The Diabetes Pearl: Diabetes biobanking in The Netherlands

Background

Type 2 diabetes is associated with considerable comorbidity and severe complications, which reduce quality of life of the patients and require high levels of healthcare. The Diabetes Pearl is a large cohort of patients diagnosed with type 2 diabetes, covering different geographical areas in the Netherlands. The aim of the study is to create a research infrastructure that will allow the study of risk factors, including biomarkers and genetic determinants for severe diabetes complications.

Methods/design

Baseline examinations began November 2009 and will continue through 2012. By the end of 2012, it is expected that 7000 patients with type 2 diabetes will be included in the Diabetes Pearl cohort. To ensure quality of the data collected, standard operation procedures were developed and used in all 8 recruitment centers. From all patients who provide informed consent, the following information is collected: personal information, medication use, physical examination (antropometry, blood pressure, electrocardiography (ECG), retina photographs, ankle-brachial index, peripheral vibration perception), self-report questionnaire (socio-economic status, lifestyle, (family) history of disease, and psychosocial well-being), laboratory measurements (glucose, A1c, lipid profile, kidney function), biobank material (storage of urine and blood samples and isolated DNA). All gathered clinical data and biobank information is uploaded to a database for storage on a national level. Biobanks are maintained locally at all recruitment centers.

Discussion

The Diabetes Pearl is large-scale cohort of type 2 diabetes patients in the Netherlands aiming to study risk factors, including biomarkers and genetic markers, for disease deterioration and the development of severe diabetes complications. As a result of the well-designed research design and the national coverage, the Diabetes Pearl data can be of great value to national and international researchers with an interest in diabetes related research.

C-reactive protein, fibrinogen, and cardiovascular disease prediction

BACKGROUND

There is debate about the value of assessing levels of C-reactive protein (CRP) and other biomarkers of inflammation for the prediction of first cardiovascular events.

METHODS

We analyzed data from 52 prospective studies that included 246,669 participants without a history of cardiovascular disease to investigate the value of adding CRP or fibrinogen levels to conventional risk factors for the prediction of cardiovascular risk. We calculated measures of discrimination and reclassification during follow-up and modeled the clinical implications of initiation of statin therapy after the assessment of CRP or fibrinogen.

RESULTS

The addition of information on high-density lipoprotein cholesterol to a prognostic model for cardiovascular disease that included age, sex, smoking status, blood pressure, history of diabetes, and total cholesterol level increased the C-index, a measure of risk discrimination, by 0.0050. The further addition to this model of information on CRP or fibrinogen increased the C-index by 0.0039 and 0.0027, respectively (P<0.001), and yielded a net reclassification improvement of 1.52% and 0.83%, respectively, for the predicted 10-year risk categories of "low" (<10%), "intermediate" (10% to <20%), and "high" (≥20%) (P<0.02 for both comparisons). We estimated that among 100,000 adults 40 years of age or older, 15,025 persons would initially be classified as being at intermediate risk for a cardiovascular event if conventional risk factors alone were used to calculate risk. Assuming that statin therapy would be initiated in accordance with Adult Treatment Panel III guidelines (i.e., for persons with a predicted risk of ≥20% and for those with certain other risk factors, such as diabetes, irrespective of their 10-year predicted risk), additional targeted assessment of CRP or fibrinogen levels in the 13,199 remaining participants at intermediate risk could help prevent approximately 30 additional cardiovascular events over the course of 10 years.

CONCLUSIONS

In a study of people without known cardiovascular disease, we estimated that under current treatment guidelines, assessment of the CRP or fibrinogen level in people at intermediate risk for a cardiovascular event could help prevent one additional event over a period of 10 years for every 400 to 500 people screened. (Funded by the British Heart Foundation and others.).

Vitamin D status, incident diabetes and prospective changes in glucose metabolism in older subjects: the Hoorn study

BACKGROUND AND AIMS

Vitamin D deficiency may contribute to impaired glucose metabolism and type 2 diabetes, especially in the elderly population. We aimed to evaluate whether baseline 25-hydroxyvitamin D (25[OH]D) levels are prospectively associated with deterioration of glucose metabolism and the incidence of diabetes.

METHODS AND RESULTS

We examined a subsample from the population based Hoorn study among older men and women. Physical examinations were performed from 2000 to 2001 and included measurements of 25(OH)D. Glucose tolerance tests and HbA1c measurements were performed at baseline and at a follow-up between 2007 and 2009. We included 351 study participants (51% females; 67.9 ± 5.7 years). Baseline 25(OH)D levels were 56.7 ± 18.8 nmol/L and follow-up visits were performed after 7.5 ± 0.5 years. Among 280 study participants without diabetes at baseline we recorded 45 cases of incident diabetes. There was no significant association of 25(OH)D with the incidence of diabetes and with fasting and 2h postload glucose levels at follow-up. In analyses adjusted for age, sex, and baseline HbA1c there was, however, a significant association of 25(OH)D with follow-up HbA1c levels (beta coefficient=-0.085, p=0.085). This association was attenuated after further adjustments for BMI (beta coefficient=-0.079, p=0.064).

