The incidence of type 2 diabetes mellitus in Taiwan

Changes in insulin resistance, glucose effectiveness, and first and second phases of insulin secretion in women aged 45-60 years old in Taiwan

BACKGROUND

In women after menopause, the incidence of diabetes mellitus increases. Increased insulin resistance (IR), decreased glucose effectiveness (GE), and the first and second phases of insulin secretion (FPIS and SPIS), are the four most important factors that trigger glucose intolerance and diabetes (diabetogenic factor [DF]). In the cross-sectional study, we enrolled nondiabetic women between the ages of 45 and 60 years to observe the changes in DFs during the perimenopausal period and to elucidate the underlying mechanisms of diabetes in menopausal women.

METHODS

We randomly enrolled 4194 women who underwent health checkups. Using demographic and biochemical data, IR, FPIS, SPIS, and GE were calculated using previously published equations. The relationship between the DFs and age was evaluated using a simple correlation.

RESULTS

Body mass index, blood pressure, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, and SPIS were higher, and GE was lower in older women (≥52 years old). A significant decrease in GE and increased SPIS were observed with age. However, no changes were observed in IR or FPIS.

CONCLUSION

The IR and FPIS did not change during perimenopause. Increased SPIS may compensate for the decrease in GE, which is probably one of the reasons for the higher incidence of diabetes in menopausal women.

Comparing Multiple Linear Regression and Machine Learning in Predicting Diabetic Urine Albumin–Creatinine Ratio in a 4-Year Follow-Up Study

The urine albumin–creatinine ratio (uACR) is a warning for the deterioration of renal function in type 2 diabetes (T2D). The early detection of ACR has become an important issue. Multiple linear regression (MLR) has traditionally been used to explore the relationships between risk factors and endpoints. Recently, machine learning (ML) methods have been widely applied in medicine. In the present study, four ML methods were used to predict the uACR in a T2D cohort. We hypothesized that (1) ML outperforms traditional MLR and (2) different ranks of the importance of the risk factors will be obtained. A total of 1147 patients with T2D were followed up for four years. MLR, classification and regression tree, random forest, stochastic gradient boosting, and eXtreme gradient boosting methods were used. Our findings show that the prediction errors of the ML methods are smaller than those of MLR, which indicates that ML is more accurate. The first six most important factors were baseline creatinine level, systolic and diastolic blood pressure, glycated hemoglobin, and fasting plasma glucose. In conclusion, ML might be more accurate in predicting uACR in a T2D cohort than the traditional MLR, and the baseline creatinine level is the most important predictor, which is followed by systolic and diastolic blood pressure, glycated hemoglobin, and fasting plasma glucose in Chinese patients with T2D.

Factors Related to Diabetes Mellitus in the Middle-Aged and Over in Taiwan

Study Objective: to investigate the factors related to diabetes mellitus in the middle-aged and over in Taiwan. Method: data from seven surveys (in 1989–2011) from the “Taiwan Longitudinal Study on Aging” (TLSA), among cohort B (above the age 60 in 1989), cohort A (aged 50–66 in 1996), and cohort C (aged 50–66 in 2003), were analyzed by the interval-censored Cox model. Results: in the early aging stage (aged 60–64), diabetes mellitus prevalence among the same age appeared the lowest in cohort B, followed by cohort A; cohort C reveals the highest than the young generation. Moreover, suffering from hypertension and kidney diseases are closely related to diabetes mellitus, with the diabetes mellitus suffering hazard ratio of 2.53 (95%: 2.35, 2.73) and 1.26 (95%: 1.11, 1.44) times, respectively. For people with fair and poor self-rated health, the risk of suffering from diabetes mellitus is 1.16 (95%: 1.07, 1.27) and 1.50 (95%: 1.35, 1.67) times compared to people with good self-rated health, respectively. Conclusions: in this study, it is considered that an advanced interval censoring model analysis could more accurately grasp the characteristics of factors in people who are middle-aged and over suffering from diabetes mellitus in Taiwan.

Chronic arsenic exposure impairs adaptive thermogenesis in male C57BL/6J mice

The global prevalence of type 2 diabetes (T2D) has doubled since 1980. Human epidemiological studies support arsenic exposure as a risk factor for T2D, although the precise mechanism is unclear. We hypothesized that chronic arsenic ingestion alters glucose homeostasis by impairing adaptive thermogenesis, i.e., body heat production in cold environments. Arsenic is a pervasive environmental contaminant, with more than 200 million people worldwide currently exposed to arsenic-contaminated drinking water. Male C57BL/6J mice exposed to sodium arsenite in drinking water at 300 μg/L for 9 wk experienced significantly decreased metabolic heat production when acclimated to chronic cold tolerance testing, as evidenced by indirect calorimetry, despite no change in physical activity. Arsenic exposure increased total fat mass and subcutaneous inguinal white adipose tissue (iWAT) mass. RNA sequencing analysis of iWAT indicated that arsenic dysregulated mitochondrial processes, including fatty acid metabolism. Western blotting in WAT confirmed that arsenic significantly decreased TOMM20, a correlate of mitochondrial abundance; PGC1A, a master regulator of mitochondrial biogenesis; and, CPT1B, the rate-limiting step of fatty acid oxidation (FAO). Our findings show that chronic arsenic exposure impacts the mitochondrial proteins of thermogenic tissues involved in energy expenditure and substrate regulation, providing novel mechanistic evidence for arsenic's role in T2D development.

