Socioeconomic Position and Type 2 Diabetes: The Mediating Role of Psychosocial Work Environment- the Maastricht Study

Objective: We examined the association between low socioeconomic position (SEP) and Type 2 Diabetes Mellitus (T2DM), and the mediating role of psychosocial work environment by using counterfactual mediation analysis. Methods: Data from 8,090 participants of The Maastricht Study were analysed. SEP indicators (education, income, occupation), self-reported psychosocial work stressors, (pre)diabetes by oral glucose tolerance test were measured at baseline. Incident T2DM was self-reported per annum up to 9 years. Cox regression and causal mediation analyses were performed. Results: 2.8% (N = 172) of the participants without T2DM at baseline reported incident T2DM. People with lower SEP more often had prevalent T2DM (e.g., education OR = 2.49, 95% CI: 2.16-2.87) and incident T2DM (e.g., education HR = 2.21, 95% CI: 1.53-3.20) than higher SEP. Low job control was associated with prevalent T2DM (OR = 1.44 95% CI: 1.25-1.67). Job control partially explained the association between income and prevalent T2DM (7.23%). Job demand suppressed the associations of education and occupation with prevalent T2DM. The mediation models with incident T2DM and social support were not significant. Conclusion: Socioeconomic inequalities in T2DM were present, but only a small part of it was explained by the psychosocial work environment.

Association of the Amount and Pattern of Physical Activity With Arterial Stiffness: The Maastricht Study

We examined the associations of the amount and the pattern of higher intensity physical activity with arterial stiffness. Data from The Maastricht Study (n=1699; mean age: 60±8 years, 49.4% women, 26.9% type 2 diabetes (T2DM)) were used. Arterial stiffness was assessed by carotid-to-femoral pulse wave velocity (cfPWV). The amount (hours/day) and pattern of higher intensity physical activity were assessed with the activPAL3®. Activity groups were: inactive (<75min/week), insufficiently active (75-150min/week), weekend warrior (>150min/week in ≤2 sessions), and regularly active (>150min/week in ≥3 sessions). After full adjustment, higher intensity physical activity was associated with lower cfPWV (amount: -0.35[-0.65;-0.05], insufficiently active: -0.33[-0.55;-0.11]; weekend warrior: -0.38[-0.64;-0.12] and regularly active: -0.46[-0.71;-0.21] (reference: inactive)). These associations were stronger in those with T2DM. Participating in higher intensity physical activity was associated with lower cfPWV, regardless of the weekly pattern, and may be an important strategy to reduce CVD risk, particularly in T2DM.

Potential Markers of Dietary Glycemic Exposures for Sustained Dietary Interventions in Populations without Diabetes

There is considerable interest in dietary and other approaches to maintaining blood glucose concentrations within the normal range and minimizing exposure to postprandial hyperglycemic excursions. The accepted marker to evaluate the sustained maintenance of normal blood glucose concentrations is glycated hemoglobin A1c (HbA1c). However, although this is used in clinical practice to monitor glycemic control in patients with diabetes, it has a number of drawbacks as a marker of efficacy of dietary interventions that might beneficially affect glycemic control in people without diabetes. Other markers that reflect shorter-term glycemic exposures have been studied and proposed, but consensus on the use and relevance of these markers is lacking. We have carried out a systematic search for studies that have tested the responsiveness of 6 possible alternatives to HbA1c as markers of sustained variation in glycemic exposures and thus their potential applicability for use in dietary intervention trials in subjects without diabetes: 1,5-anhydroglucitol (1,5-AG), dicarbonyl stress, fructosamine, glycated albumin (GA), advanced glycated end products (AGEs), and metabolomic profiles. The results suggest that GA may be the most promising for this purpose, but values may be confounded by effects of fat mass. 1,5-AG and fructosamine are probably not sensitive enough to the range of variation in glycemic exposures observed in healthy individuals. Use of measures based on dicarbonyls, AGEs, or metabolomic profiles would require further research into possible specific molecular species of interest. At present, none of the markers considered here is sufficiently validated and sensitive for routine use in substantiating the effects of sustained variation in dietary glycemic exposures in people without diabetes.