CONCLUSIONS

In this study among the older population we observed no significant association of baseline 25(OH)D with glucose metabolism and incident diabetes. We found, however, a non-significant trend towards an inverse association of 25(OH)D with prospective changes in HbA1c that deserves further investigations.

Common carotid intima-media thickness measurements in cardiovascular risk prediction: a meta-analysis

CONTEXT

The evidence that measurement of the common carotid intima-media thickness (CIMT) improves the risk scores in prediction of the absolute risk of cardiovascular events is inconsistent.

OBJECTIVE

To determine whether common CIMT has added value in 10-year risk prediction of first-time myocardial infarctions or strokes, above that of the Framingham Risk Score.

DATA SOURCES

Relevant studies were identified through literature searches of databases (PubMed from 1950 to June 2012 and EMBASE from 1980 to June 2012) and expert opinion.

STUDY SELECTION

Studies were included if participants were drawn from the general population, common CIMT was measured at baseline, and individuals were followed up for first-time myocardial infarction or stroke.

DATA EXTRACTION

Individual data were combined into 1 data set and an individual participant data meta-analysis was performed on individuals without existing cardiovascular disease.

RESULTS

We included 14 population-based cohorts contributing data for 45,828 individuals. During a median follow-up of 11 years, 4007 first-time myocardial infarctions or strokes occurred. We first refitted the risk factors of the Framingham Risk Score and then extended the model with common CIMT measurements to estimate the absolute 10-year risks to develop a first-time myocardial infarction or stroke in both models. The C statistic of both models was similar (0.757; 95% CI, 0.749-0.764; and 0.759; 95% CI, 0.752-0.766). The net reclassification improvement with the addition of common CIMT was small (0.8%; 95% CI, 0.1%-1.6%). In those at intermediate risk, the net reclassification improvement was 3.6% in all individuals (95% CI, 2.7%-4.6%) and no differences between men and women.

CONCLUSION

The addition of common CIMT measurements to the Framingham Risk Score was associated with small improvement in 10-year risk prediction of first-time myocardial infarction or stroke, but this improvement is unlikely to be of clinical importance.

Vitamin D and cardiovascular disease: update and outlook

Accumulating evidence suggests that vitamin D may play a role for cardiovascular health. Expression of the vitamin D receptor (VDR) and enzymes for vitamin D metabolism have been identified in the vasculature as well as in the heart. VDR knock-out mice suffer from cardiovascular disease (CVD) and even selective VDR deletion in cardiomyocytes causes myocardial hypertrophy. Many, but not all observational studies showed that vitamin D deficiency is associated with CVD and its risk factors. Low concentrations of 25-hydroxyvitamin D (25(OH)D) are an independent risk factor for cardiovascular events, in particular for strokes and sudden cardiac deaths. Only few randomized controlled trials (RCTs) are available on this topic. These RCTs are frequently limited by the additional supplementation of calcium which may increase the risk of CVD events. RCTs with pure vitamin D supplementation have partially but not consistently shown beneficial effects on cardiovascular risk factors such as arterial hypertension. A number of large RCTs on the impact of vitamin D supplementation on cardiovascular events and mortality have already started but limitations of the study designs such as inclusion of individuals with relatively high 25(OH)D concentrations have to be considered. At present, the evidence is not sufficient for general recommendations to supplement vitamin D in order to prevent and treat CVD. It should, however, be noted that justification for the prevention and treatment of vitamin D deficiency comes from evidence based benefits of vitamin D supplementation on musculoskeletal health.

Development of vascular risk factors over 15 years in relation to cognition: the Hoorn Study

OBJECTIVES

To investigate the development of vascular risk factor levels at four points over 15 years in relation to late-life cognitive functioning.

DESIGN

Longitudinal population-based study.

SETTING

The Hoorn Study, a community-based cohort study of glucose metabolism and cardiovascular risk.

PARTICIPANTS

Three hundred eighty individuals without dementia (mean baseline age 57.7 ± 5.5).

MEASUREMENTS

Four extensive medical examinations were conducted over 15 years. Cognition was assessed in detail at the fourth examination. The time course of vascular risk factors across the examinations was compared between individuals in the highest tertile (good performance) and those in the lowest tertile (poor performance) of cognitive functioning on three cognitive domains (memory, information processing speed, and attention and executive functioning (A&EF)).

RESULTS

Individuals with poor information processing speed had higher levels of systolic blood pressure at baseline (mean difference (standard error) 11.6 (2.6) mmHg, P < .001) than those with good information processing speed. Individuals with poor A&EF had a higher waist:hip ratio (3.03 (1.15), P = .009), glycosylated hemoglobin (0.29% (0.10%), P = .005) and total cholesterol:high-density lipoprotein cholesterol ratio (0.38 (0.19), P = .04) at baseline than individuals with good A&EF, although the differences in vascular risk factor levels between the poor and good cognition group diminished with increasing age.

CONCLUSION

High blood pressure, adiposity, hypercholesterolemia, and hyperglycemia at midlife are associated with late-life cognitive dysfunction, but for most risk factors, this relationship gradually attenuates with increasing age. These results suggest that timing of vascular treatment strategies to prevent cognitive impairment is critical.

