Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Efficacy and short-term safety of a new ACAT inhibitor, avasimibe, on lipids, lipoproteins, and apolipoproteins, in patients with combined hyperlipidemia

Although acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors have been shown to reduce lipid levels in several animal models, the safety and lipid modifying activity of any single agent in this class has not been demonstrated in humans. The safety and efficacy of avasimibe (CI-1011), a new, unique, wholly synthetic ACAT inhibitor, was evaluated in the treatment of 130 men and women with combined hyperlipidemia and hypoalphalipoproteinemia (low levels of high-density lipoprotein cholesterol [HDL-C]). Following an 8-week placebo and dietary-controlled baseline period, patients were randomly assigned to double-blind treatment with placebo, 50, 125, 250, or 500 mg avasimibe administered as capsules once daily for 8 weeks. At all evaluated doses, avasimibe treatment resulted in prompt and significant reductions (P<0.05) in plasma levels of total triglycerides (TG) and very low-density lipoprotein cholesterol (VLDL-C) with mean reductions of up to 23% and 30% respectively, apparently independent of dose. No statistically significant changes in total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), HDL-C or apolipoprotein (apo) B were detected. ApoAI levels were also unchanged on all doses of avasimibe apart from the 500 mg dosage, which was associated with a significant decrease in plasma apoAI. The relevance of this latter finding in only one dosage group is not known. All doses of avasimibe were well tolerated with no resulting significant abnormalities of biochemical, hematological, or clinical parameters.

Efficacy and safety of combination simvastatin and colesevelam in patients with primary hypercholesterolemia

PURPOSE

To examine the efficacy and safety of colesevelam hydrochloride, a novel, nonsystemic, lipid-lowering agent, when coadministered with starting doses of simvastatin in a multicenter, randomized, double-blind, placebo-controlled trial.

PATIENTS AND METHODS

Subjects with hypercholesterolemia (plasma low density lipoprotein [LDL] cholesterol level > 160 mg/dL and triglyceride level < or = 300 mg/dL) were randomly assigned to receive daily doses of placebo (n = 33), colesevelam 3.8 g (recommended dose, n = 37), simvastatin 10 mg (n = 35), colesevelam 3.8 g with simvastatin 10 mg (n = 34), colesevelam 2.3 g (low dose, n = 36), simvastatin 20 mg (n = 39), or colesevelam 2.3 g with simvastatin 20 mg (n = 37), for 6 weeks.

RESULTS

Mean LDL cholesterol levels decreased relative to baseline in the placebo group (P < 0.05) and in all active treatment groups (P < 0.0001). For groups treated with combination therapy, the mean reduction in LDL cholesterol level was 42% (-80 mg/dL; P < 0.0001 compared with baseline), which exceeded the reductions for simvastatin 10 mg (-26%, -48 mg/dL) or 20 mg (-34%, -61 mg/dL) alone, or for colesevelam 2.3 g (-8%, -17 mg/dL) or 3.8 g (-16%, -31 mg/dL) alone (P < 0.001). The effects of combination therapy on serum HDL cholesterol and triglyceride levels were similar to those for simvastatin alone. Side effects were similar among treatment groups, and there were no clinically important changes in laboratory parameters.

CONCLUSION

Coadministration of colesevelam and simvastatin was effective and well tolerated, providing additive reductions in LDL cholesterol levels compared with either agent alone.

Effects of high-dose simvastatin on adrenal and gonadal steroidogenesis in men with hypercholesterolemia