Adulthood Socioeconomic Position and Type 2 Diabetes Mellitus-A Comparison of Education, Occupation, Income, and Material Deprivation: The Maastricht Study

In an effort to better quantify the impact of adulthood socioeconomic circumstances on prediabetes and type 2 diabetes (T2DM), we set out to examine the relative importance of four adulthood socioeconomic indicators. Using cross-sectional data from The Maastricht Study on 2011 middle-aged older men and women, our findings indicate that low educational level (OR = 1.81, 95% CI = 1.24-2.64), low occupational level (OR = 1.42, 95% CI = 0.98-2.05), and material deprivation (OR = 1.78, 95% CI = 1.33-2.38) were independently associated with T2DM. Low income (OR = 1.28, 95% CI = 0.88-1.87) was the strongest, albeit not significant, SEP (socioeconomic position) correlate of prediabetes. This association confirms SEP as a multifaceted concept and indicates the need to measure SEP accordingly. In order to tackle the social gradient in prediabetes and T2DM, one should, therefore, address multiple SEP indicators and their possible pathways.

Metformin and β-cell function in insulin-treated patients with type 2 diabetes: A randomized placebo-controlled 4.3-year trial

In this trial, 390 insulin-treated patients with type 2 diabetes were randomized to either placebo or metformin. Fasting levels of glucose, insulin and C peptide were determined at baseline, after 4 months and yearly thereafter for 4 years to assess fasting estimates of beta cell function. The primary endpoint was the fasting C peptide-to-glucose ratio (FCPGR) and secondary measures were the disposition index (DI) and the fasting C peptide (FCP). We analysed the results with a general linear mixed model. Baseline FCPGR was 5.27 (95% CI, 4.83 - 5.71). Compared to placebo, FCPGR increased in the metformin group with 1.48 (95% CI, 1.09 - 1.87, P < 0.001). The DI showed comparable results with a treatment effect of 1.50 (95% CI, 1.17 - 1.83; P < 0.001). FCP also increased in the metformin group but did not reach statistical significance vs placebo (0.034 nmol, 95% CI, -0.005 - 0.072; P = 0.085). Treatment with metformin vs placebo, added to insulin in patients with type 2 diabetes, improves long-term estimates of beta cell function in the fasting state.

Alcohol Consumption and Common Carotid Intima-Media Thickness: The USE-IMT Study

Aims

Epidemiological evidence indicates a protective effect of light to moderate alcohol consumption compared to non-drinking and heavy drinking. Although several mechanisms have been suggested, the effect of alcohol on atherosclerotic changes in vessel walls is unclear. Therefore, we explored the relationship between alcohol consumption and common carotid intima media thickness, a marker of early atherosclerosis in the general population.

Methods

Individual participant data from eight cohorts, involving 37,494 individuals from the USE-IMT collaboration were used. Multilevel age and sex adjusted linear regression models were applied to estimate mean differences in common carotid intima-media thickness (CIMT) with alcohol consumption.

Results

The mean age was 57.9 years (SD 8.6) and the mean CIMT was 0.75 mm (SD 0.177). About, 40.5% reported no alcohol consumed, and among those who drank, mean consumption was 13.3 g per day (SD 16.4). Those consuming no alcohol or a very small amount (<5 g per day) had significantly lower common CIMT values than those consuming >10 g per day, after adjusting for a range of confounding factors.

Conclusion

In this large CIMT consortium, we did not find evidence to support a protective effect of alcohol on CIMT.

Metformin-associated prevention of weight gain in insulin-treated type 2 diabetic patients cannot be explained by decreased energy intake: A post hoc analysis of a randomized placebo-controlled 4.3-year trial

Metformin prevents weight gain in patients with type 2 diabetes (T2D). However, the mechanisms involved are still unknown. In this post hoc analysis of the HOME trial, we aimed to determine whether metformin affects energy intake. Patients with T2D were treated with 850 mg metformin or received placebo added to insulin (1-3 times daily) for 4.3 years. Dietary intake was assessed at baseline, after 1 year and after 4.3 years, according to the dietary history method. Among the 310 included participants, 179 (93 placebo, 86 metformin) completed all 3 dietary assessments. We found no significant difference in energy intake after 4.3 years between the groups (metformin vs placebo: -31.0 kcal/d; 95% CI, -107.4 to 45.4; F-value, 1.3; df = 415; P = .27). Body weight in placebo users increased significantly more than in metformin-users during 4.3 years (4.9 ± 4.9 vs 1.1 ± 5.2 kg; t test: P ≤ .001). Linear mixed models did not show a significant effect of energy intake as explanation for the difference in weight gain between the groups (F-value, 0.1; df = 1; P = .82). In conclusion, the prevention of weight gain by metformin cannot be explained by reduced energy intake.