Glucocorticoid receptor gene polymorphisms are associated with reduced first-phase glucose-stimulated insulin secretion and disposition index in women, but not in men

AIM

Glucocorticoids are efficacious anti-inflammatory agents, but, in susceptible individuals, these drugs may induce glucose intolerance and diabetes by affecting β-cell function and insulin sensitivity. We assessed whether polymorphisms in the glucocorticoid receptor gene NR3C1 associate with measures of β-cell function and insulin sensitivity derived from hyperglycaemic clamps in subjects with normal or impaired glucose tolerance.

METHODS

A cross-sectional cohort study was conducted in four academic medical centres in the Netherlands and Germany. Four hundred and forty-nine volunteers (188 men; 261 women) were recruited with normal glucose tolerance (n=261) and impaired glucose tolerance (n=188). From 2-h hyperglycaemic clamps, first- and second-phase glucose-stimulated insulin secretion, as well as insulin sensitivity index and disposition index, were calculated. All participants were genotyped for the functional NR3C1 polymorphisms N363S (rs6195), BclI (rs41423247), ER22/23EK (rs6189/6190), 9β A/G (rs6198) and ThtIIII (rs10052957). Associations between these polymorphisms and β-cell function parameters were assessed.

RESULTS

In women, but not in men, the N363S polymorphism was associated with reduced disposition index (P=1.06 10(-4) ). Also only in women, the ER22/23EK polymorphism was associated with reduced first-phase glucose-stimulated insulin secretion (P=0.011) and disposition index (P=0.003). The other single-nucleotide polymorphisms were not associated with β-cell function. Finally, none of the polymorphisms was related to insulin sensitivity.

CONCLUSION

The N363S and ER22/23EK polymorphisms of the NR3C1 gene are negatively associated with parameters of β-cell function in women, but not in men.

Associations between the ankle-brachial index and cardiovascular and all-cause mortality are similar in individuals without and with type 2 diabetes: nineteen-year follow-up of a population-based cohort study

OBJECTIVE

In the general population, a low ankle-brachial index (ABI) (<0.9) is strongly associated with (cardiovascular) mortality. However, the association between the ABI and mortality may be weaker in individuals with diabetes, as ankle pressures may be elevated by medial arterial calcification and arterial stiffening, which occur more frequently in diabetes. Therefore, the aim of this study was to compare the association between ABI and mortality in individuals without and with diabetes.

RESEARCH DESIGN AND METHODS

We studied the associations between ABI and cardiovascular and all-cause mortality in 624 individuals from the Hoorn study, a population-based cohort of 50- to 75-year-old individuals (155 with diabetes and 469 without) followed for a median period of 17.2 years. Data were analyzed using Cox proportional hazards models.

RESULTS

During the follow-up period, 289 of 624 (46.3%) participants died (97 of 155 with and 192 of 469 without diabetes and 52 of 65 with and 237 of 559 without ABI <0.9): 85 (29.4%) of CVD (30 of 155 with and 55 of 469 without diabetes and 20 of 65 with and 65 of 559 without ABI <0.9). A low ABI was strongly associated with cardiovascular mortality (relative risk 2.57 [95% CI 1.50-4.40]) and all-cause mortality (2.02 [1.47-2.76]), after adjustment for Framingham risk factors. The associations of the ABI with mortality did not differ between individuals without and with diabetes for cardiovascular (P(interaction) = 0.45) or all-cause (P(interaction) = 0.63) mortality.

CONCLUSIONS

In the Hoorn Study, associations between ABI and cardiovascular and all-cause mortality were similar in individuals without and with diabetes. Future studies should investigate, in both individuals without and with diabetes, whether measurement of ABI can be used to guide treatment decisions.

Serum 25-hydroxyvitamin D and parathyroid hormone in relation to plasma B-type natriuretic peptide: the Hoorn Study

OBJECTIVE

A disturbed vitamin D-parathyroid hormone (PTH)-calcium axis may play a role in the pathogenesis of heart failure. Therefore, we investigated whether lower 25-hydroxyvitamin D (25(OH)D) and higher PTH are cross sectionally and after 8 years of follow-up associated with higher B-type natriuretic peptide (BNP) levels in older men and women.

DESIGN AND METHODS

We measured baseline 25(OH)D, PTH, and BNP in 502 subjects in 2000-2001 in the Hoorn Study, a population-based cohort. Follow-up BNP was available in 2007-2009 in 278 subjects. Subjects were categorized according to season- and sex-specific quartiles of 25(OH)D and PTH at baseline. We studied the association of 25(OH)D and PTH quartiles with BNP using linear regression analyses adjusting for confounders. Analyses were stratified by kidney function estimated glomerular filtration rate (eGFR; ≤60 ml/min per 1.73 m(2)) because of significant interaction.

RESULTS

At baseline, subjects had a mean age of 69.9±6.6 years, mean 25(OH)D level was 52.2±19.5 nmol/l and mean PTH 6.1±2.4 pmol/l. Cross sectionally, 25(OH)D was associated with BNP in subjects with impaired kidney function (eGFR ≤60 ml/min) only. The association attenuated after adjustment for PTH. PTH was cross sectionally associated with BNP, also in subjects with impaired kidney function only: regression coefficient of highest quartile 9.9 pmol/l (95% confidence interval 2.5, 17.4) with a significant trend across quartiles. Neither 25(OH)D nor PTH was associated with BNP in longitudinal analyses.