The roles of first phase, second phase insulin secretion, insulin resistance, and glucose effectiveness of having prediabetes in nonobese old Chinese women

It has been established that prediabetes can causes significant comorbidities, particularly in the elderly. The deterioration of glucose metabolism are generally considered to be results of the impairment of the 4 factors: first, second insulin secretion (FPIS, SPIS, respectively), glucose effectiveness (GE), and insulin resistance. In this study, we enrolled older women to investigate their relationships with prediabetes.Five thousand four hundred eighty-two nonobese, nondiabetic women were included. They were divided into normal glucose tolerance and prediabetes groups. Receiver operating characteristic curve was performed to investigate the effects on whether to have prediabetes for each factors. Two models were built: Model 1: FPIS + SPIS, and Model 2: model 1 + GE. The area under the receiver operating characteristic (aROC) curve was used to determine the predictive power of these models.The aROC curve of GE was significantly higher than the diagonal line followed by SPIS and FPIS accordingly. The aROC curve of Model 1 (0.611) was not different from GE. However, Model 2 improved significantly up to 0.663. Based on this model, an equation was built (-0.003 × GE - 212.6 × SPIS - 17.9 × insulin resistance + 4.8). If the calculated value is equal or higher than 0 (≥0), then the subject has higher chance to have prediabetes (sensitivity = 0.607, specificity = 0.635).Among the 4 factors, GE is the most important contributor for prediabetes in older women. By building a model composed of FPIS, SPIS, and GE, the aROC curve increased significantly. The equation built from this model could predict prediabetes precisely.

Arsenic and human health effects: A review

Arsenic (As) is ubiquitous in nature and humans being exposed to arsenic via atmospheric air, ground water and food sources are certain. Major sources of arsenic contamination could be either through geological or via anthropogenic activities. In physiological individuals, organ system is described as group of organs that transact collectively and associate with other systems for conventional body functions. Arsenic has been associated with persuading a variety of complications in body organ systems: integumentary, nervous, respiratory, cardiovascular, hematopoietic, immune, endocrine, hepatic, renal, reproductive system and development. In this review, we outline the effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions. Additionally, underlying mechanisms of disease development in each organ system due to arsenic have also been explored. Strikingly, arsenic has been able to induce epigenetic changes (in utero) and genetic mutations (a leading cause of cancer) in the body. Occurrence of various arsenic induced health effects involving emerging areas such as epigenetics and cancer along with their respective mechanisms are also briefly discussed.

An updated review on cancer risk associated with incretin mimetics and enhancers

Incretin-based therapies, including the use of incretin mimetics of glucagon-like peptide-1 receptor (GLP-1R) agonists and incretin enhancers of dipeptidyl-peptidase 4 (DPP-4) inhibitors, are widely used by clinicians for glucose lowering in patients with type 2 diabetes mellitus. These agents have benefits of a lower risk of hypoglycemia, being neutral for body weight for DPP-4 inhibitors and having a potential for weight reduction with GLP-1R agonists. They may also have a neutral or beneficial cardiovascular effect. Despite these benefits, an increased risk of cancer (especially pancreatic cancer and thyroid cancer) associated with incretin-based therapies has been reported. In this article, we reviewed related literature of experimental animal and observational human studies, clinical trials, and meta-analyses published until December 15, 2014. Current studies suggested a probable role of GLP-1R activation on the development of pancreatic cancer and thyroid cancer in rodents, but such an effect in humans is not remarkable due to the lower or lack of expression of GLP-1R on human pancreatic ductal cells and thyroid tissues. Findings in human studies are controversial and inconclusive. In the analyses of the US Food and Drug Administration adverse events reporting system, a significantly higher risk of pancreatic cancer was observed for GLP-1R agonists and DPP-4 inhibitors, but a significantly higher risk of thyroid cancer was only observed for GLP-1R agonists. Such a higher risk of pancreatic cancer or thyroid cancer could not be similarly demonstrated in other human observational studies or analyses of data from clinical trials. With regards to cancers other than pancreatic cancer and thyroid cancer, available studies supported a neutral association in humans. Some preliminary studies even suggested a potentially beneficial effect on the development of other cancers with the use of incretins. Based on current evidence, continuous monitoring of the cancer issues related to incretin-based therapies is required, even though the benefits may outweigh the potential cancer risk in the general patients with type 2 diabetes mellitus.