Increased C-reactive Protein Levels during Short-term Hormone Replacement Therapy in Healthy Postmenopausal Women

Objective: To study the short-term effect of unopposed oestradiol (E2) and sequentially combined hormone replacement therapy (E2 + P) on C-reactive protein (CRP) in healthy postmenopausal women. Design: Prospective, randomised, placebo-controlled 12-week study. Sixty healthy, normotensive, non-hysterectomised postmenopausal women received either placebo (N = 16) or daily 2 mg micronised oestradiol, either unopposed (N = 16, E2 group) or sequentially combined with a progestagen on 14 days of each cycle (N = 28, E2+P group). Data were collected at baseline and at 4 and 12 weeks. Results: CRP levels increased significantly during the 12 weeks in the E2 and the E2+P groups compared to placebo. No differences were found between the E2 group and the E2+P group [E2 and E2+P group together (N = 44) versus placebo: P = 0.01; E2 versus E2+P: P = 0.75]. To give a quantitative estimate of the increase, the median change calculated from baseline in both treatment groups together was +87% (P = 0.02) at 4 weeks, and +114% (P = 0.08) at 12 weeks, as compared to the placebo group. Conclusion: In healthy postmenopausal women, short-term treatment with E2 or E2+P was associated with a rapid rise in CRP concentrations. These observations raise the possibility that the increased risk of cardiovascular events is related to an initial increase in CRP levels after starting hormone replacement therapy.

von Willebrand Factor (vWf) as a Plasma Marker of Endothelial Activation in Diabetes: Improved Reliability with Parallel Determination of the vWf Propeptide (vWf:AgII)

Elevated plasma von Willebrand factor (vWf) levels are found in diabetes and other vasculopathies, and predict cardiovascular mortality. vWf is stored and released from endothelial cell secretory granules, along with equimolar amounts of its propeptide (vWf:AgII). In the present study, we examined plasma propeptide levels as a marker of endothelial secretion in vivo, using an ELISA based on monoclonal antibodies. vWf but not propeptide levels are influenced by blood groups, explaining in part the smaller variation in plasma propeptide levels among normal individuals. In both controls and insulin-dependent diabetic patients, we found a close correlation between propeptide and immunoreactive vWf levels (r2 = 0.54, p <0.0001). vWf and propeptide were elevated in patient subgroups with microalbuminuria or overt diabetic nephropathy, whereas only the propeptide was significantly elevated in the normoalbuminuric subgroup. This observation suggests that in conjunction with vWf, propeptide measurements may improve the identification of endothelial activation, which occurs frequently even without increased urinary albumin excretion. In 12 NIDDM patients, a 3-week diet enriched in monounsaturated fat (MUFA) resulted in parallel decreases in vWf (-22%, p <0.05) and propeptide (-17%, p <0.05) levels, indicating that the experimental diet affected endothelial secretion rather than vWf catabolism. A carbohydrate-enriched control diet did not significantly influence either marker.

Our results suggest that concomittant determinations of plasma vWf and propeptide are useful tools to assess endothelial activation in vivo, and reinforce our previous conclusion that a diet rich in MUFA can improve endothelial function in NIDDM.

Impaired Procoagulant-anticoagulant Balance during Hormone Replacement Therapy?

In this randomised, placebo-controlled 12-week study, sixty healthy postmenopausal women received either placebo (N = 16) or daily 2 mg micronised oestradiol, either unopposed (N = 16, E2 group) or combined with a progestagen for 14 days of each cycle (N = 28, E2+P group).