CONCLUSION

This study showed overall no strong association between 25(OH)D and BNP. However, PTH was associated with BNP in subjects with impaired kidney function and may point to a potential role in myocardial function.

Development of coronary heart disease and ischemic stroke in relation to fasting and 2-hour plasma glucose levels in the normal range

Background

Individuals who had normoglycemia but whose 2-hour plasma glucose (2hPG) concentrations did not return to the fasting plasma glucose (FPG) levels during an oral glucose tolerance test (OGTT) have been shown to have increased cardiovascular mortality. This is further investigated regarding to the first events of coronary heart disease (CHD) and ischemic stroke (IS).

Method

Data from 9 Finnish and Swedish cohorts comprising 3743 men and 3916 women aged 25 to 90 years who had FPG < 6.1 mmol/l and 2hPG < 7.8 mmol/l and free of CVD at enrolment were analyzed. Hazard ratios (HRs) for first CHD and IS events were estimated for the individuals with 2hPG > FPG (Group II) compared with those having 2hPG ≤ FPG (Group I).

Results

A total of 466 (115) CHD and 235 (106) IS events occurred in men (women) during a median follow-up of 16.4 years. Individuals in Group II were older and had greater body mass index, blood pressure, 2hPG and fasting insulin than those in Group I in both sexes. Multivariate adjusted HRs (95% confidence intervals) for incidence of CHD, IS, and composite CVD events (CHD + IS) in men were 1.13 (0.93-1.37), 1.40 (1.06-1.85) and 1.20 (1.01-1.42) in the Group II as compared with those in the Group I. The corresponding HRs in women were 1.33 (0.83-2.13), 0.94 (0.59-1.51) and 1.11 (0.79-1.54), respectively.

Conclusion

Within normoglycemic range individuals whose 2hPG did not return to their FPG levels during an OGTT had increased risk of CHD and IS.

Independent associations of glucose status and arterial stiffness with left ventricular diastolic dysfunction: an 8-year follow-up of the Hoorn Study

OBJECTIVE

To investigate relative contributions of glucose status and arterial stiffness to markers of left ventricular (LV) systolic and diastolic dysfunction after 8 years of follow-up.

RESEARCH DESIGN AND METHODS

In the population-based prospective Hoorn Study, 394 individuals with preserved LV systolic and diastolic function participated, of whom 87 had impaired glucose metabolism and 128 had type 2 diabetes. Measurements including arterial ultrasound and echocardiography were performed according to standardized protocols.

RESULTS

The presence of type 2 diabetes was associated with more severe LV systolic and diastolic dysfunction 8 years later: LV ejection fraction was 2.98% (95% CI 0.46-5.51) lower, and left atrial (LA) volume index, LV mass index, and tissue Doppler-derived E/e' were 3.71 mL/m(2) (1.20-6.22), 5.86 g/m(2.7) (2.94-8.78), and 1.64 units (0.95-2.33) higher, respectively. Furthermore, presence of impaired glucose metabolism or type 2 diabetes was associated with 8-year increases in LV mass index. More arterial stiffness (measured as a lower distensibility) was associated with LV diastolic dysfunction 8 years later: LA volume index, LV mass index, and E/e' at follow-up were higher. Subsequent adjustments for baseline mean arterial pressure and/or LV diastolic dysfunction did not eliminate these associations. Associations of type 2 diabetes and arterial stiffness with markers of LV diastolic dysfunction were largely independent of each other.

CONCLUSIONS

Both glucose status and arterial distensibility are independently associated with more severe LV diastolic dysfunction 8 years later and with deterioration of LV diastolic dysfunction. Therefore, type 2 diabetes and arterial stiffness may relate to LV diastolic dysfunction through different pathways.

Vitamin D, cardiovascular disease and mortality

A poor vitamin D status, i.e. low serum levels of 25-hydroxyvitamin D [25(OH)D], is common in the general population. This finding is of concern not only because of the classic vitamin D effects on musculoskeletal outcomes, but also because expression of the vitamin D receptor (VDR) and vitamin D metabolizing enzymes in the heart and blood vessels suggests a role of vitamin D in the cardiovascular system. VDR-knockout mice suffer from cardiovascular disease (CVD), and various experimental studies suggest cardiovascular protection by vitamin D, including antiatherosclerotic, anti-inflammatory and direct cardio-protective actions, beneficial effects on classic cardiovascular risk factors as well as suppression of parathyroid hormone (PTH) levels. In epidemiological studies, low levels of 25(OH)D are associated with increased risk of CVD and mortality. Data from randomized controlled trials (RCTs) are sparse and have partially, but not consistently, shown some beneficial effects of vitamin D supplementation on cardiovascular risk factors (e.g. arterial hypertension). We have insufficient data on vitamin D effects on cardiovascular events, but meta-analyses of RCTs indicate that vitamin D may modestly reduce all-cause mortality. Despite accumulating data suggesting that a sufficient vitamin D status may protect against CVD, we still must wait for results of large-scale RCTs before raising general recommendations for vitamin D in the prevention and treatment of CVD. In current clinical practice, the overall risks and costs of vitamin D supplementation should be weighed against the potential adverse consequences of untreated vitamin D deficiency.