Prolonged environmental exposure of arsenic through drinking water on the risk of hypertension and type 2 diabetes

Prolonged exposure to inorganic arsenic has been a severe environmental public health issue worldwide in the recent decades. Increasing evidence has suggested a possible role of prolonged arsenic exposure through drinking water in the development of arsenic-induced chronic noncancer diseases, among which hypertension and type 2 diabetes (T2D) are the focus of concern. Although exposure to high levels of arsenic has been reported to be associated with excess risk of hypertension or T2D in a dose-dependent manner, the association has yet to be established, especially low-level exposure. This cross-sectional study was designed to evaluate the potential association between prolonged environmental arsenic exposure through drinking water and the prevalence of hypertension and T2D in Inner Mongolia, China, with emphasis on the assessment of low-level exposure. In this study (a total of 669 men and women), we found that the blood pressure levels were significantly correlated with cumulative arsenic exposure and that the systolic blood pressure of the subjects with arsenic exposure>50 μg/L was significantly higher than those of the subjects with <10 and 10-50 μg/L exposure. Significant prevalence of hypertension was found in the subjects of the >50 μg/L group both before and after adjustment for confounders. In addition, a significant negative relationship was found between urinary arsenic percentage of dimethylated arsenic (DMA%) and the prevalence of hypertension in the >50 μg/L group. However, low-level arsenic exposure (10-50 μg/L) was not statistically associated with hypertension. No significant difference of blood glucose was found among the groups with different arsenic exposure levels. No statistical association was found between arsenic exposure and T2D. Our findings suggested that prolonged arsenic exposure might play a role in the development of hypertension; however, only high-level arsenic was associated with the risk of hypertension. Our findings also indicated that lower DMA% might be related with the increased susceptibility of arsenic-induced hypertension.

Arsenic induced neuronal apoptosis in guinea pigs is Ca2+ dependent and abrogated by chelation therapy: role of voltage gated calcium channels

Arsenic contaminated drinking water has affected more than 200 million people globally. Chronic arsenicism has also been associated with numerous neurological diseases. One of the prime mechanisms postulated for arsenic toxicity is reactive oxygen species (ROS) mediated oxidative stress. In this study, we explored the kinetic relationship of ROS with calcium and attempted to dissect the calcium ion channels responsible for calcium imbalance after arsenic exposure. We also explored if mono- or combinational chelation therapy prevents arsenic-induced (25ppm in drinking water for 4 months) neuronal apoptosis in a guinea pig animal model. Results indicate that chronic arsenic exposure caused a significant increase in ROS followed by NO and calcium influx. This calcium influx is mainly dependent on L-type voltage gated channels that disrupt mitochondrial membrane potential, increase bax/bcl2 levels and caspase 3 activity leading to apoptosis. Interestingly, blocking of ROS could completely reduce calcium influx whereas calcium blockage partially reduced ROS increase. While in general mono- and combinational chelation therapies were effective in reversing arsenic induced alteration, combinational therapy of DMSA and MiADMSA was most effective. Our results provide evidence for the role of L-type calcium channels in regulating arsenic-induced calcium influx and DMSA+MiADMSA combinational therapy may be a better protocol than monotherapy in mitigating chronic arsenicosis.

Evaluation of the association between arsenic and diabetes: a National Toxicology Program workshop review

BACKGROUND

Diabetes affects an estimated 346 million persons globally, and total deaths from diabetes are projected to increase > 50% in the next decade. Understanding the role of environmental chemicals in the development or progression of diabetes is an emerging issue in environmental health. In 2011, the National Toxicology Program (NTP) organized a workshop to assess the literature for evidence of associations between certain chemicals, including inorganic arsenic, and diabetes and/or obesity to help develop a focused research agenda. This review is derived from discussions at that workshop.

OBJECTIVES

Our objectives were to assess the consistency, strength/weaknesses, and biological plausibility of findings in the scientific literature regarding arsenic and diabetes and to identify data gaps and areas for future evaluation or research. The extent of the existing literature was insufficient to consider obesity as an outcome.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

Studies related to arsenic and diabetes or obesity were identified through PubMed and supplemented with relevant studies identified by reviewing the reference lists in the primary literature or review articles.

CONCLUSIONS

Existing human data provide limited to sufficient support for an association between arsenic and diabetes in populations with relatively high exposure levels (≥ 150 µg arsenic/L in drinking water). The evidence is insufficient to conclude that arsenic is associated with diabetes in lower exposure (< 150 µg arsenic/L drinking water), although recent studies with better measures of outcome and exposure support an association. The animal literature as a whole was inconclusive; however, studies using better measures of diabetes-relevant end points support a link between arsenic and diabetes.

Role of environmental chemicals in diabetes and obesity: a National Toxicology Program workshop review

BACKGROUND

There has been increasing interest in the concept that exposures to environmental chemicals may be contributing factors to the epidemics of diabetes and obesity. On 11-13 January 2011, the National Institute of Environmental Health Sciences (NIEHS) Division of the National Toxicology Program (NTP) organized a workshop to evaluate the current state of the science on these topics of increasing public health concern.

OBJECTIVE

The main objective of the workshop was to develop recommendations for a research agenda after completing a critical analysis of the literature for humans and experimental animals exposed to certain environmental chemicals. The environmental exposures considered at the workshop were arsenic, persistent organic pollutants, maternal smoking/nicotine, organotins, phthalates, bisphenol A, and pesticides. High-throughput screening data from Toxicology in the 21st Century (Tox21) were also considered as a way to evaluate potential cellular pathways and generate -hypotheses for testing which and how certain chemicals might perturb biological processes related to diabetes and obesity.