As compared to placebo, plasma levels of AT III were reduced only in the E2 group (∼28%), plasma levels of protein C decreased only in the E2+P group (∼4%) and plasma levels of protein S decreased in both the E2 and E2+P group (∼21%). In both the E2 and E2+P groups, the plasma levels of factor VII (antigen and activity) showed a borderline significant increase (∼10%), whereas no significant change was observed in active factor VII. Plasma levels of tissue-type plasminogen activator (∼22%), urokinase plasminogen activator (∼25%) and plasminogen activator inhibitor type-1 (∼43%) decreased in the E2 and E2+P groups, whereas those of plasminogen increased (∼12%). Treatment was associated with an increase in levels of prothrombin fragment 1+2 (∼31%), but levels of thrombin-antithrombin III complexes, and of plasmin-α2-antiplasmin complexes and total fibrin(ogen) degradation products did not change significantly.

Short-term E2 and E2+P treatment is associated with a shift in the procoagulant-anticoagulant balance towards a procoagulant state. A substantial proportion of women do not have a net increase in fibrinolytic activity. These data may be relevant in explaining the increased risk of venous thromboembolism associated with ERT and HRT, and possibly also in explaining the negative results of the Heart and Estrogen/progestin Replacement Study.

Glyoxalase-1 overexpression partially prevents diabetes-induced impaired arteriogenesis in a rat hindlimb ligation model

We hypothesize that diabetes-induced impaired collateral formation after a hindlimb ligation in rats is in part caused by intracellular glycation and that overexpression of glyoxalase-I (GLO-I), i.e. the major detoxifying enzyme for advanced-glycation-endproduct (AGE) precursors, can prevent this. Wild-type and GLO-I transgenic rats with or without diabetes (induced by 55 mg/kg streptozotocin) were subjected to ligation of the right femoral artery. Laser Doppler perfusion imaging showed a significantly decreased blood perfusion recovery after 6 days in the diabetic animals compared with control animals, without any effect of Glo1 overexpression. In vivo time-of-flight magnetic resonance angiography at 7-Tesla showed a significant decrease in the number and volume of collaterals in the wild-type diabetic animals compared with the control animals. Glo1 overexpression partially prevented this decrease in the diabetic animals. Diabetes-induced impairment of arteriogenic adaptation can be partially rescued by overexpressing of GLO-I, indicating a role of AGEs in diabetes-induced impaired collateral formation.

Markers of inflammation and endothelial dysfunction are associated with incident cardiovascular disease, all-cause mortality, and progression of coronary calcification in type 2 diabetic patients with microalbuminuria

BACKGROUND

We evaluated markers of inflammation and endothelial dysfunction and their associations with incident cardiovascular disease (CVD), all-cause mortality and progression of coronary artery calcium (CAC) in patients with type 2 diabetes (T2D) and microalbuminuria but without known coronary artery disease (CAD).

METHODS

Prospective study including 200 patients receiving multifactorial treatment. Markers of inflammation (TNF-ɑ, sICAM-1, sICAM-3, hsCRP, SAA, IL-1β, IL-6, IL-8) and endothelial dysfunction (thrombomodulin, sVCAM-1, sICAM-1, sICAM-3, sE-selectin, sP-selectin) were measured at baseline. Adjustment included traditional CVD risk factors, and full adjustment additionally NT-proBNP and CAC. The "SQRT method" assessed CAC progression after 5.8years, and cut-point was an annualised difference >2.5.

RESULTS

Occurrence of CVD (n=40) and all-cause mortality (n=26) was traced after 6.1years. In adjusted and fully adjusted Cox models, TNF-ɑ was a determinant of CVD and all-cause mortality (p≤0.007). Further, in adjusted and fully adjusted logistic regression, TNF-ɑ was related to CAC progression (p≤0.042). Of the other biomarkers, sICAM-3 and thrombomodulin were also associated with both endpoints (p≤0.046), IL-1β with CVD endpoints (p=0.021), and sVCAM-1 and sICAM-1 with all-cause mortality (p≤0.005). Higher composite z-scores including all markers of inflammation and endothelial dysfunction were associated with CVD and all-cause mortality (p≤0.008).

