Identification, Heritability, and Relation With Gene Expression of Novel DNA Methylation Loci for Blood Pressure

We conducted an epigenome-wide association study meta-analysis on blood pressure (BP) in 4820 individuals of European and African ancestry aged 14 to 69. Genome-wide DNA methylation data from peripheral leukocytes were obtained using the Infinium Human Methylation 450k BeadChip. The epigenome-wide association study meta-analysis identified 39 BP-related CpG sites with P<1×10^-5. In silico replication in the CHARGE consortium of 17 010 individuals validated 16 of these CpG sites. Out of the 16 CpG sites, 13 showed novel association with BP. Conversely, out of the 126 CpG sites identified as being associated (P<1×10^-7) with BP in the CHARGE consortium, 21 were replicated in the current study. Methylation levels of all the 34 CpG sites that were cross-validated by the current study and the CHARGE consortium were heritable and 6 showed association with gene expression. Furthermore, 9 CpG sites also showed association with BP with P<0.05 and consistent direction of the effect in the meta-analysis of the Finnish Twin Cohort (199 twin pairs and 4 singletons; 61% monozygous) and the Netherlands Twin Register (266 twin pairs and 62 singletons; 84% monozygous). Bivariate quantitative genetic modeling of the twin data showed that a majority of the phenotypic correlations between methylation levels of these CpG sites and BP could be explained by shared unique environmental rather than genetic factors, with 100% of the correlations of systolic BP with cg19693031 (TXNIP) and cg00716257 (JDP2) determined by environmental effects acting on both systolic BP and methylation levels.

Genome-wide meta-analysis identifies six novel loci associated with habitual coffee consumption

Coffee, a major dietary source of caffeine, is among the most widely consumed beverages in the world and has received considerable attention regarding health risks and benefits. We conducted a genome-wide (GW) meta-analysis of predominately regular-type coffee consumption (cups per day) among up to 91,462 coffee consumers of European ancestry with top single-nucleotide polymorphisms (SNPs) followed-up in ~30 062 and 7964 coffee consumers of European and African-American ancestry, respectively. Studies from both stages were combined in a trans-ethnic meta-analysis. Confirmed loci were examined for putative functional and biological relevance. Eight loci, including six novel loci, met GW significance (log10Bayes factor (BF)>5.64) with per-allele effect sizes of 0.03-0.14 cups per day. Six are located in or near genes potentially involved in pharmacokinetics (ABCG2, AHR, POR and CYP1A2) and pharmacodynamics (BDNF and SLC6A4) of caffeine. Two map to GCKR and MLXIPL genes related to metabolic traits but lacking known roles in coffee consumption. Enhancer and promoter histone marks populate the regions of many confirmed loci and several potential regulatory SNPs are highly correlated with the lead SNP of each. SNP alleles near GCKR, MLXIPL, BDNF and CYP1A2 that were associated with higher coffee consumption have previously been associated with smoking initiation, higher adiposity and fasting insulin and glucose but lower blood pressure and favorable lipid, inflammatory and liver enzyme profiles (P<5 × 10(-8)).Our genetic findings among European and African-American adults reinforce the role of caffeine in mediating habitual coffee consumption and may point to molecular mechanisms underlying inter-individual variability in pharmacological and health effects of coffee.

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche

Age at menarche is a marker of timing of puberty in females. It varies widely between individuals, is a heritable trait and is associated with risks for obesity, type 2 diabetes, cardiovascular disease, breast cancer and all-cause mortality. Studies of rare human disorders of puberty and animal models point to a complex hypothalamic-pituitary-hormonal regulation, but the mechanisms that determine pubertal timing and underlie its links to disease risk remain unclear. Here, using genome-wide and custom-genotyping arrays in up to 182,416 women of European descent from 57 studies, we found robust evidence (P < 5 × 10(-8)) for 123 signals at 106 genomic loci associated with age at menarche. Many loci were associated with other pubertal traits in both sexes, and there was substantial overlap with genes implicated in body mass index and various diseases, including rare disorders of puberty. Menarche signals were enriched in imprinted regions, with three loci (DLK1-WDR25, MKRN3-MAGEL2 and KCNK9) demonstrating parent-of-origin-specific associations concordant with known parental expression patterns. Pathway analyses implicated nuclear hormone receptors, particularly retinoic acid and γ-aminobutyric acid-B2 receptor signalling, among novel mechanisms that regulate pubertal timing in humans. Our findings suggest a genetic architecture involving at least hundreds of common variants in the coordinated timing of the pubertal transition.

Role of premixed insulin analogues in the treatment of patients with type 2 diabetes mellitus: a narrative review

Because of the progressive nature of type 2 diabetes mellitus (T2DM), insulin therapy will eventually become necessary in most patients. Recent evidence suggests that maintaining optimal glycemic control by early insulin therapy can reduce the risk of microvascular and macrovascular complications in patients with T2DM. The present review focuses on relevant clinical evidence supporting the use of premixed insulin analogues in T2DM when intensifying therapy, and as starter insulins in insulin-naïve patients. Our aim is to provide relevant facts and clinical evidence useful in the decision-making process of treatment selection and individualized treatment goal setting to obtain sustained blood glucose control.

The prevalence of metabolic syndrome and metabolically healthy obesity in Europe: a collaborative analysis of ten large cohort studies

BACKGROUND

Not all obese subjects have an adverse metabolic profile predisposing them to developing type 2 diabetes or cardiovascular disease. The BioSHaRE-EU Healthy Obese Project aims to gain insights into the consequences of (healthy) obesity using data on risk factors and phenotypes across several large-scale cohort studies. Aim of this study was to describe the prevalence of obesity, metabolic syndrome (MetS) and metabolically healthy obesity (MHO) in ten participating studies.

METHODS

Ten different cohorts in seven countries were combined, using data transformed into a harmonized format. All participants were of European origin, with age 18-80 years. They had participated in a clinical examination for anthropometric and blood pressure measurements. Blood samples had been drawn for analysis of lipids and glucose. Presence of MetS was assessed in those with obesity (BMI ≥ 30 kg/m2) based on the 2001 NCEP ATP III criteria, as well as an adapted set of less strict criteria. MHO was defined as obesity, having none of the MetS components, and no previous diagnosis of cardiovascular disease.

RESULTS

Data for 163,517 individuals were available; 17% were obese (11,465 men and 16,612 women). The prevalence of obesity varied from 11.6% in the Italian CHRIS cohort to 26.3% in the German KORA cohort. The age-standardized percentage of obese subjects with MetS ranged in women from 24% in CHRIS to 65% in the Finnish Health2000 cohort, and in men from 43% in CHRIS to 78% in the Finnish DILGOM cohort, with elevated blood pressure the most frequently occurring factor contributing to the prevalence of the metabolic syndrome. The age-standardized prevalence of MHO varied in women from 7% in Health2000 to 28% in NCDS, and in men from 2% in DILGOM to 19% in CHRIS. MHO was more prevalent in women than in men, and decreased with age in both sexes.

CONCLUSIONS

Through a rigorous harmonization process, the BioSHaRE-EU consortium was able to compare key characteristics defining the metabolically healthy obese phenotype across ten cohort studies. There is considerable variability in the prevalence of healthy obesity across the different European populations studied, even when unified criteria were used to classify this phenotype.

Meta-analyses identify 13 loci associated with age at menopause and highlight DNA repair and immune pathways

To newly identify loci for age at natural menopause, we carried out a meta-analysis of 22 genome-wide association studies (GWAS) in 38,968 women of European descent, with replication in up to 14,435 women. In addition to four known loci, we identified 13 loci newly associated with age at natural menopause (at P < 5 × 10(-8)). Candidate genes located at these newly associated loci include genes implicated in DNA repair (EXO1, HELQ, UIMC1, FAM175A, FANCI, TLK1, POLG and PRIM1) and immune function (IL11, NLRP11 and PRRC2A (also known as BAT2)). Gene-set enrichment pathway analyses using the full GWAS data set identified exoDNase, NF-κB signaling and mitochondrial dysfunction as biological processes related to timing of menopause.

From shared care to disease management: key-influencing factors

Background

In order to improve the quality of care of chronically ill patients the traditional boundaries between primary and secondary care are questioned. To demolish these boundaries so-called ‘shared care’ projects have been initiated in which different ways of substitution of care are applied. When these projects end, disease management may offer a solution to expand the achieved co-operation between primary and secondary care.