Albuminuria and cognitive functioning in an older population: the Hoorn study

BACKGROUND/AIMS

Markers of vascular disease elsewhere in the body may reflect vascular abnormalities in the brain relevant to age-related cognitive decline and dementia. We examined the association between albuminuria, as a marker of microvascular damage, and cognition in older individuals.

METHODS

380 individuals (age 73 ± 6 years), participating in the population-based Hoorn Study, underwent extensive neuropsychological examination in 2005-2008, and urinary albumin-to-creatinine ratios measurements in 2000-2001 (n = 378) and/or 2005-2008 (n = 346). Cognition was expressed in z-scores on 6 domains.

RESULTS

In 2000-2001, 42 participants were with and 336 without albuminuria, and in 2005-2008 51 were with and 295 were without. In age-, sex- and premorbid IQ-adjusted analyses, participants with albuminuria 5-7 years earlier had slightly lower z-scores for the domains attention and executive functioning [mean difference: -0.21 (95% CI -0.40 to -0.02)] and language [-0.36 (95% CI -0.63 to -0.09)]. No statistically significant differences in cognition were found between participants with and without albuminuria at the time of neuropsychological testing.

CONCLUSION

Albuminuria predicts future modest cognitive decrements, but concurrent albuminuria is unrelated to cognitive functioning. The link between albuminuria and cognitive dysfunction may convey an etiological message, but because effect sizes were modest its value in prognostic models for cognitive decline may be limited.

One risk assessment tool for cardiovascular disease, type 2 diabetes, and chronic kidney disease

OBJECTIVE

Individuals at high risk for chronic cardiometabolic disease (cardiovascular disease [CVD], type 2 diabetes, and chronic kidney disease [CKD]) share many risk factors and would benefit from early intervention. We developed a nonlaboratory-based risk-assessment tool for identification of people at high cardiometabolic disease risk.

RESEARCH DESIGN AND METHODS

Data of three population-based cohorts from different regions of the Netherlands were merged. Participants were 2,840 men and 3,940 women, white, aged 28-85 years, free from CVD, type 2 diabetes, and CKD diagnosis at baseline. The outcome was developing cardiometabolic disease during 7 years follow-up.

RESULTS

Age, BMI, waist circumference, antihypertensive treatment, smoking, family history of myocardial infarction or stroke, and family history of diabetes were significant predictors, whereas former smoking, history of gestational diabetes, and use of lipid-lowering medication were not. The models showed acceptable calibration (Hosmer and Lemeshow statistics, P > 0.05) and discrimination (area under the receiver operating characteristic [ROC] curve 0.82 [95% CI 0.81-0.83] for women and 0.80 [0.78-0.82] for men). Discrimination of individual outcomes was lowest for diabetes (area under the ROC curve 0.70 for men and 0.73 for women) and highest for CVD mortality (0.83 for men and 0.85 for women).

CONCLUSIONS

We demonstrate that a single risk stratification tool can identify people at high risk for future CVD, type 2 diabetes, and/or CKD. The present risk-assessment tool can be used for referring the highest risk individuals to health care for further (multivariable) risk assessment and may as such serve as an important part of prevention programs targeting chronic cardiometabolic disease.

Common variants in the type 2 diabetes KCNQ1 gene are associated with impairments in insulin secretion during hyperglycaemic glucose clamp

BACKGROUND

Genome-wide association studies in Japanese populations recently identified common variants in the KCNQ1 gene to be associated with type 2 diabetes. We examined the association of these variants within KCNQ1 with type 2 diabetes in a Dutch population, investigated their effects on insulin secretion and metabolic traits and on the risk of developing complications in type 2 diabetes patients.

METHODOLOGY

The KCNQ1 variants rs151290, rs2237892, and rs2237895 were genotyped in a total of 4620 type 2 diabetes patients and 5285 healthy controls from the Netherlands. Data on macrovascular complications, nephropathy and retinopathy were available in a subset of diabetic patients. Association between genotype and insulin secretion/action was assessed in the additional sample of 335 individuals who underwent a hyperglycaemic clamp.

PRINCIPAL FINDINGS

We found that all the genotyped KCNQ1 variants were significantly associated with type 2 diabetes in our Dutch population, and the association of rs151290 was the strongest (OR 1.20, 95% CI 1.07-1.35, p = 0.002). The risk C-allele of rs151290 was nominally associated with reduced first-phase glucose-stimulated insulin secretion, while the non-risk T-allele of rs2237892 was significantly correlated with increased second-phase glucose-stimulated insulin secretion (p = 0.025 and 0.0016, respectively). In addition, the risk C-allele of rs2237892 was associated with higher LDL and total cholesterol levels (p = 0.015 and 0.003, respectively). We found no evidence for an association of KCNQ1 with diabetic complications.