CONCLUSIONS

Overall, the review of the existing literature identified linkages between several of the environmental exposures and type 2 diabetes. There was also support for the "developmental obesogen" hypothesis, which suggests that chemical exposures may increase the risk of obesity by altering the differentiation of adipocytes or the development of neural circuits that regulate feeding behavior. The effects may be most apparent when the developmental exposure is combined with consumption of a high-calorie, high-carbohydrate, or high-fat diet later in life. Research on environmental chemical exposures and type 1 diabetes was very limited. This lack of research was considered a critical data gap. In this workshop review, we outline the major themes that emerged from the workshop and discuss activities that NIEHS/NTP is undertaking to address research recommendations. This review also serves as an introduction to an upcoming series of articles that review the literature regarding specific exposures and outcomes in more detail.

Arsenic and diabetes: current perspectives

Arsenic is a naturally occurring toxic metalloid of global concern. Many studies have indicated a dose-response relationship between accumulative arsenic exposure and the prevalence of diabetes mellitus (DM) in arseniasis-endemic areas in Taiwan and Bangladesh, where arsenic exposure occurs through drinking water. Epidemiological researches have suggested that the characteristics of arsenic-induced DM observed in arseniasis-endemic areas in Taiwan and Mexico are similar to those of non-insulin-dependent DM (Type 2 DM). These studies analyzed the association between high and chronic exposure to inorganic arsenic in drinking water and the development of DM, but the effect of exposure to low to moderate levels of inorganic arsenic on the risk of DM is unclear. Navas-Acien et al. recently proposed that a positive association existed between total urine arsenic and the prevalence of Type 2 DM in people exposed to low to moderate levels of arsenic. However, the diabetogenic role played by arsenic is still debated upon. An increase in the prevalence of DM has been observed among residents of highly arsenic-contaminated areas, whereas the findings from community-based and occupational studies in low-arsenic-exposure areas have been inconsistent. Recently, a population-based cross-sectional study showed that the current findings did not support an association between arsenic exposure from drinking water at levels less than 300 μg/L and a significantly increased risk of DM. Moreover, although the precise mechanisms for the arsenic-induced diabetogenic effect are still largely undefined, recent in vitro experimental studies indicated that inorganic arsenic or its metabolites impair insulin-dependent glucose uptake or glucose-stimulated insulin secretion. Nevertheless, the dose, the form of arsenic used, and the experimental duration in the in vivo studies varied greatly, leading to conflicting results and ambiguous interpretation of these data with respect to human exposure to arsenic in the environment. Moreover, the experimental studies were limited to the use of arsenic concentrations much higher than those relevant to human exposure. Further prospective epidemiological studies might help to clarify this controversy. The issues about environmental exposure assessment and appropriate biomarkers should also be considered. Here, we focus on the review of mechanism studies and discuss the currently available evidence and conditions for the association between environmental arsenic exposure and the development of DM.

Diabetes-related change in physical disability from midlife to older adulthood: evidence from 1996-2003 Survey of Health and Living Status of the Elderly in Taiwan

One in five older adults in Taiwan have been diagnosed with diabetes. This study drew on disability data for 5121 nationally representative middle-aged and older adults from the 1996-2003 Survey of Health and Living Status of the Elderly in Taiwan (SHLSET). By employing cohort sequential design and multilevel models, it combined cross-sectional and longitudinal evidence to characterize the age trajectory of physical disability from midlife to older adulthood and to discern the extent to which diabetes contributes to the variation in that trajectory. The main effects of diabetes and diabetes × age interaction in the fully controlled model provide evidence that diabetes independently and consistently changes physical functioning over and above natural aging processes in Taiwanese adults. In addition, while adding diabetes in the age trajectory of physical disability explained 3.2% and 1.6% of the variance in levels of and linear changes in physical disability trajectory, respectively, further adding follow-up status, sociodemographic factors and comorbidities altogether explained 40.5% and 29.1% of the variance in levels of and linear changes in that trajectory. These results imply that preventing the incidence of diabetes-related comorbidities may reduce the deterioration in both levels of and rates of change in physical disability.

Sex differences in the incidence of hemorrhagic and ischemic stroke among diabetics in Taiwan

BACKGROUND

Diabetes mellitus is an important risk factor for stroke, but whether there is differential gender-specific risk has not been fully elucidated. We aimed to explore the impact of gender on incidence and relative risks of hemorrhagic and ischemic stroke among the diabetic population in Taiwan.

METHODS

In this study, 500,868 diabetic patients and 500,248 age matched and-sex-matched nondiabetic individuals were linked to inpatient claims (1997-2002) to identify hospitalizations for nontraumatic hemorrhagic and ischemic stroke. Incidence density was calculated with the Poisson assumption, and Kaplan-Meier analysis was used to assess the cumulative incidence over a 6-year follow-up period. We also evaluated the relative hazards of stroke in relation to diabetes with the Cox proportional hazard model, adjusted with demographics and geographic regions.

RESULTS

The incidence of hemorrhagic stroke in diabetic women was less than that in diabetic men except in those aged > or =85, but the difference between male and female diabetic patients was less pronounced with ischemic stroke. The hazard ratios (HRs) of hemorrhagic and ischemic stroke among diabetic women were increased by a magnitude of 1.2 and 1.32, respectively, which were significantly higher than those of diabetic men. Further age-stratified analysis indicated that young and middle-aged diabetic women tended to have higher HRs and that diabetic women aged <35 suffered from particularly high HRs (HR 7.69, 95% confidence interval [CI] 1.81-32.75 for hemorrhagic stroke, and HR = 8.46, 95% CI 4.28-16.75 for ischemic stroke).