Objective

Answering the question: What key factors influence the development and implementation of shared care projects from a management perspective and how are they linked?

Theory

The theoretical framework is based on the concept of the learning organisation.

Design

Reference point is a multiple case study that finally becomes a single case study. Data are collected by means of triangulation. The studied cases concern two interrelated Dutch shared care projects for type 2 diabetic patients, that in the end proceed as one disease management project.

Results

In these cases the predominant key-influencing factors appear to be the project management, commitment and local context, respectively. The factor project management directly links the latter two, albeit managing both appear prerequisites to its success. In practice this implies managing the factors' interdependency by the application of change strategies and tactics in a committed and skilful way.

Conclusion

Project management, as the most important and active key factor, is advised to cope with the interrelationships of the influencing factors in a gradually more fundamental way by using strategies and tactics that enable learning processes. Then small-scale shared care projects may change into a disease management network at a large scale, which may yield the future blueprint to proceed.

[Empty sella syndrome as the cause of panhypopituitarism]

In two patients, men aged 78 and 42 years respectively, an empty-sella syndrome was found. The first patient presented with chronic fatigue, in the second the empty sella was the late result of prior neurosurgery followed by external irradiation. Both suffered from panhypopituitarism. In both cases the diagnosis was confirmed following laboratory tests and MRI. Hormone-replacement therapy was found to provide adequate treatment. The course of the empty-sella syndrome is usually benign and with adequate hormone-replacement therapy a good quality of life is maintained.

Design of a consumer health record for supporting the patient-centered management of chronic diseases

This paper describes and discusses the design and usage of a shareable consumer health record system to investigate whether these systems can assist in the management of chronic diseases. This web-based system that can be used both by care providers and patients contains medical and patient information, provides access to websites that contain quality information, provides guideline-based advice, allows discussion between patients and allows us to interrogate both patients and care providers on a regular basis in order to get a good impression of the utility of such a consumer record for both chronic patients and the physicians and nurses. A health record system that was developed for the area of Diabetes is presented as an example.

Clinical experience with Sandostatin LAR in patients with acromegaly

Patients with acromegaly, who are not cured after transsphenoidal adenomectomy, may be treated with external irradiation and/or octreotide injections. Recently, a long-acting formulation of octreotide (Sandostatin LAR has become available in clinical practice. We assessed the effects of treatment with this long-acting octreotide in 18 consecutive patients with acromegaly treated in our center, who had persistent signs and symptoms of acromegaly despite transsphenoidal surgery with (n=7) or without irradiation (n=11). Twelve had already been treated with regular Sandostatin for a period of 0.5-8 years in dosages of 3 x 50 to 3 x 300 mcg s.c. (median daily dose 300 mcg). All patients started with i.m. injections of 20 mg Sandostatin LAR every 4 weeks. In the patients who started treatment with octreotide for the first time, mean serum IGF-1 levels (measured by IRMA, Nichols Diagnostics) decreased from 634+/-229 to 255+/-88 ng/ml after 3 months, 271+/-81 ng/ml after 1 year and 263+/-97 ng/ml after 2 years (all P<0.05), while random GH levels (DELFIA, Wallac) decreased from 6.6 (range 3.1-67.0) to 2.1 (0.5-3.1) mU/l after 2 years (P<0.05). In the 12 patients who had already been treated with octreotide, mean IGF-1 also fell, from 367+/-193 to 331+/-195 ng/ml (P=0.023) after 3 months, to 342+/-191 ng/ml after 1 year and 277+/-169 ng/ml (P=0.002) after 2 years, while random GH levels decreased from 4.5 (1.1-46) mU/l at baseline to 2.1 (0.4-23.0) after 2 years (P=0.003). Therefore, the average decrease of IGF-1 was 10% after 3 months and 25% after 2 years. One patient had a decrease of less than 5% (but her IGF-1 was normal, 193 ng/ml), and one patient showed no response to both regular and long-acting Sandostatin (ave. IGF-1, 755 ng/ml). No specific side-effects occurred. One patient chose to return to t.i.d. injection of regular octreotide because of slight worsening of her complaints of headache despite normal IGF-1 levels. All other patients favoured continuation of the monthly injections. In six patients, the dose had to be increased to 30-40 mg monthly because the IGF-1 levels still remained elevated. Sandostatin LAR may be considered a great improvement for the treatment of patients with (symptomatic) acromegaly.

Substitution model with central role for nurse specialist is justified in the care for stable type 2 diabetic outpatients

AIM OF THE STUDY

Assessment of effects on quality of care, in terms of patient outcomes, when tasks in the care for outpatients with stable type 2 diabetes are transferred from internist to nurse specialist and from outpatient clinic to general practice.

BACKGROUND

For the management of chronic diseases with a high prevalence and requiring current monitoring, it is suggested that substitution of care may be an appropriate solution to safeguard high quality care.

DESIGN AND METHODS

A 12-month nonequivalent control group design was used. General practitioners (GPs) referring diabetes patients to the University Hospital Maastricht were asked to choose for the traditional model or the nurse specialist model. Informed consent was obtained from patients with stable diabetes type 2 attending these practices. All patients received care according to the model chosen by their GP. Identified outcomes were: clinical status, health status, self-care behaviour, knowledge of diabetes, patient satisfaction, and consultation with care-providers.

RESULTS

In the control group (n=47) no patients were treated with oral hypoglycaemic agents (OHA) only. The control group was compared with an intervention subgroup (n=52) also without patients receiving OHA only. Clinical data were available for all patients. Patients without complete data from questionnaires had better mean concentration of HbA1c than patients with complete data (P=0.004). The traditional care model and the nurse specialist model achieved equal outcomes, while glycaemic control of patients in the nurse specialist model improved (from 8.6% to 8.3%) but deteriorated in the traditional model (from 8.6% to 8.8%; P-value between groups=0.001).

CONCLUSIONS

The model with nurse specialists taking on roles and tasks beyond those traditionally regarded as their remit as well as new ones, is effective for the care of stable diabetic outpatients.

Ramipril and the development of diabetes

CONTEXT

Type 2 diabetes is a growing clinical and public health problem. Preventive efforts related to lifestyle modification are not always successful; therefore, alternative prevention strategies need to be studied.

OBJECTIVE

To investigate the effectiveness of ramipril, an angiotensin-converting enzyme inhibitor, in preventing diabetes among high-risk persons.

DESIGN, SETTING, AND PARTICIPANTS

The randomized, controlled Heart Outcomes Prevention Evaluation trial of 5720 patients older than 55 years without known diabetes but with vascular disease who were followed up for a mean of 4.5 years. The study included 267 hospitals in 19 countries and was conducted between 1994 and 1999.

INTERVENTION

Patients were randomly assigned to receive ramipril, up to 10 mg/d (n = 2837), or placebo (n = 2883).

MAIN OUTCOME MEASURE

Diagnosis of diabetes determined from self-report at follow-up visits every 6 months, compared between the 2 groups.

RESULTS

One hundred and two individuals (3.6%) in the ramipril group developed diabetes compared with 155 (5.4%) in the placebo group (relative risk [RR], 0.66; 95% confidence interval [CI], 0.51-0.85, P<.001). Similar results were noted when different diagnostic criteria were used; in the ramipril group, the RR for diagnosis of diabetes and hemoglobin A(1c) greater than 110% was 0.60 (95% CI, 0.43-0.85), for initiation of glucose-lowering therapy, 0.56 (95% CI, 0.41-0.77), and for both, 0.51 (95% CI, 0.34-0.76). These effects were also consistently seen in several subgroups examined.

CONCLUSIONS

Ramipril is associated with lower rates of new diagnosis of diabetes in high-risk individuals. Because these results have important clinical and public health implications, this hypothesis requires prospective confirmation.

Effect of atorvastatin on LDL oxidation and antioxidants in normocholesterolemic type 2 diabetic patients

BACKGROUND

Oxidative stress in diabetes increases lipid peroxidation, which stimulates the development of atherosclerosis.

METHODS

We investigated in a 3-month placebo-controlled study with 19 normocholesterolemic type 2 diabetic patients whether treatment with 10-mg atorvastatin influenced antioxidants and reduced LDL oxidizability, assessed by in vitro production of conjugated dienes after copper-induced LDL oxidation.