In view of the role of both the de novo biosynthesis and receptor-mediated uptake of cholesterol for normal steroidogenesis, we evaluated whether extending the therapeutic dose of the hepatic hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibitor, simvastatin, to 80 mg/d would affect adrenal and gonadal steroid synthesis in men with hypercholesterolemia. To evaluate this question, we enrolled men into a multicenter randomized, placebo-controlled study lasting 12 weeks. Men with serum low-density lipoprotein cholesterol (LDL-C) more than 145 mg/dL after 6 weeks of a lipid-lowering diet were randomized to 80 mg simvastatin or placebo. Half of the subjects were asked to undergo a 6-hour infusion of corticotropin (ACTH) to evaluate cortisol synthesis, and the entire cohort received a human chorionic gonadotropin (hCG) stimulation test to assess gonadal hormone secretion using pooled serum samples taken 15 minutes apart. A total of 81 men (age, 45 +/- 11 years; 93% Caucasian) with baseline serum LDL-C of 197 mg/dL (placebo, n = 39) and 184 mg/dL (simvastatin 80 mg, n = 42) completed the study. After 12 weeks, serum LDL-C, triglycerides, and high-density lipoprotein cholesterol (HDL-C) in the simvastatin group changed by -43%, -25%, and 8%, respectively (all P < .001). The basal cortisol level and the peak serum cortisol and area under the curve response to the 6-hour ACTH infusion were comparable between the two treatment groups at baseline and after 12 weeks. The pooled total testosterone level at baseline was 541 and 513 ng/dL in the placebo and simvastatin-treated groups, respectively, which declined to 536 +/- 20.5 ng/dL (-1.5%) and 474 +/- 30.4 ng/dL (-13.6%, P = .09) after treatment (mean +/- SD). The pooled free testosterone declined by 6.3% in the simvastatin group, versus a 4.9% increase in the placebo group (P = .588), while pooled bioavailable testosterone declined 10.2% in the simvastatin group and increased 1.4% in the placebo group (P = .035). There were no changes in serum gonadotropin levels or sex hormone-binding globulin (SHBG). After administration of hCG, there were no differences in the peak total pooled testosterone level before or after 12 weeks of treatment. Simvastatin 80 mg was well tolerated compared with placebo. In conclusion, basal and stimulated cortisol production was unaffected by the use of simvastatin 80 mg versus placebo. As reported with other statins and cholestyramine, there were small declines in the simvastatin-treated group for pooled total, free, and bioavailable testosterone after 12 weeks, although there was no compensatory increase in serum follicle-stimulating hormone (FSH) or luteinizing hormone (LH) levels.

Treating to meet NCEP-recommended LDL cholesterol concentrations with atorvastatin, fluvastatin, lovastatin, or simvastatin in patients with risk factors for coronary heart disease

BACKGROUND

Our study compared use of atorvastatin, fluvastatin, lovastatin, and simvastatin for lowering low-density lipoprotein (LDL) cholesterol concentration in patients at risk for coronary heart disease (CHD). The goal was to reach the LDL cholesterol levels recommended by the National Cholesterol Education Program (NCEP).

METHODS

A combined total of 344 men and women took part in this 54-week, multicenter, open-label, randomized, parallel-group, active-controlled, treat-to-target study. Patients were selected on the basis of their LDL cholesterol concentration and their risk for CHD. During treatment, doses were titrated at 12-week intervals to a maximum of 80 mg per day of atorvastatin and lovastatin, or 40 mg per day of fluvastatin and simvastatin, with colestipol added if necessary to attain the NCEP-recommended LDL cholesterol concentration.

RESULTS

At the starting dose, atorvastatin decreased plasma LDL cholesterol significantly (P < .05) compared with the other reductase inhibitors, and the percentage of patients reaching target LDL cholesterol concentration at the starting dose was significantly greater in the atorvastatin group (P < .05). Overall, a significantly (P < .05) greater percentage (95%) of atorvastatin-treated patients achieved target LDL cholesterol concentration. The safety profile was similar among all reductase inhibitors tested.

CONCLUSIONS

At the starting dose, a significantly (P < .05) greater percentage of atorvastatin-treated patients at risk for CHD reached the target LDL cholesterol concentration than patients with treated with other reductase inhibitors.

Effect of postmenopausal hormone therapy on glucose and insulin concentrations. PEPI Investigators. Postmenopausal Estrogen/Progestin Interventions

OBJECTIVE

To characterize the long-term impact of four hormone therapy regimens on insulin and glucose concentrations measured during a standard oral glucose tolerance test.

RESEARCH DESIGN AND METHODS

The Postmenopausal Estrogen/Progestin Intervention Study was a 3-year placebo-controlled randomized trial to assess effects of four hormone regimens on cardiovascular risk factors. This efficacy analysis describes glucose and insulin concentrations from 788 adherent women at baseline and at 1 and 3 years' postrandomization.