CONCLUSIONS

There was a significant gender-diabetes interactive effect on the incidence of hemorrhagic and ischemic stroke. Additionally, young Taiwanese diabetic patients were most vulnerable to an increased relative risk of hemorrhagic and ischemic stroke. Comprehensive diabetic care with stroke prevention measures should be emphasized in young diabetic people in order to prevent premature disability.

Inorganic arsenic exposure and its relation to metabolic syndrome in an industrial area of Taiwan

Past arsenic exposure was found associated with increased incidence of type 2 diabetes. However, the mechanisms remain unclear. Metabolic syndrome has been shown as a strong predictor for diabetes occurrence. We aimed at examining the association of inorganic arsenic exposure and the prevalence of metabolic syndrome. The authors recruited 660 age and gender stratified random population of residents in central Taiwan during 2002-2003. They received home interviews and health examinations at local health care units, where blood and hair specimens were collected. Hair arsenic (H-As) concentrations were determined by inductively coupled plasma-mass spectrometry. Metabolic syndrome was defined as the presence of three or more of the following risk factors: elevated levels of blood pressure, plasma glucose, and triglycerides, also the body mass index, and reduced high-density lipoprotein. Prevalence of metabolic syndrome increased from the 2nd tertile (0.034 ug/g) of H-As levels (odds ratio=2.54, 95% confidence interval: 1.20-5.39, p=0.015) after the adjustment for age, gender, occupation and life styles including cigarette smoking. We further found linear relation between H-As concentrations and increased levels of plasma glucose and lipids, and blood pressures. This first report may help identify modifiable factors associated with diabetogenesis and cardiovascular disease progression and thus be worth following for community health.

Increased hexokinase II expression in the renal glomerulus of mice in response to arsenic

Epidemiological studies link arsenic exposure to increased risks of cancers of the skin, kidney, lung, bladder and liver. Additionally, a variety of non-cancerous conditions such as diabetes mellitus, hypertension, and cardiovascular disease have been associated with chronic ingestion of low levels of arsenic. However, the biological and molecular mechanisms by which arsenic exerts its effects remain elusive. Here we report increased renal hexokinase II (HKII) expression in response to arsenic exposure both in vivo and in vitro. In our model, HKII was up-regulated in the renal glomeruli of mice exposed to low levels of arsenic (10 ppb or 50 ppb) via their drinking water for up to 21 days. Additionally, a similar effect was observed in cultured renal mesangial cells exposed to arsenic. This correlation between our in vivo and in vitro data provides further evidence for a direct link between altered renal HKII expression and arsenic exposure. Thus, our data suggest that alterations in renal HKII expression may be involved in arsenic-induced pathological conditions involving the kidney. More importantly, these results were obtained using environmentally relevant arsenic concentrations.

Predictors of incident diabetes, metabolic syndrome in middle-aged adults: a 10-year follow-up study from Kinmen, Taiwan

AIMS/HYPOTHESIS

The aim of this prospective study was to assess a population-based cohort for the predictors of incident diabetes and metabolic syndrome, which is most likely to lead to cardiovascular disease.

METHODS

We compared the baseline individual components of metabolic syndrome, adopted from the NCEP ATP III for Asians, in 3629 subjects who developed diabetes, metabolic syndrome, or diabetes and metabolic syndrome to those who remained free of diabetes and metabolic syndrome for 10 years.

RESULTS

The incidence rate of diabetes was 7.8% (9.8% in men and 6.3% in women, respectively), and metabolic syndrome was 24.2% (23.4% in men and 24.7% women, respectively). Eighty-five men and 99 women developed diabetes and metabolic syndrome, which yielded incidence rates of 5.7% in men and 4.7% in women. After adjustment for related covariable factors, each component of metabolic syndrome in women, higher triglyceride and greater waist circumference in men, independently predicted future incident diabetes and metabolic syndrome as compared with those who remained free of diabetes and metabolic syndrome.

CONCLUSIONS/INTERPRETATION

These findings suggest that several components of metabolic syndrome independently precede the development of diabetes and metabolic syndrome. Further intervention studies are required to demonstrate the benefits of intervention with all aspects in decreasing the incidence of diabetes and metabolic syndrome in the general population.

Development and validation of the Chinese version of the Diabetes Management Self-efficacy Scale

OBJECTIVE

The purpose of this study was to translate the Diabetes Management Self-Efficacy Scale (DMSES) into Chinese and test the validity and reliability of the instrument within a Taiwanese population.

RESEARCH DESIGN AND METHODS

A two-stage design was used for this study. Stage I consisted of a multi-stepped process of forward and backward translation, using focus groups and consensus meetings to translate the 20-item Australia/English version DMSES to Chinese and test content validity. Stage II established the psychometric properties of the Chinese version DMSES (C-DMSES) by examining the criterion, convergent and construct validity, internal consistency and stability testing. The sample for Stage II comprised 230 patients with type 2 diabetes aged 30 years or more from a diabetes outpatient clinic in Taiwan.