RESULTS

The lag phase, as a measure of the resistance of LDL to oxidation, did not change (62.8+/-8.2 respectively 59.6+/-9.7 min, p=n.s.), while conjugated dienes decreased (512+/-74 respectively 487+/-50 nmol, p=0.012). Plasma alpha-tocopherol and ubiquinol levels decreased, while their ratios to LDL cholesterol remained stable.

CONCLUSIONS

Atorvastatin favourably influences some parameters of LDL oxidation. Whether this effect is clinically relevant remains to be determined.

[Disorders of lipid metabolism in 3 patients with diabetes mellitus type 2]

Three patients with diabetes mellitus (type 2) and cardiovascular disease had disturbed lipid concentrations: two women aged 60 and 73 years and one man aged 47 years. The lipid levels were normalised during the 9-18 years of treatment with medication and in this period the patients experienced no cardiovascular events. Disturbances in plasma lipid levels play a major role in the increased risk of cardiovascular disease in patients with diabetes mellitus (type 2). Cholesterol-lowering treatment should be aggressive and based on the lipid profile. Statins reduce cardiovascular events by lowering the concentration of both the total cholesterol and low-density lipoprotein cholesterol whereas fibrates reduce cardiovascular events by increasing high-density lipoprotein cholesterol concentrations and lowering triglyceride concentrations.

Weight reduction and the impaired plasma-derived free fatty acid oxidation in type 2 diabetic subjects

In a previous study the oxidation of plasma free fatty acids (FFA) under baseline conditions and during exercise was lower in type 2 diabetic subjects compared with weight-matched controls. The present study intended to investigate the effect of weight reduction (very low calorie diet) on plasma FFA oxidation in seven type 2 diabetic male subjects (body fat, 37.4 +/- 1.2%; age, 51.3 +/- 3.4 yr; plasma glucose, 7.45 +/- 0.48 mmol/L). Subjects underwent a 10-week diet period. Body composition and substrate utilization during rest and during bicycle exercise (50% of maximum aerobic capacity) were determined before and after the diet (during weight-stable conditions). FFA metabolism was studied by means of the tracer [U-(13)C]palmitate. Rates of oxidation of plasma FFA were corrected with an acetate recovery factor. Additionally, activities of mitochondrial enzymes and cytosolic fatty acid-binding protein were determined in biopsies from the vastus lateralis muscle before and after the diet. The very low calorie diet resulted in a weight loss of 15.3 kg (110.8 +/- 7.4 vs. 95.5 +/- 5.8 kg; P < 0.01). The basal rates of appearance and disappearance of FFA decreased as a result of diet. The rates of appearance and disappearance of FFA during exercise were not different before and after diet. The oxidation of plasma-derived fatty acids tended to decrease after diet during baseline conditions (P = 0.10), whereas the plasma FFA oxidation during exercise was not different before and after the diet (14.1 +/- 1.9 vs. 14.8 +/- 1.8 micromol/kg fat-free mass.min). Skeletal muscle cytosolic fatty acid-binding protein and the activities of muscle oxidative enzymes did not significantly change as a result of weight loss. In conclusion, considerable weight reduction did not significantly improve plasma-derived FFA oxidation under baseline conditions and during exercise, suggesting that this impairment reflects a primary defect leading to the development of type 2 diabetes mellitus rather than resulting from the type 2 diabetic state.

Rosiglitazone

Type 2 diabetes mellitus is characterised by impaired insulin secretion, diminished peripheral insulin action and increased hepatic glucose production. Clinical trials have indicated that near-normal glucose control may reduce the risk for microvascular and - to a lesser extent - macrovascular complications in Type 2 diabetic patients. Thiazolidinediones improve insulin action by activating a nuclear receptor, PPARgamma. Therefore, these drugs are often referred to as 'insulin sensitisers'. Rosiglitazone is the second compound of this group. Clinical studies with rosiglitazone have shown that it is effective in lowering blood glucose levels in Type 2 diabetic patients treated with either diet alone, sulphonylurea or metformin. Preliminary studies suggest that rosiglitazone also improves glycaemic control in insulin-treated patients while even slightly decreasing insulin dose. The magnitude of the effects is, however, moderate. In diet-treated patients, the reduction of HbA1c levels amounted on average 0.5 - 1.5% and addition to existing sulphonylurea therapy decreased HbA1c by 1.0 - 1.2%. The clinical relevance of additional beneficial effects, i.e., on blood pressure and microalbuminuria, needs to be determined further. Rosiglitazone does not cause hypoglycaemia or gastrointestinal side effects. There is however some concern related to fluid retention, which seems to be an effect of all PPARgamma agonists. In patients treated with rosiglitazone, no severe hepatotoxic side effects have been noticed until now. In the treatment of our patients with Type 2 diabetes, drugs like rosiglitazone which directly reduce insulin resistance are very welcome but more data on its combined use with insulin are needed. Additional studies will also explore its long-term effects in sparing beta-cell function and reducing diabetes-related complications and atherosclerosis.

Diabetic ketoacidosis in a patient with acromegaly

Abnormalities of glucose metabolism are a common feature of acromegaly. Overt diabetes mellitus develops in about 10-15% of patients. We present an unusual complication of acromegaly: a 37-year old man with a 2-year history of acromegaly developed diabetic ketoacidosis 3 weeks after transsphenoidal adenomectomy. No specific cause for this sudden metabolic derangement could be demonstrated. Insulin need was very high in the first days after the onset of ketoacidosis, but was considerably reduced after initiation of treatment with octreotide and after successful re-operation.

The ADDITION study: proposed trial of the cost-effectiveness of an intensive multifactorial intervention on morbidity and mortality among people with Type 2 diabetes detected by screening

OBJECTIVE

The overall aims of the ADDITION study are to evaluate whether screening for prevalent undiagnosed Type 2 diabetes is feasible, and whether subsequent optimised intensive treatment of diabetes, and associated risk factors, is feasible and beneficial.

DESIGN

Population-based screening in three European countries followed by an open, randomised controlled trial.

SUBJECTS AND METHODS

People aged 40-69 y in the community, without known diabetes, will be offered a random capillary blood glucose screening test by their primary care physicians, followed, if equal to or greater than 5.5 mmol/l, by fasting and 2-h post-glucose-challenge blood glucose measurements. Three thousand newly diagnosed patients will subsequently receive conventional treatment (according to current national guidelines) or intensive multifactorial treatment (lifestyle advice, prescription of aspirin and ACE-inhibitors, in addition to protocol-driven tight control of blood glucose, blood pressure and cholesterol). Patients allocated to intensive treatment will be further randomised to centre-specific interventions to motivate adherence to lifestyle changes and medication. Duration of follow-up is planned for 5 y. Endpoints will include mortality, macrovascular and microvascular complications, patient health status and satisfaction, process-of-care indicators and costs.

Plasma FFA utilization and fatty acid-binding protein content are diminished in type 2 diabetic muscle

In this study, we investigated the hypothesis that impairments in forearm skeletal muscle free fatty acid (FFA) metabolism are present in patients with type 2 diabetes both in the overnight fasted state and during beta-adrenergic stimulation. Eight obese subjects with type 2 diabetes and eight nonobese controls (Con) were studied using the forearm balance technique and indirect calorimetry during infusion of the stable isotope tracer [U-(13)C]palmitate after an overnight fast and during infusion of the nonselective beta-agonist isoprenaline (Iso, 20 ng. kg lean body mass(-1) x min(-1)). Additionally, activities of mitochondrial enzymes and of cytoplasmatic fatty acid-binding protein (FABP) were determined in biopsies from the vastus lateralis muscle. Both during fasting and Iso infusion, the tracer balance data showed that forearm muscle FFA uptake (Con vs. type 2: fast 449+/-69 vs. 258 +/-42 and Iso 715+/-129 vs. 398+/-70 nmol. 100 ml tissue(-1) x min(-1), P<0.05) and FFA release were lower in type 2 diabetes compared with Con. Also, the oxidation of plasma FFA by skeletal muscle was blunted during Iso infusion in type 2 diabetes (Con vs. type 2: Iso 446 +/- 274 vs. 16+/-70 nmol. 100 ml tissue(-1) x min(-1), P<0.05). The net forearm glycerol release was increased in type 2 diabetic subjects (P< 0.05), which points to an increased forearm lipolysis. Additionally, skeletal muscle cytoplasmatic FABP content and the activity of muscle oxidative enzymes were lowered in type 2 diabetes. We conclude that the uptake and oxidation of plasma FFA are impaired in the forearm muscles of type 2 diabetic subjects in the overnight fasted state with and without Iso stimulation.