RESULTS

When compared with women taking placebo, those taking conjugated equine estrogen (CEE) at 0.625 mg/day with or without a progestational agent had mean fasting insulin levels that were 16.1% lower, mean fasting glucose levels 2.2 mg/dl lower, and mean 2-h glucose levels 6.4 mg/dl higher (each nominal P < 0.05). No significant differences were apparent between women taking CEE only versus the three progestin regimens: medroxyprogesterone acetate (MPA) at 2.5 mg daily (continuous MPA), MPA at 10 mg on days 1-12 (cyclical MPA), and micronized progesterone (MP) (cyclical) at 200 mg on days 1-12. The impact of hormone therapy on insulin and glucose depended on baseline levels of fasting insulin and 1-h glucose (P < 0.05). However, the treatment effects on carbohydrate metabolism appeared to be consistent across participant subgroups formed by lifestyle, clinical, and demographic characteristics.

CONCLUSIONS

Oral hormone therapy involving 0.625 mg/day of CEE may modestly decrease fasting levels of insulin and glucose. Postchallenge glucose concentrations are increased, however, which may indicate delayed glucose clearance.

Efficacy and safety of simvastatin 80 mg/day in hypercholesterolemic patients. The Expanded Dose Simvastatin U.S. Study Group

This randomized, multicenter, double-blind parallel-group study was performed to evaluate the lipid-altering efficacy and safety of simvastatin 80 mg/day, a dose twice the current maximum recommended dose. At 20 centers in the United States, 521 male and female hypercholesterolemic patients were randomly assigned in a ratio of 2:3 to receive simvastatin 40 or 80 mg once daily, respectively, for 24 weeks in conjunction with a lipid-lowering diet. Patients met National Cholesterol Education Program (NCEP) low-density lipoprotein (LDL) cholesterol criteria for pharmacologic treatment. The mean percentage reductions (95% confidence intervals) from baseline in LDL cholesterol averaged at weeks 18 and 24 were 38% (-40 to -36) and 46% (-47 to -45) for the 40- and 80-mg groups, respectively (p <0.001 between groups). One third of patients on the 40- and 80-mg doses achieved an LDL cholesterol reduction of 46% and > or = 53%, respectively. Decreases in apolipoprotein B, total cholesterol, and triglycerides were also significantly greater among patients receiving 80 mg/day. Simvastatin was well tolerated in both groups. Two patients (0.6%) in the 80-mg group developed myopathy. Consecutive, clinically significant hepatic transaminase elevations occurred in 3 (1.0%) and 6 (1.9%) patients in the 40- and 80-mg groups, respectively (p= 0.486). In conclusion, simvastatin 80 mg/day provided substantial reductions in LDL cholesterol, allowing most patients to reach their NCEP target levels; it also had an excellent safety and tolerability profile.

A Multicenter, Placebo-Controlled, Dose-Ranging Study of Atorvastatin

BACKGROUND: Coronary heart disease (CHD) is the number one cause of death in Western societies. Elevated levels of plasma low-density lipoprotein (LDL) cholesterol and triglycerides (TG) increase the risk for CHD. 3-Hydroxy-3-methylglutaryl conenzyme A (HMG-CoA) reductase inhibitors effectively reduce plasma cholesterol levels in patients with hypercholesterolemia. This study assesses the safety and dose-related effects of atorvastatin calcium on lipoprotein fractions in patients with LDL cholesterol levels between 160 mg/dL (4.1 mM) and 250 mg/dL (6.5 mM) or less and TG levels of 400 mg/dL (4.5 mM) or less. METHODS AND RESULTS: Sixty-five patients were enrolled in a 6-week, randomized, placebo-controlled, parallel-group study. Patients received placebo or atorvastatin 10, 20, 40, 60, or 80 mg once daily. Adjusted mean decreases in LDL cholesterol for patients receiving atorvastatin 10, 20, 40, 60, and 80 mg were 37%, 42%, 50%, 52%, and 59%, respectively, compared with a mean increase of 0.3% for patients receiving placebo; the differences between each of the atorvastatin dose groups and placebo were statistically significant (P =.0001). Total cholesterol, triglycerides, and apolipoprotein B were significantly reduced in atorvastatin groups (P =.0001). Adverse events were similar in the placebo and atorvastatin treatment groups. No patient had a serious adverse event or withdrew because of an adverse event during this study. CONCLUSIONS: Atorvastatin effectively lowered plasma LDL cholesterol, triglycerides, and apoB levels in a dose-related manner. Atorvastatin was well tolerated in hyperlipidemic patients over a 6-week period.

