seasonal pattern in the clinical onset of Type 1 diabetes.

METHODS

Analysis of the seasonality in diagnosis of Type 1 diabetes was based on the incidence data in 0- to 14-year-old children collected by the World Health Organization Diabetes Mondiale (WHO DiaMond) Project over the period 1990-1999. One hundred and five centres from 53 countries worldwide provided enough data for the seasonality analysis. The incidence seasonality patterns were also determined for age- and sex-specific groups.

RESULTS

Forty-two out of 105 centres exhibited significant seasonality in the incidence of Type 1 diabetes (P < 0.05). The existence of significant seasonal patterns correlated with higher level of incidence and of the average yearly counts. The correlation disappeared after adjustment for latitude. Twenty-eight of those centres had peaks in October to January and 33 had troughs in June to August. Two out of the four centres with significant seasonality in the southern hemisphere demonstrated a different pattern with a peak in July to September and a trough in January to March.

CONCLUSIONS

The seasonality of the incidence of Type 1 diabetes mellitus in children under 15 years of age is a real phenomenon, as was reported previously and as is now demonstrated by this large standardized study. The seasonality pattern appears to be dependent on the geographical position, at least as far as the northern/southern hemisphere dichotomy is concerned. However, more data are needed on the populations living below the 30th parallel north in order to complete the picture.

Vitamin D and diabetes mellitus

Better understanding of the physiological role of the vitamin-D system, in particular its potential effects on inflammatory and autoimmune conditions as well as on insulin secretion and possibly also on insulin resistance, increased the interest in its potential role in prevention and control of the diabetic condition, both type-1 and -2 diabetes. Both these conditions are associated with inflammation and type-1 diabetes also with an autoimmune pathology. Indeed, animal and human studies support the notion that adequate vitamin-D supplementation may decrease the incidence of type-1 and possibly also of type-2 diabetes mellitus and may improve the metabolic control in the diabetes state. However, the exact mechanisms by which vitamin-D and calcium supplementation exert their beneficial effects are not clear and need further investigation.

Epidemiology of type 1 diabetes and what animal models teach us about the role of viruses in disease mechanisms

There is a consensus among epidemiologists that the worldwide incidence rate of type 1 diabetes has been rising in recent decades. The cause of this rise is unknown, but epidemiological studies suggest the involvement of environmental factors, and viral infections in particular. Data demonstrating a cause-and-effect relationship between microbial infections and type 1 diabetes and how viruses may cause disease in humans are currently lacking. However, new evidence from animal models supports the hypothesis that viruses induce disease via mechanisms linked with innate immune upregulation. In the BioBreeding Diabetes Resistant rat, infection with a parvovirus induces islet destruction via upregulation of the toll-like receptor 9 (TLR9) signaling pathway. Data from mouse models of diabetes implicate TLR2, TLR3, and TLR7 in the disease process. Understanding the link between environmental agents and innate immune pathways involved in early stages of diabetes may advance the design of immune interventions to prevent disease in genetically susceptible individuals.

Seasonal variation in the diagnosis of type 1 diabetes in south-east Sweden

With the aim to survey the seasonal pattern of diagnosis of type 1 diabetes we included all 1903 children <16 years of age and who had been diagnosed with type 1 diabetes between 1977 and 2001 in the south-east of Sweden. To investigate the seasonal pattern a mixture of two cosine functions was included in a logistic regression model. There was a clear seasonal variation over the years (p<0.001). Children in the oldest age group (11-15 years) showed the most obvious seasonal variation (p<0.001). Children with a short duration of symptoms had about the same seasonal variation as children with a long duration. Both children with and without an infection 3 months prior to diagnosis showed significant seasonal variation (p<0.001) although the seasonal pattern differed between the two groups (p<0.001). As the incidence of diabetes increased during the 25 years the study period was divided into periods of 5 years and it was only during the two last periods that significant seasonal variation occurred. There is a clear seasonal variation in diagnosis of type 1 diagnosis in children and the results suggest that children with a less aggressive disease process at diagnosis were most responsible for this variation. Children with and without prior infection showed a different seasonal pattern.

Epidemiological association between some dietary habits and the increasing incidence of type 1 diabetes worldwide

BACKGROUND/AIMS

The variation in incidence of type 1 diabetes (T1D) worldwide is genetically based. However, its increasing incidence is environmentally determined. Our aim was to describe the role of nutritional habits and of gene-nutrient interactions in the rising incidence of TID.

METHODS

We did an ecological study in the 37 world areas were a 3% yearly increase of T1D incidence had been reported, and we calculated through the FAO's Food Balance Sheets the per caput daily supply of milk, meat and cereals from 1961 to 2000 and its correlation with the TID incidence.

RESULTS

The supply of milk and cereals remained almost unchanged, whereas that of meat increased by over 31%. The absolute mean TID increase (number of cases per 100,000 per year) was + 0.32. A significant positive correlation with supply of milk was present from 1961 to 2000, while that with meat and cereals became significant in 1983 and 2000.