CONCLUSIONS

In patients with T2D and microalbuminuria without known CAD and receiving multifactorial treatment, biomarkers of inflammation and endothelial dysfunction were independently associated with CVD, all-cause mortality and CAC progression. Especially TNF-ɑ was a robust determinant, even after adjusting for NT-proBNP and CAC.

The association between the metabolic syndrome and alanine amino transferase is mediated by insulin resistance via related metabolic intermediates (the Cohort on Diabetes and Atherosclerosis Maastricht [CODAM] study)

The metabolic syndrome is associated with nonalcoholic fatty liver disease (NAFLD) as well as with insulin resistance, inflammatory adipokines, endothelial dysfunction, and higher plasma levels of nonesterified fatty acids (NEFA), all of which may also affect the development of NAFLD. Therefore, we investigated to what extent the association between the metabolic syndrome and alanine aminotransferase (ALT, as a surrogate of NAFLD) can be explained by different metabolic intermediates of the metabolic syndrome. Cross-sectional analyses were performed in 434 subjects from the Cohort on Diabetes and Atherosclerosis Maastricht study (264 men; mean age, 59.5 ± 7.1 years). We used multiple linear regression analyses to investigate the association between the metabolic syndrome and ALT and the mediation role of potential mediators herein. The mediators considered were insulin resistance (homeostasis model assessment), an inflammatory adipokine score (based on interleukin-6, serum amyloid A, intercellular adhesion molecule, adiponectin, and leptin), an endothelial dysfunction score (based on E-selectin, vascular cell adhesion molecule, and von Willebrand factor), and plasma levels of NEFA. All analyses were adjusted for age, sex, smoking, alcohol consumption, and use of medication. Subjects with the metabolic syndrome (53.7%) had significantly higher levels of ALT (β = 0.67 SD [95% confidence interval, 0.49-0.85], P < .001). Adjustment for insulin resistance attenuated this difference by 77.3% (to 0.15 SD [-0.04 to 0.35]). Attenuation by adipose tissue-associated inflammation, endothelial dysfunction, and NEFA was more modest (20.7%, 13.1%, and 9.5%, respectively). Part of the attenuation by NEFA, but not of the other mediators, was additional to that of insulin resistance. Insulin resistance constitutes a key pathophysiological mechanism in the association between the metabolic syndrome and NAFLD (measured as ALT), which may operate through adipose tissue-associated inflammation and endothelial dysfunction and to a lesser extent through NEFA, which may have an independent role in the development of NAFLD in subjects with the metabolic syndrome.

N epsilon-(carboxymethyl)lysine during the early development of hypertension

Advanced glycation end products (AGEs) are associated with hypertension. Whether N(epsilon)-(carboxymethyl)lysine (CML) contributes to the development of hypertension in young spontaneously hypertensive rats (SHR) remains to be established compared to WKY. We determined blood pressure, renal function, marker for oxidative stress (OS), and CML in young WKY rats and SHR. We found blood pressure was increased in SHR with no difference in renal function and OS compared to WKY. CML was elevated in plasma (2.3 +/- 0.3 vs. 1.3 +/- 0.2 micromol/L) and kidney (1.0 +/- 0.1 vs. 0.5 +/- 0.1 micromol/L) compared to WKY. Early CML accumulation may contribute to the development of hypertension potentially by inducing early renal inflammation independent of glomerular dysfunction or oxidative stress.

Depression and the risk for cardiovascular diseases: systematic review and meta analysis

BACKGROUND

Depression and cardiovascular diseases are both common among elderly. Depression is suspected to be an independent risk factor for the onset of coronary heart disease, yet it is not clear to what extent and if depression also is associated with the onset of other diseases of the circulatory system.

AIMS

To estimate the risk of depression as an independent risk factor for various cardiovascular diseases (CVD) and explore the effects of heterogeneity and methodological quality.

METHOD

Meta-analyses and meta-regression analyses of longitudinal cohort and case-control studies reporting depression at baseline and CVD outcomes at follow-up.

DATA SOURCES

MEDLINE (1966-2005) and PSYCHINFO (1966-2005).