Effect of postmenopausal hormone therapy on lipoprotein(a) concentration. PEPI Investigators. Postmenopausal Estrogen/Progestin Interventions

BACKGROUND

Postmenopausal hormone therapy has been reported to decrease levels of lipoprotein (Lp)(a) in cross-sectional studies and small or short-term longitudinal studies. We report findings from a large, prospective, placebo-controlled clinical trial that allows a broad characterization of these effects for four regimens of hormone therapy.

METHODS AND RESULT

The Postmenopausal Estrogen/Progestin Interventions study was a 3-year, placebo-controlled, randomized clinical trial to assess the effect of hormone regimens on cardiovascular disease risk factors in postmenopausal women 45 to 65 years of age. The active regimens were conjugated equine estrogens therapy at 0.625 mg daily, alone or in combination with each of three regimens of progestational agents: medroxyprogesterone acetate (MPA) at 2.5 mg daily (ie, continuous MPA), MPA at 10 mg days 1 to 12 (ie, cyclical MPA), and micronized progesterone at 200 mg days 1 to 12. Plasma levels of Lp(a) were measured at baseline (n = 366), 12 months (n = 354), and 36 months (n = 342). Assignment to hormone therapy resulted in a 17% to 23% average drop in Lp(a) concentrations relative to placebo (P<.0001), which was maintained across 3 years of follow-up. No significant differences were observed among the four active arms. Changes in Lp(a) associated with hormone therapy were positively correlated with changes in LDL cholesterol, total cholesterol, apolipoprotein B, and fibrinogen levels and were similar across subgroups defined by age, weight, ethnicity, and prior hormone use.

CONCLUSIONS

Postmenopausal estrogen therapy, with or without concomitant progestin regimens, produces consistent and sustained reductions in plasma Lp(a) concentrations.

Comparison of one-year efficacy and safety of atorvastatin versus lovastatin in primary hypercholesterolemia. Atorvastatin Study Group I

This double-blind study to evaluate long-term efficacy and safety of atorvastatin was performed in 31 community- and university-based research centers in the USA to directly compare a new 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor (reductase inhibitor) to an accepted drug of this class in patients with moderate hypercholesterolemia. Participants remained on a cholesterol-lowering diet throughout the study. One thousand forty-nine patients were randomized to receive atorvastatin 10 mg, lovastatin 20 mg, or placebo. At 16 weeks the placebo group was randomized to either atorvastatin or lovastatin treatment. At 22 weeks, patients who had not met low-density lipoprotein (LDL) cholesterol target levels doubled the dose of reductase inhibitor. Efficacy evaluation was mean percent change from baseline in LDL cholesterol, triglycerides, total cholesterol, high-density-lipoprotein cholesterol, and apolipoprotein B (apoB). Safety profiles as determined by change from baseline in laboratory evaluations, ophthalmologic parameters, and reporting of adverse events were similar for the 2 reductase inhibitors. After 52 weeks, the atorvastatin group maintained a significantly greater reduction in LDL cholesterol (-37% vs -29%), triglyceride (-16% vs -8%), total cholesterol (-27% vs -21%), and apoB (-30% vs -22%) (p <0.05). More patients receiving atorvastatin achieved LDL cholesterol target levels than did lovastatin patients (78% vs 63%, respectively), particularly those with coronary heart disease (37% vs 11%, respectively). Atorvastatin is highly effective and well tolerated in patients with primary hypercholesterolemia with no increased risk of adverse events.