RESULTS

Three items were modified to better reflect Chinese practice. The C-DMSES obtained a total average CVI score of .86. The convergent validity of the C-DMSES correlated well with the validated measure of the General Self-Efficacy Scale in measuring self-efficacy (r=.55; p<.01). Criterion-related validity showed that the C-DMSES was a significant predictor of the Summary of Diabetes Self-Care Activities scores (Beta=.58; t=10.75, p<.01). Factor analysis supported the C-DMSES being composed of four subscales. Good internal consistency (Cronbach's alpha=.77 to .93) and test-retest reliability (Pearson correlation coefficient r=.86, p<.01) were found.

CONCLUSIONS

The C-DMSES is a brief and psychometrically sound measure for evaluation of self-efficacy towards management of diabetes by persons with type 2 diabetes in Chinese populations.

Increasing incidence of diagnosed type 2 diabetes in Taiwan: analysis of data from a national cohort

AIMS/HYPOTHESIS

Epidemiological evidence shows an increasing prevalence of type 2 diabetes in Taiwan. The aim of this study was to assess the yearly incidence for this country during 1992-1996.

SUBJECTS AND METHODS

Data obtained by telephone interviews of 93,484 diagnosed diabetic patients enrolled in Taiwan's National Health Insurance programme formed the basis of this study. A total of 36,153 incident cases of type 2 diabetes (17,097 men and 19,056 women) were identified and incidence rates calculated. The trends of obesity and parental diabetes were also evaluated.

RESULTS

The overall 5-year incidences for men and women were 187.1 and 218.4 per 100,000 population, respectively. The trends from 1992-1996 were increased for all age groups in men and for most age groups in women. A 2.8-fold increase in incidence was observed for the youngest age group (<35 years), in which the increase in incidence was higher than in the older age groups. Men showed a higher fold increase in incidence than did women (3.5 vs 2.1). Obesity at interview increased from 39.2% in 1992 to 47.6% in 1996 (p<0.001) and was significant for all ages. Parental diabetes showed no yearly change when all patients were analysed together, but there was a trend towards a decrease in the youngest age group (<35 years) and a trend towards an increase in the oldest age groups (>/=55 years).

CONCLUSIONS/INTERPRETATION

An increasing incidence of diagnosed type 2 diabetes was observed for each sex in most age groups in Taiwan, but was most marked in the youngest age group. A parallel increase in obesity was observed with the increasing incidence of diabetes.

Sodium arsenite impairs insulin secretion and transcription in pancreatic beta-cells

Human studies have shown that chronic inorganic arsenic (iAs) exposure is associated with a high prevalence and incidence of type 2 diabetes. However, the mechanism(s) underlying this effect are not well understood, and practically, there is no information available on the effects of arsenic on pancreatic beta-cells functions. Thus, since insulin secreted by the pancreas plays a crucial role in maintaining glucose homeostasis, our aim was to determine if sodium arsenite impairs insulin secretion and mRNA expression in single adult rat pancreatic beta-cells. Cells were treated with 0.5, 1, 2, 5 and 10 microM sodium arsenite and incubated for 72 and 144 h. The highest dose tested (10 microM) decreased beta-cell viability, by 33% and 83%, respectively. Insulin secretion and mRNA expression were evaluated in the presence of 1 and 5 microM sodium arsenite. Basal insulin secretion, in 5.6 mM glucose, was not significantly affected by 1 or 5 microM treatment for 72 h, but basal secretion was reduced when cells were exposed to 5 microM sodium arsenite for 144 h. On the other hand, insulin secretion in response to 15.6 mM glucose decreased with sodium arsenite in a dose-dependent manner in such a way that cells were no longer able to distinguish between different glucose concentrations. We also showed a significant decrease in insulin mRNA expression of cells exposed to 5 microM sodium arsenite during 72 h. Our data suggest that arsenic may contribute to the development of diabetes mellitus by impairing pancreatic beta-cell functions, particularly insulin synthesis and secretion.

Blackfoot disease and arsenic: a never-ending story

Blackfoot disease (BFD) is an endemic peripheral vascular disease confined to the southwestern coast of Taiwan. This article reviews the epidemiology, clinical manifestations and diagnosis, pathology, etiology and pathogenesis of this disease. Sporadic cases of BFD occurred as early as in the early 20th century, and peak incidence was noted between 1956 and 1960, with prevalence rates ranging from 6.51 to 18.85 per 1,000 population in different villages. Typical clinical symptoms and signs of progressive arterial occlusion mainly found in the lower extremities, but in rare cases, the upper extremities might also be involved. Ulceration, gangrene and spontaneous or surgical amputation were typical fate. An extensive pathological study concluded that 30% of the BFD patients had histologic lesions compatible with thromboangiitis obliterans and 70% showed changes of arteriosclerosis obliterans. Epidemiologic studies carried out since mid-20th century revealed that BFD was associated with the consumption of inorganic arsenic from the artesian wells. Recent studies confirmed the existence of preclinical peripheral vascular disease, subclinical arterial insufficiency and defects in cutaneous microcirculation in the residents of the endemic villages. A more recent study suggested that the methylation capacity of arsenic can interact with arsenic exposure in the development of peripheral vascular disease among residents of BFD-endemic areas. The incidence of BFD decreased dramatically after the implementation of tap water in these villages over the past 2-3 decades. The atherogenicity of arsenic could be associated with its effects of hypercoagulability, endothelial injury, smooth muscle cell proliferation, somatic mutation, oxidative stress, and apoptosis. However, its interaction with some trace elements and its association with hypertension and diabetes mellitus could also explain part of its higher risk of developing atherosclerosis. Although humic substances have also been suggested as a possible cause of BFD, epidemiologic studies are required to confirm its etiologic role.