CONCLUSIONS

Common variants in the KCNQ1 gene are associated with type 2 diabetes in a Dutch population, which can be explained at least in part by an effect on insulin secretion. Furthermore, our data suggest that KCNQ1 is also associated with lipid metabolism.

Discontinuation of statins among patients with type 2 diabetes

BACKGROUND

Statins play an important role in the prevention of cardiovascular disease in type 2 diabetes. Several studies have reported low adherence with statins among patients with type 2 diabetes. Studies comparing discontinuation of statins compared with discontinuation of oral anti-diabetics within the same individuals before and after initiation of oral anti-diabetic drugs are not available. The aim of this study was to describe discontinuation among patients with type 2 diabetes prescribed statins prior to and after initiation of oral anti-diabetics and to compare statin discontinuation with discontinuation of oral anti-diabetics.

METHODS

We report an observational cohort study among patients initiating treatment with statins prior to or after initiation of oral anti-diabetics between 1999 and 2007. Patients were classified as starting statins prior to initiation (Prior users) or after initiation (After users) of anti-diabetics. Discontinuation was defined as an interval of 180 days or more between the theoretical end date of a statin/anti-diabetic prescription and the dispensing date of the next statin/anti-diabetic prescription.

RESULTS AND CONCLUSIONS

We included 3323 starters with oral anti-diabetic drugs in our study; 2072 patients initiated statins in the period of observation. Discontinuation rates for statins were higher compared with oral anti-diabetics (52.1 vs 15.0%). After users discontinued statin therapy more frequently compared to prior users (62.8 vs 48.2%). Discontinuation of statins is higher compared with anti-diabetic discontinuation. Patients starting statins after the initiation of oral anti-diabetic treatment are more likely to discontinue treatment than patients who initiate statins before the start of oral anti-diabetics.

Plasma sCD36 is associated with markers of atherosclerosis, insulin resistance and fatty liver in a nondiabetic healthy population

OBJECTIVES

Insulin resistance is associated with increased CD36 expression in a number of tissues. Moreover, excess macrophage CD36 may initiate atherosclerotic lesions. The aim of this study was to determine whether plasma soluble CD36 (sCD36) was associated with insulin resistance, fatty liver and carotid atherosclerosis in nondiabetic subjects.

METHODS

In 1296 healthy subjects without diabetes or hypertension recruited from 19 centres in 14 European countries (RISC study), we determined the levels of sCD36, adiponectin, lipids and liver enzymes, insulin sensitivity (M/I) by euglycaemic-hyperinsulinaemic clamp, carotid atherosclerosis as intima-media thickness (IMT) and two estimates of fatty liver, the fatty liver index (FLI) and liver fat percentage (LF%).

RESULTS

IMT, FLI, LF%, presence of the metabolic syndrome, impaired glucose regulation, insulin and triglycerides increased across sCD36 quartiles (Q2-Q4), whereas adiponectin and M/I decreased (P ≤ 0.01). sCD36 was lower in women than in men (P = 0.045). Log sCD36 showed a bimodal distribution, and amongst subjects with sCD36 within the log-normal distribution (log-normal population, n = 1029), sCD36 was increased in subjects with impaired glucose regulation (P = 0.045), metabolic syndrome (P = 0.006) or increased likelihood of fatty liver (P < 0.001). sCD36 correlated significantly with insulin, triglycerides, M/I and FLI (P < 0.05) after adjustment for study centre, gender, age, glucose tolerance status, smoking habits and alcohol consumption. In the log-normal population, these relationships were stronger than in the total study population and, additionally, sCD36 was significantly associated with LF% and IMT (P < 0.05).

CONCLUSIONS

In this cross-sectional study of nondiabetic subjects, sCD36 was significantly associated with indices of insulin resistance, carotid atherosclerosis and fatty liver. Prospective studies are needed to further evaluate the role of sCD36 in the inter-relationship between atherosclerosis, fatty liver and insulin resistance.

Global prevalence and major risk factors of diabetic retinopathy

OBJECTIVE

To examine the global prevalence and major risk factors for diabetic retinopathy (DR) and vision-threatening diabetic retinopathy (VTDR) among people with diabetes.

RESEARCH DESIGN AND METHODS

A pooled analysis using individual participant data from population-based studies around the world was performed. A systematic literature review was conducted to identify all population-based studies in general populations or individuals with diabetes who had ascertained DR from retinal photographs. Studies provided data for DR end points, including any DR, proliferative DR, diabetic macular edema, and VTDR, and also major systemic risk factors. Pooled prevalence estimates were directly age-standardized to the 2010 World Diabetes Population aged 20-79 years.

RESULTS

A total of 35 studies (1980-2008) provided data from 22,896 individuals with diabetes. The overall prevalence was 34.6% (95% CI 34.5-34.8) for any DR, 6.96% (6.87-7.04) for proliferative DR, 6.81% (6.74-6.89) for diabetic macular edema, and 10.2% (10.1-10.3) for VTDR. All DR prevalence end points increased with diabetes duration, hemoglobin A(1c), and blood pressure levels and were higher in people with type 1 compared with type 2 diabetes.