Atorvastatin, a New HMG-CoA Reductase Inhibitor as Monotherapy and Combined With Colestipol

BACKGROUND: Atorvastatin, a new HMG-CoA reductase inhibitor in clinical development has demonstrated an acceptable safety profile and marked cholesterol and triglyceride reduction at doses ranging from 10-80 mg/day. Since bile acid sequestering resins are often used in combination with HMGRIs to enhance cholesterol reduction, this trial was conducted to explore the use of atorvastatin alone and combined with colestipol in patients with primary hyperlipidemia. METHODS AND RESULTS: One hundred six patients with low-density lipoprotein (LDL) cholesterol >4.1 mM/L (160 mg/dL) and plasma triglycerides <3.9 mM/L (350 mg/dL) were randomized to treatment consisting of 20 g/day colestipol, 10 mg/day atorvastatin, or 10 mg/day atorvastatin plus 20 g/day colestipol for 12 weeks. Percent change from baseline in lipid variables were measured. The atorvastatin group showed a significant reduction in LDL cholesterol of 35% after 12 weeks. Combination therapy provided an additional 10% reduction in LDL cholesterol over that observed for atorvastatin alone. Twenty-one percent of all patients in the atorvastatin monotherapy group experienced associated adverse events compared with 60% in the combination therapy group. Ninety percent of atorvastatin monotherapy patients were compliant at every visit compared with 75% receiving combination therapy. CONCLUSIONS: Although the combination of atorvastatin plus colestipol was more effective in lowering LDL cholesterol than atorvastatin alone, atorvastatin 10 mg/day monotherapy provided a better safety profile and improved patient compliance, which may result in improved long-term cholesterol control.

Once-daily, extended-release gemfibrozil in patients with dyslipidemia. The Lopid SR Work Group I

This randomized, parallel-group, multicenter clinical trial compared a newly developed, once-daily, extended-release formulation of gemfibrozil (Lopid SR) and gemfibrozil twice daily (Lopid) in terms of lipid-regulating effects and toxicity. Patients were men and women with elevations of low-density lipoprotein cholesterol and low levels of high-density lipoprotein cholesterol. The trial consisted of a 1-week screening period, an 8-week diet baseline period (Step One Diet), and a 24-week double-blind treatment period (extended-release gemfibrozil 1,200 mg once daily vs gemfibrozil 600 mg twice daily). At the end of the trial, the 2 treatment groups showed comparable improvements in all primary lipid factors: mean percent changes in triglyceride, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were -32, +10 and -10% for extended release (n = 325) and -36, +11 and -10% for twice daily (n = 330). The 90% confidence interval for the relative difference between the treatment means fell within the equivalence bounds of +/- 35% for all 3 factors, demonstrating equivalence of efficacy. Adverse events were reported at low rates and were similarly distributed in frequency and intensity between treatment groups; they were preponderantly mild or moderate, and gastrointestinal effects were the most frequent. The once-daily formulation of gemfibrozil may afford better control of dyslipidemia through improved compliance by patients who have this asymptomatic disease.

Strenuous physical activity, treadmill exercise test performance and plasma high-density lipoprotein cholesterol. The Lipid Research Clinics Program Prevalence Study

During the Lipid Research Clinics North American Prevalence Study, plasma lipoprotien determinations and treadmill exercise testing were performed on 2319 white men and 2067 white women ages 20 years or older randomly selected from population surveys by nine clinics in the U.S. and Canada. Before exercise testing, participants were asked if they performed any strenuous physical activity on a regular basis. Data were analyzed to determine the relationship of plasma high-density lipoprotein (HDL) cholesterol to treadmill exercise test performance and a self-report of strenuous activity. Neither treadmill exercise test duration nor heart rate response to submaximal exercise was significantly related to HDL cholesterol levels for either men or women. However, participants who reported some strenuous physical activity generally had higher HDL cholesterol levels than those who reported none, and the more active men ages 30-49 years and active women ages 20-39 had significantly higher values (p < 0.05). When HDL cholesterol was adjusted for age, body mass index, alcohol use, cigarette smoking and interclinic population variation, more active men (47.1 vs 45.2 mg/dl; p = 0.0001) and more active women (59.6 vs 57.7 mg/dl; p = 0.02) had higher HDL cholesterol levels than their sedentary counterparts. Thus, the association between HDL cholesterol and reported physical activity was, at least in part, independent of other factors that influence HDL cholesterol concentration, but was not associated with exercise tolerance as determined by treadmill exercise testing.