CONCLUSION

Our ecological analysis indicates that nutritional factors, and in particular meat consumption, play a role in the incidence of T1D and its increase worldwide. Further experimental and case-control studies are warranted in order to assess the gene-nutrient interactions.

Vitamin D and diabetes

Vitamin D deficiency predisposes individuals to type 1 and type 2 diabetes, and receptors for its activated form-1alpha,25-dihydroxyvitamin D3-have been identified in both beta cells and immune cells. Vitamin D deficiency has been shown to impair insulin synthesis and secretion in humans and in animal models of diabetes, suggesting a role in the development of type 2 diabetes. Furthermore, epidemiological studies suggest a link between vitamin D deficiency in early life and the later onset of type 1 diabetes. In some populations, type 1 diabetes is associated with certain polymorphisms within the vitamin D receptor gene. In studies in nonobese diabetic mice, pharmacological doses of 1alpha,25-dihydroxyvitamin D3, or its structural analogues, have been shown to delay the onset of diabetes, mainly through immune modulation. Vitamin D deficiency may, therefore, be involved in the pathogenesis of both forms of diabetes, and a better understanding of the mechanisms involved could lead to the development of preventive strategies.

Ultraviolet radiation and autoimmune disease: insights from epidemiological research

This review examines the epidemiological evidence that suggests ultraviolet radiation (UVR) may play a protective role in three autoimmune diseases: multiple sclerosis, insulin-dependent diabetes mellitus and rheumatoid arthritis. To date, most of the information has accumulated from population studies that have studied the relationship between geography or climate and autoimmune disease prevalence. An interesting gradient of increasing prevalence with increasing latitude has been observed for at least two of the three diseases. This is most evident for multiple sclerosis, but a similar gradient has been shown for insulin-dependent diabetes mellitus in Europe and North America. Seasonal influences on both disease incidence and clinical course and, more recently, analytical studies at the individual level have provided further support for a possible protective role for UVR in some of these diseases but the data are not conclusive. Organ-specific autoimmune diseases involve Th1 cell-mediated immune processes. Recent work in photoimmunology has shown ultraviolet B (UVB) can specifically attenuate these processes through several mechanisms which we discuss. In particular, the possible contribution of an UVR-induced increase in serum vitamin D (1,25(OH)2D3) levels in the beneficial immunomodulation of these diseases is discussed.

Further evidence for the rising incidence of childhood Type 1 diabetes in Kuwait

AIMS

To provide age-gender standardized incidence rate, temporal trend and seasonal variation of Type 1 diabetes in Kuwaiti children aged < or = 14 years.

METHODS

Data were prospectively collected over a period of 6 years (1992-1997) according to the DiaMond Project protocol using the capture-recapture method of ascertainment.

RESULTS

Data ascertainment varied between 90% and 96%. The incidence rate of Type 1 diabetes was 20.1 per 100,000 children 0-14 years (95% confidence interval (CI) 18.0-22.1); age-standardized incidence rate 20.9 (95% CI 18.8-23.0). The incidence rate among boys, 21.1 per 100,000 (95% CI 18.1-24.1) was slightly higher than that among girls, 19.0 per 100,000 (95% CI 16.1-21.8). The age-standardized incidence rate was 21.9 (95% CI 18.9-24.8) in boys, and 19.9 (95 CI 17.1-22.8) in girls. Incidence rates increased with age in both sexes (boys chi(2) for linear trend = 13.5, P < 0.001; and for girls chi(2) = 27.8, P < 0.0001). There was a significant trend towards increase in overall incidence during the 6-year period (chi(2) = 6.210, P = 0.013), and in age group 5-9 (chi(2) = 10.8, P = 0.001). Seasonality was demonstrated overall, in boys and girls (P < 0.001).

CONCLUSION

The incidence of Type 1 diabetes in Kuwait is high compared with the neighbouring Arab countries, and it appears to be increasing as in many European populations.

Impact of genetic and non-genetic factors in type 1 diabetes

Type 1 insulin-dependent diabetes is due to destruction of the insulin secreting cells of the islets of Langerhans. The disease is caused by non-genetic, probably environmental, factors operating in a genetically susceptible host to initiate a destructive immune process. These unknown environmental factors may operate over a limited period either in early or later and to a variable degree, playing a particularly substantial role in adults. The environment then induces an immune process associated with destruction of the islet beta cell that can be detected in early life and persists up to disease onset. Apart from an association with the insulin gene there is no evidence that genes associated with type 1 diabetes, including HLA and CTLA4 influence the targeting of the immune response to the insulin-secreting cells. The critical period of immune activation is probably short and the process leading to diabetes probably has a long prodrome but of variable duration that determines the age at presentation with clinical disease. The amplification both of this immune response and the destructive process is in part genetically determined, involving HLA genes. The clinical spectrum of the disease process associated with type 1 diabetes is wide, encompassing insulin-dependence, non-insulin dependence and even transient impaired glucose tolerance. Type 1 diabetes presenting in adults, in contrast to children, is predominantly determined by non-genetic factors with a reduced role for protective and susceptibility HLA alleles. Thus, the evidence is that genes involved in genetic susceptibility to type 1 diabetes operate predominantly in children not adults and in both amplify the immune response and the rate of disease progression.