CONCLUSIONS

There are approximately 93 million people with DR, 17 million with proliferative DR, 21 million with diabetic macular edema, and 28 million with VTDR worldwide. Longer diabetes duration and poorer glycemic and blood pressure control are strongly associated with DR. These data highlight the substantial worldwide public health burden of DR and the importance of modifiable risk factors in its occurrence. This study is limited by data pooled from studies at different time points, with different methodologies and population characteristics.

The Heritability of HbA1c and Fasting Blood Glucose in Different Measurement Settings

In an extended twin study we estimated the heritability of fasting HbA1c and blood glucose levels. Blood glucose was assessed in different settings (at home and in the clinic). We tested whether the genetic factors influencing fasting blood glucose levels overlapped with those influencing HbA1c and whether the same genetic factors were expressed across different settings. Fasting blood glucose was measured at home and during two visits to the clinic in 77 healthy families with same-sex twins and siblings, aged 20 to 45 years. HbA1c was measured during the first clinic visit. A 4-variate genetic structural equation model was used that estimated the heritability of each trait and the genetic correlations among traits. Heritability explained 75% of the variance in HbA1c. The heritability of fasting blood glucose was estimated at 66% at home and lower in the clinic (57% and 38%). Fasting blood glucose levels were significantly correlated across settings (0.34 <r< 0.54), mostly due to a common set of genes that explained between 53% and 95% of these correlations. Correlations between HbA1c and fasting blood glucoses were low (0.11 <r< 0.23) and genetic factors influencing HbA1c and fasting glucose were uncorrelated. These results suggest that in healthy adults the genes influencing HbA1c and fasting blood glucose reflect different aspects of the glucose metabolism. As a consequence these two glycemic parameters can not be used interchangeably in diagnostic procedures or in studies attempting to find genes for diabetes. Both contribute unique (genetic) information.

Vitamin D in relation to myocardial structure and function after eight years of follow-up: the Hoorn study

BACKGROUND AND AIMS

To investigate associations between baseline serum 25-hydroxyvitamin D [25(OH)D] levels and myocardial structure and function after 8 years of follow-up in older Dutch subjects.

METHODS

We included 256 subjects of the Hoorn Study, a population-based cohort. They underwent a standardized 2-dimensional echocardiogram at baseline between 2000 and 2001, and again between 2007 and 2009. We studied the association of 25(OH)D quartiles with echocardiographic measures of the left ventricular mass index (LVMI), left ventricular systolic function and markers of diastolic function using linear regression analyses.

RESULTS

At baseline, subjects had a mean age of 67.4 ± 5.2 years and 41.4% had prior cardiovascular disease (CVD). Low serum 25(OH)D levels were only associated with higher LVMI at 8-year follow-up in subjects without prior CVD and in subjects with low kidney function (median estimated glomerular filtration rate ≤77.5 ml/min/1.73m(2)). The associations attenuated after adjustments for parathyroid hormone (PTH), which was associated with higher LVMI (g/m(2.7)) in subjects with low kidney function (regression coefficient highest quartile 6.3, 95% CI: 0.2, 12.5).

CONCLUSION

This study showed no strong associations of 25(OH)D with myocardial structure and function. However, PTH - a possible modifiable mediator in the relation between 25(OH)D and myocardial structure - was positively associated with LVMI in subjects with low kidney function.

Self-monitoring of blood glucose in patients with type 2 diabetes mellitus who are not using insulin

BACKGROUND

Self-monitoring of blood glucose (SMBG) has been found to be effective for patients with type 1 diabetes and for patients with type 2 diabetes using insulin. There is much debate on the effectiveness of SMBG as a tool in the self-management for patients with type 2 diabetes who are not using insulin.

OBJECTIVES

To assess the effects of SMBG in patients with type 2 diabetes mellitus who are not using insulin.

SEARCH METHODS

Multiple electronic bibliographic and ongoing trial databases were searched supplemented with handsearches of references of retrieved articles (date of last search: 07 July 2011).

SELECTION CRITERIA

Randomised controlled trials investigating the effects of SMBG compared with usual care, self-monitoring of urine glucose (SMUG) or both in patients with type 2 diabetes who where not using insulin. Studies that used glycosylated haemoglobin A(1c) (HbA(1c)) as primary outcome were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from included studies and evaluated the studies' risk of bias. Data from the studies were compared to decide whether they were sufficiently homogeneous to pool in a meta-analysis. Primary outcomes were HbA(1c), health-related quality of life, well-being and patient satisfaction. Secondary outcomes were fasting plasma glucose level, hypoglycaemic episodes, morbidity, adverse effects and costs.