Does the risk of childhood diabetes mellitus require revision of the guideline values for nitrate in drinking water?

In recent years, several studies have addressed a possible relationship between nitrate exposure and childhood type 1 insulin-dependent diabetes mellitus. The present ecologic study describes a possible relation between the incidence of type 1 diabetes and nitrate levels in drinking water in The Netherlands, and evaluates whether the World Health Organization and the European Commission standard for nitrate in drinking water (50 mg/L) is adequate to prevent risk of this disease. During 1993-1995 in The Netherlands, 1,104 cases of type 1 diabetes were diagnosed in children 0-14 years of age. We were able to use 1,064 of these cases in a total of 2,829,020 children in this analysis. We classified mean nitrate levels in drinking water in 3,932 postal code areas in The Netherlands in 1991-1995 into two exposure categories. One category was based on equal numbers of children exposed to different nitrate levels (0.25-2.08, 2.10-6.42, and 6.44-41.19 mg/L nitrate); the other was based on cut-off values of 10 and 25 mg/L nitrate. We determined standardized incidence ratios (SIRs) for type 1 diabetes in subgroups of the 2,829,020 children with respect to both nitrate exposure categories, sex, and age and as compared in univariate analysis using the chi-square test for trend. We compared the incidence rate ratios (IRRs) by multivariate analysis in a Poisson regression model. We found an effect of increasing age of the children on incidence of type 1 diabetes, but we did not find an effect of sex or of nitrate concentration in drinking water using the two exposure categories. For nitrate levels > 25 mg/L, an increased SIR and an increased IRR of 1.46 were observed; however, this increase was not statistically significant, probably because of the small number of cases (15 of 1,064). We concluded that there is no convincing evidence that nitrate in drinking water at current exposure levels is a risk factor for childhood type 1 diabetes mellitus in The Netherlands, although a threshold value > 25 mg/L for the occurrence of this disease can not be excluded.

Pitfall of the accessory spleen

Two patients, one with insulinoma and one with Cushing's syndrome, are presented. Biochemical evaluation readily suggested the correct diagnosis. During radiologic imaging, the anatomic abnormality giving rise to these diseases, i.e. a pancreatic islet cell tumor, and an adrenal adenoma, at first were mistakenly interpreted as an accessory spleen on the basis of specific computed tomography and magnetic resonance imaging appearances. The insulinoma was identified as such during laparotomy, whereas additional jodo-cholesterol scintigraphy revealed the real nature of the lesion in the patient with Cushing's syndrome. Both patients were operated successfully.

Addition of low-dose rosiglitazone to sulphonylurea therapy improves glycaemic control in Type 2 diabetic patients

AIMS

This study was designed to test the efficacy and safety of low-dose rosiglitazone, a potent, insulin-sensitizing thiazolidinedione, in combination with sulphonylurea in Type 2 diabetic patients.

METHODS

For the intention-to-treat analysis, 574 patients (59% male, mean age 61 years) were available, randomized to receive 26 weeks of twice-daily placebo (n = 192), rosiglitazone 1 mg (n = 199) or rosiglitazone 2 mg (n = 183) in addition to existing sulphonylurea treatment with gliclazide (47.6% of patients), glibenclamide (41.8%) or glipizide (9.4%) (two patients were taking carbutamide or glimepiride). Change in haemoglobin A1c (HbA1c), fasting plasma glucose (FPG), fructosamine, insulin, C-peptide, albumin, and lipids were measured, and safety was evaluated.

RESULTS

Mean baseline HbA1c was 9.2% and FPG was 11.4 mmol/l. Rosiglitazone at doses of 1 and 2 mg b.d. plus sulphonylurea produced significant decreases, compared with sulphonylurea plus placebo, in HbA1c (-0.59% and -1.03%, respectively; both P<0.0001) and FPG (1.35 mmol/l and 2.44 mmol/l, respectively; both P<0.0001). Both HDL-cholesterol and LDL-cholesterol increased and potentially beneficial decreases in non-esterified fatty acids and gamma glutamyl transpeptidase levels were seen in both rosiglitazone groups. The overall incidence of adverse experiences was similar in all three treatment groups, with no significant cardiac events, hypoglycaemia or hepatotoxicity.

CONCLUSIONS

Overall, the combination of rosiglitazone and a sulphonylurea was safe, well tolerated and effective in patients with Type 2 diabetes.

The use of sulphonylureas in the elderly

Type 2 diabetes mellitus is a heterogeneous disorder characterised by defects in insulin secretion as well as reduced insulin action. During aging, glucose intolerance will gradually develop, and this is manifested primarily by an increase in the postprandial blood glucose response while fasting blood glucose levels are often less elevated. Abnormal beta-cell secretion of insulin is a main feature of this. Treatment of elderly patients with type 2 diabetes mellitus focuses on reduction of (hyperglycaemic) complaints and prevention of the development or progression of secondary complications. Although regular physical activity and dietary measures, aiming at bodyweight normalisation, are the cornerstones of therapy, pharmacological treatment with oral blood glucose lowering-agents often proves necessary to control the hyperglycaemia. In the United Kingdom Prospective Diabetes Study (UKPDS) it was clearly shown that patients with type 2 diabetes mellitus who were intensively treated with oral blood glucose-lowering agents or insulin developed less microvascular complications. The question whether achievement of strict metabolic control is also of benefit in elderly patients, is still unanswered. Sulphonylureas are drugs which stimulate insulin secretion by enhancing the release of insulin from the pancreatic beta-cells without an effect on insulin synthesis. They are frequently used in the treatment of type 2 diabetes mellitus, and several preparations are available. In general, there are no major differences in effectiveness between the various sulphonylureas. Long term treatment with sulphonylureas will decrease fasting and postprandial plasma glucose levels by 3 to 5 mmol/L, and glycosylated haemoglobin by 20%. However, after its initial decline, plasma glucose level will often go up slightly during the following months to years. Sulphonylureas are usually well tolerated. Hypoglycaemia is the most frequently occurring adverse effect, which may be very serious and damaging in the elderly. It has been associated primarily with long-acting sulphonylureas, like chlorpropamide and glibenclamide (glyburide). Hypoglycaemic episodes may trigger serious events like myocardial infarction or stroke. Therefore, shorter-acting compounds like tolbutamide and gliclazide have been relatively well tolerated and appear to be the best choice to treat elderly patients. It is advisable to start with a low dose and increase the dose, when needed, in small steps. The efficacy of sulphonylureas is much greater when they are taken before a meal. Because of the fact that type 2 diabetes mellitus is a progressive disease, and residual beta-cell function decreases with time, insulin therapy may ultimately be warranted in a significant number of patients.

Repaglinide--a new compound for the treatment of patients with type 2 diabetes

Repaglinide is a new oral blood glucose lowering agent, a member of the carbamoylmethyl benzoic acid (CMBA) family. Its mechanism of action is partly similar to that of the sulphonylurea: the release of insulin from the pancreatic beta cells is stimulated by closure of ATP-dependent potassium channels. However, repaglinide regulates these channels via a different binding site on the beta cell than glibenclamide, and the drug does not cause insulin release in the absence of glucose, or during voltage-clamping. After oral administration the drug is rapidly absorbed and eliminated. It is therefore used in a meal-related dosing regimen; repaglinide is taken with each main meal. This meal-related use may give a more physiological mimick of daytime insulin requirement than once-daily or twice-daily use of sulphonylurea. Patients using repaglinide are less likely to develop hypoglycaemic symptoms when they miss or postpone a meal in comparison with patients on glibenclamide treatment. In long-term comparative phase 3 clinical studies it was found that repaglinide is equally effective in maintaining glycaemic control as existing sulphonylurea, but it gives significantly better control of postprandial blood glucose levels. Repaglinide can be used as monotherapy both in obese and non-obese type 2 diabetic patients, and is also very effective in combination with drugs like metformin or thiazolidines. Because of its excretion through liver and bile it is also an attractive drug for diabetic patients with diminished kidney function, especially the elderly diabetic. Although the overall incidence of hypoglycaemia was similar during use of repaglinide and of sulphonylurea, fewer serious hypoglycaemic episodes were observed in repaglinide-treated patients.