Incidence of type 1 diabetes mellitus diagnosed before age 20 years in Canterbury, New Zealand over the last 30 years

This study examined the epidemiological characteristics of type 1 diabetes mellitus (DM) presenting in Canterbury, New Zealand, between 1970 and 1999. All patients with type 1 DM aged 0-19 years at diagnosis within the Canterbury geographical region were either admitted to the regional hospital or seen acutely as outpatients in clinics at the same institution. Primary ascertainment of incident cases, through notification by the attending physician or paediatrician, began prospectively in 1982. Incident cases between 1970 and 1982 were ascertained retrospectively from clinic and hospital records. For the years 1970-99, there were 474 incident cases (256 males, 218 females). Incidence rates determined from 5-yearly census population denominators ranged from 2.40 to 26.59 patients/100,000 person years. The mean for 5-year periods, starting from 1970, increased from 6.79 to 22.79 patients/100,000 person years, i.e. a 3.4-fold increase over 30 years. The increase in incidence based on linear regression of these data is 0.59 patients/100,000 per year, or an annual increase of 5% derived from regression of the natural logarithms of the incidence data. These observations are consistent with the increasing attack rates for type 1 DM reported worldwide.

Epidemiology of diabetes mellitus in children in Hong Kong: the Hong Kong childhood diabetes register

OBJECTIVES

To establish a registry for Chinese children with onset of type 1 (insulin dependent) diabetes mellitus before 15 years of age and to determine the incidence of childhood onset type 1 diabetes mellitus in Chinese children in Hong Kong.

RESEARCH DESIGN AND METHODS

A registry was established in 1997 to collect childhood diabetes cases retrospectively from all districts in Hong Kong. The study included all newly diagnosed cases of diabetes with onset < 15 yr of age from 1st January 1984 to 31 December 1996. Primary ascertainment was based on review of medical records at all regional public hospitals in Hong Kong and survey of all the registered practitioners in Hong Kong. The secondary source of validation was made impractical, if not impossible, because of the recent implementation of the Personal Data Privacy Ordinance in Hong Kong.

RESULTS

A total of 255 diabetic cases were identified, 227 type 1 diabetes mellitus (218 were Chinese), 18 type 2 diabetes mellitus and 11 secondary diabetes. 246 patients were Chinese and 9 non-Chinese. The age-standardized incidence of type 1 and type 2 diabetes mellitus in southern Chinese children in Hong Kong was 1.4/100,000/yr and 0.1/100,000/yr respectively for children < 15 yr of age during the study period. The incidence rates for type 1 diabetes were 0.9, 1.5 and 1.7 per 100,000/yr for 0-4 years, 5 to 9 years and 10 to 14 years age-groups respectively. The incidence for males was 1.2/100,000/yr and for females 1.7/100,000/yr. A significant increase in the incidence was demonstrated during the study period by simple linear regression (slope 0.14/100,000/year, r2 = 0.73, p = 0.0002)

CONCLUSIONS

A diabetic registry is established in Hong Kong. This study documents a very low incidence rate of childhood type 1 diabetes mellitus in southern Chinese children in Hong Kong and we have seen an increasing incidence of the disease in the past 13 years.

New insights into the epidemiology of type 1 diabetes in Mediterranean countries

In Mediterranean countries, the incidence (per 100,000 per year) of Type 1 diabetes in children aged under 15 years shows wide variation from country to country, ranging from 2.45 in Macedonia to 34.4 in Sardinia. By interacting with environmental factors such as diet, toxins or viral infections, the HLA plus non-HLA genes of susceptibility or resistance to Type 1 diabetes so far identified are the strongest determinants of the disease as far as incidence, age at onset and sex ratio are concerned. The distribution of these genes in the Mediterranean region is still not completely known. Sardinians are the most suitable population for studying such phenomena for three main reasons: their genetic features have been repeatedly analysed in depth; their incidence rate of Type 1 diabetes is by far the highest in the Mediterranean area; and considerable colonies of Sardinian emigrants settled in neighbouring low-incidence Italian regions. Studies on Spaniards and Jews have also contributed to a better understanding of the respective roles of genetic and environmental factors. From a body of research on the Mediterranean populations, it can be concluded that great genetic heterogeneity accounts for the wide variation in incidence of Type 1 diabetes, while rather ubiquitious environmental factors trigger the disease in genetically predisposed individuals.