MAIN RESULTS

Twelve randomised controlled trials were included and evaluated outcomes in 3259 randomised patients. Intervention duration ranged from 6 months (26 weeks) to 12 months (52 weeks). Nine trials compared SMBG with usual care without monitoring, one study compared SMBG with SMUG, one study was a three-armed trial comparing SMBG and SMUG with usual care and one study was a three-armed trial comparing less intensive SMBG and more intensive SMBG with a control group. Seven out of 11 studies had a low risk of bias for most indicators. Meta-analysis of studies including patients with a diabetes duration of one year or more showed a statistically significant SMBG induced decrease in HbA(1c) at up to six months follow-up (-0.3; 95% confidence interval (CI) -0.4 to -0.1; 2324 participants, nine trials), yet an overall statistically non-significant SMBG induced decrease was seen at 12 month follow-up (-0.1; 95% CI -0.3 to 0.04; 493 participants, two trials). Qualitative analysis of the effect of SMBG on well-being and quality of life showed no effect on patient satisfaction, general well-being or general health-related quality of life. Two trials reported costs of self-monitoring: One trial compared the costs of self-monitoring of blood glucose with self-monitoring of urine glucose based on nine measurements per week and with the prices in US dollars for self-monitoring in 1990. Authors concluded that total costs in the first year of self-monitoring of blood glucose, with the purchase of a reflectance meter were 12 times more expensive than self-monitoring of urine glucose ($481 or 361 EURO [11/2011 conversion] versus $40 or 30 EURO [11/2011 conversion]). Another trial reported a full economical evaluation of the costs and effects of self-monitoring. At the end of the trial, costs for the intervention were £89 (104 EURO [11/2011 conversion]) for standardized usual care (control group), £181 (212 EURO [11/2011 conversion]) for the less intensive self-monitoring group and £173 (203 EURO [11/2011 conversion]) for the more intensive self-monitoring group. Higher losses to follow-up in the more intensive self-monitoring group were responsible for the difference in costs, compared to the less intensive self-monitoring group.There were few data on the effects on other outcomes and these effects were not statistically significant. None of the studies reported data on morbidity.

AUTHORS' CONCLUSIONS

From this review, we conclude that when diabetes duration is over one year, the overall effect of self-monitoring of blood glucose on glycaemic control in patients with type 2 diabetes who are not using insulin is small up to six months after initiation and subsides after 12 months. Furthermore, based on a best-evidence synthesis, there is no evidence that SMBG affects patient satisfaction, general well-being or general health-related quality of life. More research is needed to explore the psychological impact of SMBG and its impact on diabetes specific quality of life and well-being, as well as the impact of SMBG on hypoglycaemia and diabetic complications.

Postprandial metabolic responses to mixed versus liquid meal tests in healthy men and men with type 2 diabetes

AIMS

Compare metabolic responses after mixed versus liquid meals of similar caloric/nutritional content in healthy and type 2 diabetes (T2D) subjects.

METHODS

Ten healthy men and 10 men with T2D received mixed and liquid meals after an overnight fast. Classical (insulinogenic index; insulin/glucose areas under curves, AUC(insulin)/AUC(glucose)) and model-based (beta-cell glucose sensitivity; rate sensitivity; potentiation factor ratio, PFR) beta-cell function estimates were calculated. Between-meal differences in glucose, insulin, C-peptide, triglyceride (TG), beta-cell function and oral glucose insulin sensitivity (OGIS) and between-meal correlations for beta-cell function and OGIS were evaluated.

RESULTS

Among healthy subjects, beta-cell function and OGIS were similar between meals. C-peptide (p=0.03), insulin (p=0.002), AUC(insulin)/AUC(glucose) (p=0.004) and insulin secretion (p=0.04) were higher after the liquid meal. Among T2D subjects, glucose, insulin, C-peptide, beta-cell function, and OGIS were similar. PFR was higher (p=0.004) and TG increased more slowly (p=0.002) after the liquid meal. OGIS and beta-cell function were correlated during both meals in both groups (r=0.66-0.98), except incremental AUC(insulin)/AUC(glucose), rate sensitivity, and, in healthy subjects, PFR.

CONCLUSIONS

Metabolic responses after mixed or liquid meals of similar content were highly correlated in T2D and healthy subjects. In T2D, the liquid meal produced beta-cell function estimates generally similar to the mixed meal.

Vitamin D, cardiovascular disease and mortality

A poor vitamin D status, i.e. low serum levels of 25-hydroxyvitamin D [25(OH)D], is common in the general population. This finding is of concern not only because of the classic vitamin D effects on musculoskeletal outcomes, but also because expression of the vitamin D receptor (VDR) and vitamin D metabolizing enzymes in the heart and blood vessels suggests a role of vitamin D in the cardiovascular system. VDR-knockout mice suffer from cardiovascular disease (CVD), and various experimental studies suggest cardiovascular protection by vitamin D, including antiatherosclerotic, anti-inflammatory and direct cardio-protective actions, beneficial effects on classic cardiovascular risk factors as well as suppression of parathyroid hormone (PTH) levels. In epidemiological studies, low levels of 25(OH)D are associated with increased risk of CVD and mortality. Data from randomized controlled trials (RCTs) are sparse and have partially, but not consistently, shown some beneficial effects of vitamin D supplementation on cardiovascular risk factors (e.g. arterial hypertension). We have insufficient data on vitamin D effects on cardiovascular events, but meta-analyses of RCTs indicate that vitamin D may modestly reduce all-cause mortality. Despite accumulating data suggesting that a sufficient vitamin D status may protect against CVD, we still must wait for results of large-scale RCTs before raising general recommendations for vitamin D in the prevention and treatment of CVD. In current clinical practice, the overall risks and costs of vitamin D supplementation should be weighed against the potential adverse consequences of untreated vitamin D deficiency.