Miglitol, a new alpha-glucosidase inhibitor

Miglitol (Bay m 1099, Bayer) is a second generation alpha-glucosidase inhibitor. It is a derivative of 1-desoxynojirimycin, and binds reversibly to the brushborder alpha-glucosidase enzymes. In contrast to its parent drug (acarbose, Bay g 5421, Bayer), miglitol is almost completely absorbed in the small intestine. It has to be taken with each main meal, and through its effect on carbohydrate digestion it blunts the postprandial blood glucose increase. Miglitol has no or a very small effect on fasting blood glucose levels. The blood-glucose lowering effects of miglitol in patients with Type 2 diabetes are lower than those of the frequently-used sulphonylurea compounds. Long-term studies show that a moderate average reduction of HbA1c of 0.3-0.7% point from baseline can be achieved. An advantage over sulphonylurea is the effect on serum insulin levels: miglitol therapy leads to slightly lower postprandial levels of serum insulin, whereas chronic sulphonylurea treatment usually increases serum insulin levels. This insulin-sparing effect may, in theory, lead to a lesser weight gain or even no weight gain and reduced risk of hypoglycaemia during chronic treatment. Long-term experience in Type 1 diabetic patients is limited. Similarly, miglitol may lead to reduced postprandial glucose excursions, slightly reduced insulin requirements and perhaps, as a consequence, a lower risk of hypoglycaemia. More long-term data are needed to fully assess to the clinical use of miglitol in these patients.

Microdialysis assessment of local adipose tissue lipolysis during beta-adrenergic stimulation in upper-body-obese subjects with type II diabetes

The present study was designed to investigate indicators of abdominal adipose tissue lipolysis (microdialysis), and subcutaneous adipose tissue blood flow and whole-body lipolysis, in obesity-associated type II diabetes during overnight-fasted conditions (baseline) and during intravenous infusion of the non-selective beta-agonist isoprenaline. Basal subcutaneous adipose tissue blood flow and isoprenaline-induced increases in adipose tissue blood flow were not significantly different between subjects with type II diabetes and non-obese, non-diabetic controls. Adipose tissue interstitial glycerol concentrations were significantly higher in subjects with type II diabetes compared with controls (P<0. 01), and during isoprenaline infusion there was a decrease in interstitial glycerol in both groups (P<0.001). Arterial glycerol concentrations were higher in subjects with type II diabetes compared with controls (P<0.05), whereas the increases in arterial glycerol concentration in response to isoprenaline infusion were of a similar magnitude in the two groups. Estimated subcutaneous adipose tissue glycerol release was not significantly different between the groups (controls and subjects with type II diabetes: baseline, -129+/-32 and -97+/-72 micromol.min(-1).100 g(-1) adipose tissue respectively; isoprenaline, -231+/-76 and -286+/-98 micromol. min(-1).100 g(-1) respectively). Values for fat oxidation were not significantly different between groups, whereas the isoprenaline-induced increase in fat oxidation tended to be less pronounced in subjects with type II diabetes compared with controls (0.022+/-0.008 and 0.038+/-0.003 g/min respectively; P=0.058). Thus estimated basal subcutaneous adipose tissue glycerol release, expressed per unit of fat mass, is not different in controls and in subjects with type II diabetes. Additionally, the isoprenaline-induced increases in indicators of local abdominal subcutaneous adipose tissue, systemic lipolysis and abdominal adipose tissue blood flow responses were comparable in obese subjects with type II diabetes and in controls. The last two findings contrast with previous data from obese subjects, indicating that the regulation of lipolysis may differ in obesity and obesity-associated type II diabetes.

[Glycemic regulation and management of essential hypertension in diabetics with type 2 diabetes mellitus; the 'United Kingdom prospective diabetes study' of diabetic complications]

Patients with type 2 diabetes mellitus often develop micro- and macrovascular complications. In 25% of them, complications are already present at the time of diagnosis. The principal objective of the United Kingdom prospective diabetes study was to determine if good blood glucose control and adequate treatment of hypertension in patients with type 2 diabetes mellitus can prevent development of diabetes-related complications. The question was also studied if they way in which this blood glucose control was achieved and the way of treating the blood pressure affected the prognosis. Blood glucose control was found to reduce the incidence of--especially--microvascular complications. Oral hypoglycaemic agents and insulin both play an important part in achieving good control. Treatment with metformin reduced mortality due to cardiovascular disease in obese patients. Strict control of the blood pressure reduced development of micro- and macrovascular complications; the mortality from diabetes-related disorders and the numbers of patients suffering a stroke or heart failure. Non of the antihypertensive drugs used (an ACE inhibitor and a beta-blocking agent) offered any advantages over the other.

Endothelium-dependent vasodilatation, plasma markers of endothelial function, and adrenergic vasoconstrictor responses in type 1 diabetes under near-normoglycemic conditions

It is unknown whether and to what extent changes in various endothelial functions and adrenergic responsiveness are related to the development of microvascular complications in type 1 diabetes. Therefore, endothelium-dependent and endothelium-independent vasodilatation, endothelium-dependent hemostatic factors, and one and two adrenergic vasoconstrictor responses were determined in type 1 patients with and without microvascular complications. A total of 34 patients with type 1 diabetes were studied under euglycemic conditions on two occasions (11 without microangiopathy, 10 with proliferative and preproliferative retinopathy previously treated by laser coagulation, 13 with microalbuminuria, and 12 healthy volunteers also were studied). Forearm vascular responses to brachial artery infusions of N(G)-monomethyl-L-arginine (L-NMMA), sodium nitroprusside, acetylcholine (ACh), clonidine, and phenylephrine were determined. The ACh infusions were repeated during coinfusion of L-arginine. Furthermore, plasminogen activator inhibitor type 1 (PAI-1) activity, tissue plasminogen activator antigen levels, von Willebrand factor antigen levels, tissue factor pathway inhibitor (TFPI) activity, and endothelin-1 levels were measured. No differences in endothelium-dependent or endothelium-independent vasodilatation or adrenergic constriction were observed between the diabetic patients and the healthy volunteers. In comparison to the first ACh infusion, the maximal response to repeated ACh during L-arginine administration was reduced in the diabetic patients, except in the patients with proliferative and preproliferative retinopathy previously treated by laser coagulation. In these patients, the combined infusion of L-arginine and ACh resulted in an enhanced response. TFPI activity was elevated, and PAI-1 activity was reduced in the type 1 diabetic patients. Furthermore, PAI-1 activity was positively correlated with urinary albumin excretion (r = 0.48, P < 0.01) and inversely correlated with the vasodilatory response to the highest ACh dose (r = -0.37, P < 0.05). The response to the highest ACh and L-NMMA dose were positively correlated with mean arterial blood pressure (r = 0.32, P < 0.01; r = 0.41, P < 0.01, respectively). Forearm endothelium-dependent and endothelium-independent vasodilatation and adrenergic responsiveness were unaltered in type 1 diabetic patients with and without microvascular complications. Relative to healthy control subjects, endothelium-dependent vasodilatation was depressed during a repeated ACh challenge (with L-arginine coinfusion) in the diabetic patients without complications or with microalbuminuria. In contrast, this vasodilatation was enhanced in the patients with retinopathy. Elevation of TFPI was the most consistent marker of endothelial damage of all the endothelial markers measured.

Mechanical properties of mesenteric arteries in diabetic rats: consequences of outward remodeling

Diabetes induces hemodynamic and biochemical changes that can influence mechanical properties of arteries. Structure and mechanics of mesenteric small arteries were investigated in rats with streptozotocin-induced diabetes (duration 7-9 wk). The external diameter of mesenteric artery branches was measured in control (n = 9) and diabetic (n = 7) Wistar Rp rats at baseline and during pressurization in situ (0-150 mmHg) under normal and passive smooth muscle conditions. Mean arterial pressure and mesenteric artery pressure were not significantly different. Baseline mesenteric artery diameter was larger in the diabetes-induced group (439 +/- 12 vs. 388 +/- 18 micrometers, P < 0.05). Media cross-sectional area of arteries from diabetic rats was not significantly increased (0.0149 +/- 0.0015 vs. 0.0122 +/- 0.0007 mm2). Cross-sectional compliance was significantly increased in diabetic rats at intraluminal pressures ranging from 25 to 75 mmHg (P < 0.005), whereas cross-sectional distensibility was not modified. Wall tension and circumferential wall stress were increased in diabetes. These results indicate that mesenteric small arteries of diabetic rats display eutrophic outward remodeling associated with increased wall tension and circumferential wall stress.