Oxidative mechanism of arsenic toxicity and carcinogenesis

Arsenic is a known toxin and carcinogen that is present in industrial settings and in the environment. The mechanisms of disease initiation and progression are not fully understood. In the last a few years, there has been increasing evidence of the correlation between the generation of reactive oxygen species (ROS), DNA damage, tumor promotion, and arsenic exposure. This article summarizes the current literature on the arsenic mediated generation of ROS and reactive nitrogen species (RNS) in various biological systems. This article also discusses the role of ROS and RNS in arsenic-induced DNA damage and activation of oxidative sensitive gene expression.

Independent association of uric acid levels with peripheral arterial disease in Taiwanese patients with Type 2 diabetes

AIMS

Hyperuricaemia may be a risk factor for atherosclerotic disease. Its association with peripheral arterial disease (PAD) has not been studied in Taiwanese patients with Type 2 diabetes.

METHODS

Uric acid (UA) levels and PAD were evaluated in 508 Taiwanese outpatients with Type 2 diabetes (210 men, 298 women; mean age +/- sd, 63.8 +/- 10.6 years). PAD was diagnosed when the ankle-brachial index was < 0.9. Patients with an ankle-brachial index of > or = 1.3 were excluded because of possible medial arterial calcification. Potential confounding variables with P < 0.10 were adjusted for in multivariate analyses.

RESULTS

In univariate analyses, UA levels were higher in patients with PAD than in those without PAD (345.0 +/- 95.2 vs. 309.3 +/- 89.2 micromol/l; P < 0.0005). Prevalences of PAD for quintiles of UA levels were 6.8, 8.9, 10.2, 13.1 and 16.5%, respectively (P-trend < 0.05). With UA level as a continuous variable, the multivariate-adjusted odds ratio (95% confidence interval) for PAD was 1.005 (1.001-1.008) (P < 0.01). The optimal cut-off point for UA as determined by the receiver operating characteristic curve was 264.7 micromol/l. The sensitivity and specificity at this cut-off point was 82.6 and 33.3%, respectively. The area under curve was 0.60 (95% confidence interval: 0.53-0.68). The multivariate-adjusted odds ratio for PAD for UA above this level was 2.736 (1.239-6.043) (P < 0.05). The results after excluding 56 cases using diuretics were similar.

CONCLUSIONS

Elevated uric acid level is a significant and independent risk factor for PAD in Taiwanese patients with Type 2 diabetes.

Body mass index and obesity-related metabolic disorders in Taiwanese and US whites and blacks: implications for definitions of overweight and obesity for Asians

BACKGROUND

Recommendations based on scanty data have been made to lower the body mass index (BMI; in kg/m(2)) cutoff for obesity in Asians.

OBJECTIVE

The goal was to compare relations between BMI and metabolic comorbidity among Asians and US whites and blacks.

METHODS

We compared the prevalence rate, sensitivity, specificity, predictive values, and impact fraction of comorbidities at each BMI level and the BMI-comorbidity relations across ethnic groups by using data from the third National Health and Nutrition Examination Survey and the Nutrition and Health Survey in Taiwan (1993-1996).

RESULTS

For most BMI values, the prevalences of hypertension, diabetes, and hyperuricemia were higher for Taiwanese than for US whites. In addition, increments of BMI corresponded to higher odds ratios in Taiwanese than in US whites for hypertriglyceridemia (P = 0.01) and hypertension (P = 0.075). BMI-comorbidity relations were stronger in Taiwanese than in US blacks for all comorbidities studied. BMIs of 22.5, 26, and 27.5 were the cutoffs with the highest sum of positive and negative predictive value for Taiwanese, US white, and US black men, respectively. The same order was observed for women. For BMIs >27, >85% of Taiwanese, 66% of whites, and 55% of blacks had at least one of the studied comorbidities. However, a cutoff close to the median of the studied population was often found by maximizing sensitivity and specificity. Reducing BMI from >25 to <25 in persons in the United States could eliminate 13% of the obesity comorbidity studied. The corresponding cutoff in Taiwan is slightly <24.

CONCLUSION

These data suggest a possible need to set lower BMI cutoffs for Asians, but where to draw the line is a complex issue.