RESULTS

Of the 28 studies that met the inclusion criteria, 11 were assesed as high quality studies. Although depressed mood increased the risk for a wide range of CVDs, heterogeneity was substantial in most cases. Only the overall combined risk of depression for the onset of myocardial infarctions (n=8, OR=1.60, 95%CI 1.34-1.92) was homogenous. Clinically diagnosed major depressive disorder was identified as the most important risk factor for developing CVD.

CONCLUSIONS

Depression seems to be an independent risk factor for the onset of a wide range of CVDs, although this evidence is related to a high level of heterogeneity.

Insulin sensitivity correlates with glycogen synthesis rate, but not with von Willebrand factor in type 2 diabetes

BACKGROUND: Whether insulin resistance in type 2 (non-insulin-dependent) diabetes is due to compromised endothelial insulin migration or to impaired intracellular hormone action or both is unclear. Coexistent microalbuminuria reflects possible endothelial pathogenesis in insulin resistance. METHODS: Insulin sensitivity (S(I)) was calculated from an intravenous glucose tolerance test in 23 type 2 albuminuric (AER+), 11 type 2 normoalbuminuric (AER-), and 17 control subjects. Cultured fibroblasts from skin biopsies from these subjects were used to study intracellular insulin action on glycogen synthesis. Endothelial damage in type 2 diabetes was evaluated by plasma concentrations of von Willebrand factor (vWf). Results: S(I) and glycogen synthesis in fibroblasts were lower in AER+ and AER- than in controls. Glycogen synthesis in vitro was related to S(I) in vivo (r=0.55, P<0.001). vWf was 169+/-12% in AER+ and 140+/-5% in AER-, P<0.051. No correlation was observed between vWf and S(I) or plasma insulin clearance. CONCLUSIONS: This study demonstrates that reduced insulin-mediated glucose removal in type 2 diabetes is strictly associated with a decreased glycogen synthesis of cultured skin fibroblasts in vitro, but not with markers of endothelial damage in vivo.

Total plasma homocysteine is associated with hypertension in Type I diabetic patients

AIMS/HYPOTHESIS

Although hyperhomocysteinaemia and methylenetetrahydrofolate reductase gene polymorphism are accepted risk factors for cardiovascular disease, their association with micro angiopathy or blood pressure in diabetic patients is still being debated. This study explores the relation between plasma homocysteine concentrations, methylenetetrahydrofolate reductase gene polymorphism, hypertension, diabetic microvascular and macrovascular complications associated with kidney function.

METHODS

Vascular complications, hypertension, methylenetetrahydrofolate reductase genotype (RFLP with Hinf I digestion), and total plasma homocysteine (HPLC) were investigated in 389 well-characterized Type I (insulin-dependent) diabetic patients with normal (GFR> or=75 ml x min(-1) x (1.73 m(2))(-1); n=273), or impaired renal function (GFR <75 ml x min(-1) x (1.73 m(2))(-1); n=116).

RESULTS

Patients with microvascular and macrovascular complications showed higher total plasma homocysteine concentrations than those without complications. However, after the data for GFR (main determinant for plasma homocysteine) was adjusted we observed that plasma homocysteine concentrations greater than 8.6 micro mol/l in patients with normal GFR are not related to vascular complications, but to hypertension (8.6-11.3 micro mol/l: OR 1.9; >11.3 micro mol/l: OR 3.7). The risk for coronary heart disease (CHD) was also enhanced by a plasma homocysteine concentration greater than 11.3 micro mol/l (OR 5.9). Although the T allele was an independent determinant of plasma homocysteine, the methylenetetrahydrofolate reductase gene polymorphism was neither associated with diabetic vascular complications nor with hypertension.

CONCLUSION/INTERPRETATION

Increased plasma homocysteine concentrations but not the T allele per se, enhance the risk of hypertension and of CHD in Danish Type I diabetic patients with normal renal function.

The influence of improved glycaemic control with insulin and sulphonylureas on acute phase and endothelial markers in Type II diabetic subjects

AIMS/HYPOTHESIS

Improved glycaemic control might reduce both microvascular and macrovascular complications of Type II diabetes (non-insulin-dependent) mellitus. To explore such possible mechanisms, we investigated the effects of intensive treatment on markers of endothelial dysfunction and of acute phase activation, using both sulphonylureas and insulin.