Substrate utilization and thermogenic responses to beta-adrenergic stimulation in obese subjects with NIDDM

OBJECTIVE

This study intended to investigate disturbances in beta-adrenergically-mediated substrate utilization and thermogenesis in obese subjects with mild non insulin-dependent diabetes mellitus (NIDDM).

DESIGN

Following a baseline period of 30 min, the beta-agonist isoproterenol (ISO) was administered in increasing doses of 6, 12, and 24 ng/kgFFM x min, each dose for 30 min.

SUBJECTS

Nine healthy lean males (CON, 50.6+/-2.4 y, % body fat: 16.0+/-1.8) and 10 obese subjects with NIDDM (51.8+/-2.4 y, % body fat 34.1+/-1.9).

RESULTS

Basal non esterified fatty acid concentrations (NEFA) and basal fat oxidation (absolute or expressed per unit fat free mass, FFM) were significantly higher in NIDDM as compared to CON, whereas basal carbohydrate (CHO) oxidation was significantly lower. The ISO-induced increase in NEFA-concentrations was blunted in NIDDM (delta at 24 ng/kgFFM x min: CON: 717+/-59 micromol/l vs NIDDM: 358+/-97 micromol/l, P< 0.01). The non-protein respiratory exchange ratio (RER) did not change in NIDDM and significantly decreased in CON during ISO-infusion (P < 0.05), reflecting the tendency towards a blunted increase in fat oxidation in NIDDM (delta fat ox at 24 ng; CON: 0.025+/-0.005 g/min vs NIDDM 0.016+/-0.007 g/min). The ISO-induced thermogenic response was comparable in NIDDM and CON (at 24 ng %increase above baseline: CON: 16.8+/-2.2% vs NIDDM: 14.7+/-0.9%). At all time points, there were no significant differences in circulating ISO and noradrenaline concentrations. Basal adrenaline (A) concentrations and A concentrations during ISO-infusion were significantly lower in NIDDM (basal A; CON: 64+/-15 pg/ml vs NIDDM: 25+/-2 pg/ml, P < 0.001).

CONCLUSION

There appear to be deviations in beta-adrenoceptor mediated fat utilization and adrenal medulla function in obesity-associated NIDDM. The impairments in sympathetically mediated fat utilization have previously been observed in 'simple' obese subjects, indicating that these disturbances are confined to the obese state per se.

A 1-year multicenter randomized double-blind comparison of repaglinide and glyburide for the treatment of type 2 diabetes. Dutch and German Repaglinide Study Group

OBJECTIVE

Repaglinide is a newly developed oral blood glucose-lowering agent that exerts its effect by stimulating insulin secretion. This multicenter study was designed to compare the efficacy and safety of this drug with glyburide in a 1-year randomized double-blind study of outpatients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 424 subjects (154 women, 270 men) participated and had the following characteristics: age, 61 +/- 9 years; duration of diabetes. 8 years (range 0.5-35); BMI, 28.3 +/- 3.5 kg/m2; HbA1c, 7.1 +/- 1.4%; and fasting plasma glucose, 10.8 +/- 3.1 mmol/l. The majority of the subjects (91%) were previously treated with sulfonylurea, alone or in combination with metformin. The patients were randomized to a 2:1 ratio of repaglinide (0.5-4 mg t.i.d.) or glyburide (1.75-10.5 mg daily) treatment. The study protocol included a screening visit to assess patient eligibility; a titration period of 6-8 weeks, during which the dosages of repaglinide and glyburide were optimized; and a subsequent 12-month treatment period on fixed, optimal dosages.

RESULTS

The trial was completed by 320 subjects, 211 (74%) in the repaglinide and 109 (78%) in the glyburide group. HbA1c initially decreased in both groups and then increased during the second half-year of the maintenance period to a similar extent in the repaglinide and glyburide subjects (0.58 and 0.45% vs. at screening, respectively). In the small group of subjects who previously controlled their condition with diet only (n = 37), a sustained improvement of metabolic control could be observed with both drugs, which was slightly better with glyburide than with repaglinide (theta HbA1c -2.4 vs. -1.0%; P < 0.05). The same trends were seen with fasting plasma glucose. There were no changes in serum lipids. Over the course of the study, 15% of the repaglinide-treated and 13% of glyburide-treated subjects withdrew due to adverse events, mostly hyperglycemia. No differences in adverse events between both drugs were reported. There were no differences in incidences of hypoglycemia.

CONCLUSIONS

Repaglinide is a safe and efficacious oral blood glucose-lowering agent, with a potency similar to that of glyburide. Its rapid onset of action and hepatic clearance allows meal-related administration, including in subjects with impaired kidney function.

Prognostic factors for successful insulin therapy in subjects with type 2 diabetes

OBJECTIVE

To assess which factors influence or predict the efficacy of insulin therapy in subjects with type 2 diabetes, who were poorly controlled despite maximal doses of oral glucose lowering agents.

RESEARCH DESIGN AND METHODS

Seventy-five patients with type 2 diabetes participated (mean age (+/- SD), 67 +/- 8 years; body mass index, 25.8 +/- 5.0 kg/m2; median time since diagnosis of diabetes, 8 years (range 1-36); 27 males and 48 females). They were transferred to insulin therapy, in which case either insulin alone, or a combination of insulin and glibenclamide was employed. The importance of baseline parameters (glycaemic control, beta-cell function, measures of insulin resistance) was assessed by comparing good and poor responders (defined as achieved HbA1c < 8.0 or > 9.0%) to insulin therapy, and by multiple logistic regression analysis of these baseline parameters and achieved metabolic control.

RESULTS

During insulin therapy, HbA1c levels decreased from 10.9 +/- 1.3 to 8.2 +/- 1.1% (p < 0.001), and fasting blood glucose levels decreased from 14.0 +/- 2.3 to 8.2 +/- 2.1 mmol/l (p < 0.001). Thirty patients reached HbA1c levels < 8.0%, 21 of them even < 7.5%. The mean increase in body weight was 4.5 kg. HbA1c after 6 months was 7.0 +/- 0.6% in the good responders, and 9.8 +/- 0.6% in the poor responders (p < 0.001), despite a comparable insulin dose. Baseline metabolic control was similar in both groups. Also, glucagon-stimulated and calculated insulin secretion, as well as parameters of insulin resistance, such as fasting serum insulin levels, free fatty acids, and serum triglycerides, were not different between both groups, and certainly not higher in the poor responders. Also previous metformin use was not different. However, poor responders were more obese than good responders, and had significantly longer known duration of diabetes. Multiple logistic regression confirmed that only duration of diabetes and body mass index were independent predictors of response to insulin therapy.

CONCLUSIONS

We conclude that in elderly patients with type 2 diabetes improvement of glycaemic control can be achieved at the expense of some weight gain. Measurement of residual insulin secretion prior to institution of insulin treatment does not discriminate between good and poor responders to this model of therapy. Especially in obese patients with longer duration of diabetes more attention is needed in order to achieve optimal glycaemic control. Combination of insulin with newer drugs, like thiazolidinediones, may perhaps achieve this.

Cytochrome P450, peroxisome proliferation, and cytoplasmic fatty acid-binding protein content in liver, heart and kidney of the diabetic rat

Diabetes mellitus generally results in an increased systemic fatty acid mobilization which can be associated with an increase in mitochondrial and peroxisomal beta-oxidation of fatty acids in selected tissues. The latter is usually accompanied by a concomitant increase in the tissue content of cytoplasmic fatty acid-binding protein (FABP) which functions in the intracellular translocation of fatty acids. It was previously found that in liver clofibrate-induced proliferation of peroxisomes and increase in FABP expression each are dependent on the induction by cytochrome P4504A1 -mediated (CYP4A1) formation of dicarboxylic acids. We studied whether peroxisome proliferation and an increase of FABP contents in liver, heart and kidney of streptozotocin-induced diabetic rats are also accompanied by an increase of CYP4A1 activity, as this would indicate a possible regulatory role for dicarboxylic acids in peroxisome proliferation and FABP induction in diabetic organs other than liver. In livers of the diabetic rat, a concomitant increase was observed of the activities of CYP4A1 and the peroxisomal key enzyme fatty acyl-CoA oxidase (FACO) and of the FABP content. In the diabetic heart FACO activity and FABP content also increased, but there was no induction of CYP4A1 activity. Conversely, in diabetic kidney there was no increase in FACO activity nor FABP content in spite of a marked induction of CYP4A1 activity. It is concluded that streptozotocin-induced diabetes leads to increased peroxisome proliferation and increased levels of FABP in both liver and heart, which only in liver is accompanied by an induction of the cytochrome P450 system. Consequently, it is not likely that dicarboxylic acids are involved in the induction of peroxisome proliferation in the heart.