Prevalence and risk factors of peripheral arterial obstructive disease in Taiwanese type 2 diabetic patients

The aim of this study was to evaluate the prevalence and risk factors of peripheral arterial obstructive disease (PAD) in Taiwanese type 2 diabetic patients. A total of 610 patients (268 men and 342 women), aged 63.3 +/- 10.8 years, were recruited from a diabetic clinic in a teaching hospital. PAD was diagnosed by an ankle-brachial index (ABI) < 0.9 on either leg. Risk factors studied were age, sex, body mass index (BMI), smoking, diabetes duration, hypertension, insulin therapy, systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose (FPG), serum total cholesterol (TC), and triglyceride (TG). Overall prevalence of PAD was 10.0% without significant sexual difference. Univariate analyses disclosed age, BMI (inverse association), diabetes duration, hypertension, insulin therapy, and SBP as significant risk factors. In stepwise logistic regression, age, SBP, BMI, and insulin therapy were independent risk factors with respective odds ratios (95% confidence intervals, CI) of 1.09 (1.05-1.13), 1.02 (1.01-1.04), 0.88 (0.80-0.96), and 3.37 (1.83-6.19). In conclusion, prevalence of PAD in Taiwanese type 2 diabetic patients was 10.0% and the major risk factors were older age, lower BMI, higher SBP, and insulin therapy. The inverse association between PAD and BMI is contradictory to the general impression that obesity is a risk factor for PAD.

An overview on peripheral vascular disease in blackfoot disease-hyperendemic villages in Taiwan

The arsenic-related peripheral vascular disease found to be endemic along the southwestern coast of Taiwan is reviewed. In the early 20th century a strange disease involving the lower extremities characterized by typical clinical symptoms and signs of progressive arterial occlusion was reported in a confined area located along the southwestern coast of Taiwan. The disease was locally called "blackfoot disease" because of its gangrenous appearance involving the feet of the patients. The prevalence of this disease ranged from 6.51 to 18.85 per 1,000 population in different villages. Epidemiologic studies revealed that blackfoot disease was associated with the consumption of artesian well water containing high levels of arsenic. High co-occurrence of blackfoot disease and arsenic-related skin lesions such as hyperpigmentation, hyperkeratosis, and skin cancer was also observed. Recent studies also confirmed the association of preclinical peripheral vascular disease with arsenic exposure in a dose-response pattern. Subclinical arterial insufficiency and defects in cutaneous microcirculation can also be demonstrated in seemingly normal subjects living in the endemic villages. The incidence of clinical manifestation of blackfoot disease decreased dramatically after the implementation of tap water in these villages over the past 2-3 decades. The atherogenicity of arsenic could be associated with its effects on hypercoagulability, endothelial injury, smooth muscle cell proliferation, somatic mutation, oxidative stress, and apoptosis. However, its interaction with some trace elements and its association with hypertension and diabetes mellitus could also explain part of its higher risk of developing atherosclerosis.

Epidemiologic evidence of diabetogenic effect of arsenic

It is well documented that arsenic can lead to skin lesions, atherosclerotic diseases and cancers. The association between arsenic exposure and diabetes mellitus is a relatively new finding. Up to now, there are six epidemiologic reports linking diabetes mellitus with arsenic exposure from environmental and occupational sources. Two reports in Taiwan carried out in the blackfoot disease-hyperendemic villages, one cross-sectional and one prospective follow-up of the same cohort, indicate that arsenic exposure from drinking artesian well water is associated with prevalence and incidence of diabetes mellitus in a dose-responsive pattern. The observation of the relation between arsenic exposure and diabetes mellitus is further supported by studies carried out in Sweden and Bangladesh. In Sweden, case-control analyses of death records of copper smelters and glass workers revealed a trend of increasing diabetes mellitus with increasing arsenic exposure from inhalation. In Bangladesh, prevalence of diabetes mellitus among arsenic-exposed subjects with keratosis was about five times higher than unexposed subjects. Increasing trends of diabetes mellitus with indices of arsenic exposure in drinking water seems to be independent of the presence of skin lesions associated with arsenic exposure. Although these studies consistently show an association between arsenic exposure and diabetes mellitus, the weak study designs of cross-sectional or case-control, the use of glucosuria or diabetes death as diagnostic criteria and the lack of adjustment for possible confounders in some studies, are major limitations that may reduce the strength of the evidence.

A review of rosiglitazone in type 2 diabetes mellitus

The thiazolidinedione rosiglitazone maleate works primarily to improve insulin sensitivity in muscle and adipose tissue. It may have additional pharmacologic effects, however, as its main target is peroxisome proliferator-activated receptor-gamma. Data using the homeostasis model assessment and proinsulin:insulin ratio in patients with type 2 diabetes mellitus suggest that rosiglitazone may have the potential to sustain or improve beta-cell function. In these patients the drug reduces fasting plasma glucose, glycosylated hemoglobin, insulin, and C-peptide. In clinical trials, rosiglitazone monotherapy significantly reduced glycosylated hemoglobin by 1.5% compared with placebo and led to significant improvements in glycemic control when given in combination with metformin, sulfonylureas, or insulin. A dosage of 4 mg twice/day significantly reduced fasting plasma glucose levels and produced comparable reductions in glycosylated hemoglobin compared with glyburide. Rosiglitazone has a low risk of gastrointestinal side effects and hypoglycemia, reduced insulin demand, potential sparing effects on beta-cells, and favorable drug interaction profile. Adverse events of clinical significance are edema, anemia, and weight gain. Premarketing data indicate no significant difference in liver enzyme elevations for rosiglitazone, placebo, or active controls. Another drug in the thiazolidinedione class, troglitazone, was associated with idiosyncratic hepatotoxicity and was removed from the market. Therefore, until long-term data are available for rosiglitazone, liver enzyme monitoring is recommended.