METHODS

In a randomised cross-over study we gave sulphonylureas or insulin each for a period of 16 weeks to 22 poorly controlled Type II diabetic subjects who were being treated by diet. There was a 4 week washout period between each treatment. Subjects were studied at baseline and at the end of each treatment.

RESULTS

Treatment with sulphonylureas and insulin resulted in similar improvements in glycaemic control (glycated haemoglobin, baseline: 11.8 [(SD 2.2)%; after sulphonylureas: 8.6 (1.2)%,p < 0.001; after insulin: 8.6 (1.2)%, p < 0.001] and in insulin sensitivity ¿metabolic clearance rate of glucose, baseline: median 1.75 [interquartile (IQ) range 1.41, 2.27] ml x kg(-1) x min(-1); after sulphonylureas: 2.41 (1.82, 3.01) ml x kg(-1) x min(-1), p = 0.001; after insulin: 2.23 (1.92, 2.75) ml x kg(-1) min(-1), p = 0.027¿. There were no significant changes in concentrations of endothelial markers von Willebrand factor, cellular fibronectin, thrombomodulin, tissue plasminogen activator, soluble E-selectin or soluble intercellular adhesion molecule-1 or in urinary albumin excretion rate after either treatment period. Concentrations of C-reactive protein were not significantly influenced by sulphonylureas but fell after insulin [baseline: median 4.50 (IQ range 1.37, 6.44) microg x ml(-1); sulphonylureas: 2.69 (0.88, 9.65) microg x ml(-1) (p = 0.53); insulin: 2.07 (1.16, 5.24) microg x ml(-1) (p = 0.017)]. There were, however, no significant effects of either treatment on circulating concentrations of fibrinogen (p = 0.28-0.34) or of the proinflammatory cytokines interleukin-6 or tumour necrosis factor-alpha (p = 0.65-0.79).

CONCLUSION/INTERPRETATION

Markers of endothelial dysfunction and concentrations of proinflammatory cytokines in Type II diabetes are not influenced by improved glycaemic control over 16 weeks. Improved metabolic control with insulin could, however, be associated with reduced concentrations of the acute phase marker C-reactive protein.

Distinct Associations of HbA1c and the Urinary Excretion of Pentosidine, an Advanced Glycosylation End-product, with Markers of Endothelial Function in Insulin-dependent Diabetes mellitus

Dysfunction of the vascular endothelium is considered an early step in the development of diabetic angiopathy. Hyperglycaemia results in endothelial dysfunction, both through direct effects of glucose and through formation of advanced glycosylation end-products (AGEs). We hypothesized that the effects of glucose and AGEs on endothelial function in insulin-dependent diabetes mellitus (IDDM) are distinct and are reflected by distinct plasma markers of endothelial function. We therefore measured plasma levels of von Willebrand factor (vWF), soluble (s) E-selectin and vascular cell adhesion molecule-1 (sVCAM-1), and evaluated the relationship with HbA1c and urinary excretion of pentosidine, an AGE product, in 56 patients with IDDM. Urinary pentosidine excretion was higher in the diabetic than in a control group (n = 60) of similar age (P <0.0001) and showed a steeper increase with age (P <0.02 vs controls). In the diabetic group, sE-selectin was correlated to HbA1c (r = 0.52, P <0.0001), whereas sVCAM-1 was not (r = 0.11, P = 0.47). In contrast, sVCAM-1 showed a trend towards a correlation with log (pentosidine excretion) (r = 0.27, P = 0.06), whereas sE-selectin did not (r = –0.16, P = 0.27). Log(vWF) was correlated to HbA1c (r = 0.50, P <0.0001) and tended to correlate with log (pentosidine excretion) (r = 0.25, P = 0.07). Multivariate analyses with both pentosidine and HbA1c as independent variables showed significant associations of sE-selectin with HbA1c, of sVCAM-1 with pentosidine, and of log(vWF) with both HbA1c and pentosidine (all P-values <0.02). Our results imply that the effects of glucose and AGEs on the endothelium can be reflected by distinct endothelial markers. Plasma sE-selectin may reflect short-term effects of glucose on the endothelium, sVCAM-1 the effects of AGEs, and vWF the combined effect of glucose and AGEs.