Effects of acarbose (Glucobay) in persons with type 1 diabetes: a multicentre study

The aim of this multicentre study was to investigate the effect--in everyday life--of long term administration of acarbose on parameters of glycaemic control, daily insulin requirements, lipid parameters and tolerability in ambulant type 1 diabetic subjects insufficiently controlled with diet and insulin. Furthermore, effects on lipid parameters were to be studied. A total of 16 patients withdrew from the study, 13 of these during the acarbose medication period. For four of these 13 patients the adverse event started during the placebo run-in period. The data of 62 patients (35 men and 27 women, mean age 38 (range 18-64) years, median duration of diabetes 10 (range 1-40) years) were valid for statistical analysis. The median daily dose of acarbose at the final assessment (i.e. after 16 weeks of active treatment) was 200 (range 75-300) mg. During the placebo run-in period HbA1c levels tended to decrease from 8.9 +/- 1.1 to 8.5 +/- 0.9%. After 8 and 16 weeks of acarbose treatment the mean level had decreased further to 8.1 +/- 0.9 and 8.2 +/- 0.9%, respectively (both P < 0.001). After stopping acarbose HbA1c levels increased again to a mean level of 8.6 +/- 0.9%. Mean levels of HbA1c per centre followed the same profile. Seven-point blood glucose profiles followed the same pattern. None of these changes over time reached statistical significance except for a significant drop during acarbose treatment of the time-point 90 min after lunch (P < 0.01). After stopping acarbose treatment values returned to pre-study levels. For total cholesterol, HDL-cholesterol, triglycerides, Apo A1 and Apo B, and Lp(a) no significant changes were observed. Daily insulin dose was 48 (range 26-92) U at the start of the study and did not change. The most frequent reported adverse events were flatulence (43%), diarrhoea (27%), and abdominal pain (11%). We conclude that acarbose up to 3 x 100 mg/day can be a valuable adjunct to insulin in improving metabolic control in persons with type 1 diabetes.

Lipid peroxidation in type 2 diabetes: relationship with macrovascular disease?

BACKGROUND

Macrovascular disease is the leading cause of death in diabetes. The increased risk of atherosclerosis in diabetes may be partly explained by increased lipid peroxidation.

METHODS

We assessed lipid peroxidation in subjects with type 2 diabetes with (n = 23) and without (n = 23) macrovascular complications versus healthy age-matched controls (n = 13). The diabetic groups were matched for glycemic control (mean HbA1c = 9%), and for age had similar known duration of diabetes.

RESULTS

Plasma TBARS were comparable between diabetic subjects with and without macrovascular complications (1.89 +/- 0.32 and 1.81 +/- 0.28 mumol/l) and elevated compared to healthy controls (1.64 +/- 0.26 mumol/l, p = 0.025). Ratios of IgG and IgM antibodies to oxidized vs. native LDL were comparable between diabetic subjects and controls, and also between diabetic subjects with or without macrovascular complications. The lag phase, an index of the resistance of LDL to oxidation, was significantly longer in diabetic patients with macrovascular complications (66 +/- 8 min) vs. those without macrovascular complications and controls (resp. 59 +/- 7 and 56 +/- 7 min, p < 0.05). An explanation may be the frequent use of drugs with possible antioxidant potential, e.g. beta-blocking agents, ACE-inhibitors and calcium entry blockers by these patients. Surprisingly, plasma vitamin E levels were higher in diabetic subjects.

CONCLUSIONS

We found no evidence of increased lipid peroxidation in diabetic subjects with macrovascular complications, but an increased resistance to oxidation in this group, probably due to an altered antioxidant status. The increased TBARS level in diabetic subjects contrasts with the other indices of lipid peroxidation and may be related to prevalent hyperglycemia and should therefore be interpreted cautiously.

Consequences of long-term hyperparathyroidism

We describe a young woman with long-term untreated hyperparathyroidism with a superimposed vitamin D deficiency and an extremely decreased bone mineral density that was complicated by a vertebral fracture. Despite pretreatment with intravenous pamidronate and short-term vitamin D supplementation, severe and long-standing hypocalcaemia ('hungry bone syndrome') developed after parathyroidectomy. We discuss the consequences of hyperparathyroidism, especially the effects on bone, the complications of parathyroidectomy and the possibilities of preoperative treatment with bisphosphonates.

Arteriolar reactivity in conscious diabetic rats: influence of aminoguanidine treatment

The effect of 6 weeks' streptozotocin (STZ)-induced (70 mg/kg) diabetes and aminoguanidine (AG) treatment (50 mg/kg s.c. or 250-750 mg/l given in drinking water) on arteriolar reactivity to vasoactive substances was investigated in conscious rats. Studies were performed in untreated control rats (n = 13), STZ-induced diabetic rats (n = 11), AG-treated control rats (n = 12), and AG-treated diabetic rats (n = 12). Rats were provided with a dorsal microcirculatory chamber that allowed intravital microscopy of striated muscle arterioles of varying diameter (A1, large; A2, intermediate; and A3, small arterioles) in conscious animals. The mean arterial pressure (MAP) and arteriolar diameter responses to intravenous infusion of the following drugs were examined: the endothelium-dependent vasodilator acetylcholine (ACh; 3, 10, and 30 microg x kg(-1) x min(-1)), the potassium-channel opener levcromakalim (LC; 30 microg/kg), and the vasoconstrictor agents ANG II (0.1 and 0.3 microg x kg(-1) x min(-1)) and norepinephrine (NE; 0.2, 0.6, and 2.0 microg x kg(-1) x min(-1)). Baseline MAP was lower in both diabetic groups versus the nondiabetic groups (P < 0.05). AG treatment had no influence on baseline MAP. The absolute change in MAP after drug infusion tended to be lower in the diabetic rats than in their nondiabetic littermates. Arteriolar vasodilatory responses to ACh and LC were attenuated in the diabetic animals (1 +/- 7 vs. 19 +/- 7% [P < 0.05] and 7 +/- 3 vs. 34 +/- 8% [P < 0.01] in A2, respectively). AG treatment of diabetic animals did not prevent the development of this disturbance. Vasoconstrictor responses were not influenced by the diabetic state. In the intermediate arterioles of AG-treated control rats, a hyperresponse was observed after ANG II infusion (-10 +/- 2 vs. -2 +/- 2%; P < 0.05) and a hyporesponse was observed after ACh and LC infusion (2 +/- 3 and 15 +/- 6%, respectively; P < 0.05 vs. untreated control rats). These data indicate that 6 weeks of experimental diabetes is associated with a decreased endothelium-dependent and -independent vasodilatation. AG treatment had no beneficial effect on this disturbance.

Breakers of advanced glycation end products restore large artery properties in experimental diabetes

Glucose and other reducing sugars react with proteins by a nonenzymatic, posttranslational modification process called nonenzymatic glycation. The formation of advanced glycation end products (AGEs) on connective tissue and matrix components accounts largely for the increase in collagen crosslinking that accompanies normal aging and which occurs at an accelerated rate in diabetes, leading to an increase in arterial stiffness. A new class of AGE crosslink "breakers" reacts with and cleaves these covalent, AGE-derived protein crosslinks. Treatment of rats with streptozotocin-induced diabetes with the AGE-breaker ALT-711 for 1-3 weeks reversed the diabetes-induced increase of large artery stiffness as measured by systemic arterial compliance, aortic impedance, and carotid artery compliance and distensibility. These findings will have considerable implications for the treatment of patients with diabetes-related complications and aging.

Efficacy and safety of a new cholesterol synthesis inhibitor, atorvastatin, in comparison with simvastatin and pravastatin, in subjects with hypercholesterolemia

BACKGROUND

High levels of total and LDL-cholesterol are associated with an increased risk of atherosclerotic vascular disease. Lowering of serum cholesterol levels by pharmacologic intervention with inhibitors of cholesterol synthesis, the so-called statins, reduces the incidence of cardiovascular events in subjects with and without atherosclerotic manifestations. In a 16-week, multicenter, randomized, open-label cross-over study we compared the efficacy and safety of the new compound atorvastatin for reducing LDL-cholesterol with simvastatin or pravastatin.

METHODS

Following a 4-week placebo-controlled baseline period patients with LDL-cholesterol between 4.1 and 6.2 mmol/l and serum triglycerides below 3.4 mmol/l were randomly assigned to treatment either with 5 or 20 mg atorvastatin, or with 10 mg simvastatin or 20 mg pravastatin once daily for 4 weeks. After a placebo-washout period of 4-6 weeks, patients switched to the alternate treatment. At the end of weeks 3 and 4 of each study phase the serum concentrations of lipid parameters and apolipoproteins as well as safety parameters were determined.

RESULTS

A total of 78 subjects entered the study. Treatment with 5 mg atorvastatin reduced total and LDL-cholesterol by 21 and 27%, respectively, which was similar to 10 mg simvastatin (total cholesterol -20%, LDL-cholesterol -28%) and 20 mg pravastatin (-18 and -24%, respectively). The effects of this low dose of atorvastatin on triglyceride levels (-16%) was not different from that of simvastatin and pravastatin (-8 and -11%, respectively). Treatment with 20 mg atorvastatin caused significantly larger reductions in total cholesterol (-33%) and LDL-cholesterol (-44%), serum triglycerides (-23%), and apo B (-40%) compared to simvastatin and pravastatin. Atorvastatin was well-tolerated, and no serious or medically important adverse events were observed.

CONCLUSIONS

We conclude that atorvastatin is a safe and very efficacious cholesterol-lowering agent, which also possesses significant triglyceride-lowering properties.

Beneficial gamma-knife radiosurgery in a patient with Nelson's syndrome

A 50-year-old female patient with Cushing's disease had undergone transsphenoidal removal of the pituitary adenoma and conventional radiotherapy in 1988. Since no remission was achieved, she underwent bilateral adrenalectomy in May 1989. During out-patient follow-up, she developed signs and symptoms due to invasive Adrenocorticotrophic hormone (ACTH)-producing macroadenoma (Nelson's syndrome) in 1994. ACTH levels at that time were 3400 ng/l. Near-total surgical resection of a 2.0 x 2.5 pituitary tumour which slightly extended laterally into the cavernous sinus was achieved by subfrontal approach in June 1994. However, she rapidly developed a recurrence of her complaints, with a visual field defect inferior-nasal of the left eye, and a second operation was carried out in November 1994. Culture of the tumour's cells revealed significant inhibition of ACTH production by bromocriptine. Adjuvant treatment with this drug therefore was started in November 1994. Because of the rapid recurrence it was decided to treat her with gamma-knife radiosurgery. The dose that was given in January 1995 was 12 Gy to the border and 40 Gy into the centre of the tumour. During a follow-up of more than 2 years, no recurrence, but even a minor reduction of tumour mass was observed by magnetic resonance imaging (MRI). Plasma ACTH levels decreased gradually to levels between 200 and 400 ng/l, and ophthalmologic complaints disappeared. It is concluded that gamma-knife radiosurgery may be a good alternative for patients with Nelson's syndrome who have rapidly recurring disease.

[Short-acting insulin analogs]

Patients with diabetes mellitus type I usually are treated with a multiple injection regimen comprising rapid-acting insulin before meals and intermediate-acting insulin at bedtime. Recently, the rapid-acting insulin analogue insulin LISPRO was introduced on the Dutch market. This form of insulin is very rapidly taken up into the bloodstream from the subcutaneous tissue. The advantages of the use of insulin LISPRO are the comfort of injecting the insulin just before a meal, the more rapid correction of incidental hyperglycaemia and the slightly lower incidence of (nocturnal) hypoglycaemia in comparison with conventional rapid-acting insulin. There is no argument in favour of switching diabetics to insulin LISPRO if they are well-controlled with normal rapid-acting insulin and have few episodes of hypoglycaemia. In some persons the duration of action of insulin LISPRO may be too short, leading to preprandial hyperglycaemia. This can be avoided by using a second injection of intermediate-acting insulin, either before breakfast or before lunch.

Shock of unknown origin--think of mastocytosis!

Shock of unknown origin may be due to mastocytosis, in which excessive release of mast cell mediators can cause severe systemic vasodilation. We describe a patient who experienced two life-threatening episodes of shock which appeared to be due to mastocytosis. Therapeutic options are discussed.

Peripheral blood flow and noradrenaline responsiveness: the effect of physiological hyperinsulinemia

OBJECTIVE

Insulin seems to have vasodilator properties, but it is unclear if insulin in postprandial concentrations is a specific vasodilator of skeletal muscle resistance arterioles only or that various types of vessels are affected. The aim of the present study was to determine the direct effects and the time course of regional/local physiological hyperinsulinemia on skeletal muscle arterioles, skin blood flow and peripheral venous tone and the responsiveness of these different vascular beds to noradrenaline.

METHODS

In protocol I (n = 12) we infused insulin into the brachial artery for 180 min (3.5 mU/min) and evaluated the effects on forearm (muscle) blood flow (FBF) and skin blood flow (SBF). Furthermore, noradrenaline (0.025, 0.01 and 0.4 microgram/min) was infused (i.a.) at baseline, at 90 and 180 min after the start of insulin. In protocol 2 (n = 10) the same regional forearm hyperinsulinemia was achieved, but now the local venous responsiveness to noradrenaline (1.7-55 ng/min, at baseline and at 90 and 180 min) was measured in a dorsal hand vein. In protocol 3 we evaluated the local effects of different doses of insulin (1-100 mU/min) infused directly into hand veins preconstricted with phenylephrine.

RESULTS

Forearm hyperinsulinemia (approximately 50 mU/l) led to a significant increase in FBF after 180 min (median 26%, interq ranges 5-50, P < 0.05), while SBF was not altered. Forearm hyperinsulinemia did not affect the noradrenergic responsiveness in skeletal muscle or skin. Infused locally into hand veins only the highest dose of insulin (100 mU/min) caused a minor venodilation (7% [2.4-12.5], P < 0.05).

CONCLUSION

Regional forearm physiological hyperinsulinemia has a vasodilator effect on resistance vessels in skeletal muscle, but is slow in onset (180 min). However, skin vasculature and peripheral veins are not affected by this hyperinsulinemia.

Increased tissue factor pathway inhibitor (TFPI) and coagulation in patients with insulin-dependent diabetes mellitus

Recently, we found an increase in tissue factor pathway inhibitor (TFPI) activity in patients with insulin-dependent diabetes mellitus (IDDM). This increase in TFPI activity could be the result of increased thrombin formation and/or altered binding of TFPI to glycosaminoglycans. We studied TFPI activity (chromogenic assay) in relation to prothrombin F1 + 2 fragments and endogenous thrombin potential (ETP), in 46 IDDM patients, and 18 age and sex-matched healthy controls. Prothrombin, antithrombin and thrombomodulin were also determined. In IDDM patients, TFPI activity and F1 + 2 levels were significantly higher, while ETP, prothrombin antigen levels, and antithrombin activity were lower as compared to the controls. In IDDM patients with microalbuminuria, a manifestation of generalized angiopathy, TFPI activity, F1 + 2 and thrombomodulin levels were higher than in patients with only retinopathy or patients without complications. No correlation between TFPI activity, F1 + 2 levels and thrombomodulin was found, while TFPI activity was negatively correlated with ETP (r = -0.27). Microalbuminuria was significantly correlated with TFPI activity (r = 0.46), F1 + 2 (r = 0.56), and thrombomodulin (r = 0.52). In TFPI-depleted plasma, ETP increased, indicating that ETP is affected by TFPI. In conclusion, the increase in TFPI activity in IDDM patients may not be considered to be a reaction on a procoagulant state. It is hypothesized that vascular damage, leading to alterations in glycosaminoglycans, is in part responsible for the changes in TFPI activity, F1 + 2 levels and ETP.