Rationale and design of a clinical trial to evaluate metformin and colesevelam HCl as first-line therapy in type 2 diabetes and colesevelam HCl in prediabetes

Effect of colesevelam and niacin on low-density lipoprotein cholesterol and glycemic control in subjects with dyslipidemia and impaired fasting glucose

BACKGROUND

Niacin monotherapy in patients with dyslipidemia and impaired fasting glucose (IFG) may result in hyperglycemia. Colesevelam has the unique dual approvals to lower low-density lipoprotein cholesterol (LDL-C) and to improve glycemic control in type 2 diabetes mellitus.

OBJECTIVES

The aim of our study was to evaluate the effect of combined colesevelam and niacin treatment on LDL-C-lowering and glycemic control in subjects with IFG and dyslipidemia.

METHODS

Men or women ≥ 18 years of age, with dyslipidemia (non-high-density lipoprotein cholesterol ≥ 100 mg/dL and ≤ 220 mg/dL; high-density lipoprotein cholesterol < 60 mg/dL) and fasting plasma glucose (FPG) ≥ 90 mg/dL and ≤ 145 mg/dL were randomly assigned 1:1 to colesevelam (3750 mg/d) with niacin titration (n = 70) or placebo with niacin titration (n = 70) over 12 weeks. Niacin was titrated from 500 mg/d up to a maximum of 2000 mg/d as tolerated, and all subjects took enteric-coated aspirin daily. Lipid and glycemic efficacy parameters were assessed as well as safety evaluations of adverse events, vital signs, alanine aminotransferase, aspartate aminotransferase, hematology, and urinalysis.

RESULTS

Adjunct colesevelam had significantly greater LDL-C-lowering effect than niacin alone (placebo); -20.67% vs -12.86%, respectively (P = .0088). Niacin-mediated increases in FPG were significantly less with adjunct colesevelam (1.8 mg/dL vs 6.7 mg/dL; P = .0046), and fewer colesevelam subjects had increases of ≥ 10 mg/dL in FPG (8 vs 17, respectively). Adjunct colesevelam resulted in significantly smaller increases in hemoglobin A1c than placebo (0.06% vs 0.18%, respectively; P = .005). Consistent with hemoglobin A1c and FPG changes, fructosamine levels significantly decreased with colesevelam treatment (-5.0 μmol/L) but increased with placebo (3.0 μmol/L; P =.0255).

CONCLUSIONS

Colesevelam as an adjunct to niacin therapy further lowers LDL-C while obviating the adverse effects of niacin on glucose metabolism in patients with dyslipidemia and IFG.

Colesevelam improved lipoprotein particle subclasses in patients with prediabetes and primary hyperlipidaemia

BACKGROUND

A randomised, double-blind, placebo-controlled study evaluated lipid- and glucose-lowering effects of colesevelam in patients with prediabetes and primary hyperlipidaemia. We report the effect of colesevelam on lipoprotein particle concentration and particle size (determined by nuclear magnetic resonance spectroscopy) in these patients.

METHODS

Adults with prediabetes (World Health Organization criteria), low-density lipoprotein cholesterol (LDL-C) ≥ 100 mg/dL (≥2.6 mmol/L) and triglycerides < 500 mg/dL (<5.6 mmol/L) were randomised to colesevelam 3.75 g/day or placebo for 16 weeks. The intent-to-treat population comprised 103 colesevelam and 106 placebo recipients.

RESULTS

At the end of the study, mean reduction from baseline in total LDL particle concentration was significantly greater with colesevelam versus placebo (mean treatment difference: -113 nmol/L; p = 0.02). Increases in total very low-density lipoprotein particle concentration (VLDL-P) and high-density lipoprotein particle concentration (HDL-P) did not differ significantly between the groups; however, with colesevelam versus placebo, there were significantly (p < 0.05) greater increases in large and medium VLDL-P and large HDL-P and reductions in small VLDL-P. Mean size increases were significantly greater with colesevelam for VLDL (mean treatment difference: 5.3 nm; p < 0.0001) and HDL (0.1 nm; p = 0.002).

CONCLUSIONS

Colesevelam improved the overall atherogenic lipoprotein profile in adults with prediabetes and primary hyperlipidaemia, despite potentially less favourable changes in VLDL particles.

Initial combination therapy with metformin plus colesevelam in drug-naïve Hispanic patients with early type 2 diabetes

OBJECTIVE

To evaluate initial combination therapy with metformin plus colesevelam in drug-naïve Hispanic patients with type 2 diabetes mellitus.

RESEARCH DESIGN AND METHODS

Patients self-identified as Hispanic from a previous study were included in this exploratory post hoc analysis. Patients were randomized to metformin plus colesevelam or metformin plus placebo. The primary efficacy parameter was the mean change in glycated hemoglobin (HbA1c) levels from baseline.

RESULTS

Metformin plus colesevelam had a greater mean HbA1c reduction (-1.2 ± 0.1%) than metformin plus placebo (-0.8 ± 0.1%; P = 0.001) from mean baselines of 7.7% and 7.6%, respectively. Low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol, total cholesterol, and apolipoprotein (apo) B levels were also reduced (P < 0.0001 for all), while triglyceride (P < 0.0001) and apoA-I (P < 0.05) levels were increased with metformin plus colesevelam treatment compared with metformin plus placebo. With metformin plus colesevelam versus metformin plus placebo, more patients achieved an HbA1c of < 7.0% (75% vs 56%) and LDL-C of < 100 mg/dL (49% vs 14%; both P < 0.05).

CONCLUSION

Metformin plus colesevelam may be an effective initial treatment option for Hispanic patients with early type 2 diabetes mellitus.

Novel therapeutics and targets for the treatment of diabetes

The microvascular complications of insufficiently controlled diabetes (neuropathy, retinopathy and nephropathy) and the marked increased risk of macrovascular events (e.g., stroke and myocardial infarction) have a dire impact on society in both human and economic terms. In Type 1 diabetes total β-cell loss occurs. In Type 2 diabetes, partial β-cell loss occurs before diagnosis, and the progressive β-cell loss during the life of the patient increases the severity of the disease. In patients with diabetes, increased insulin resistance in the muscle and liver are key pathophysiologic defects. In addition, defects in metabolic processes in the fat, GI tract, brain, pancreatic α-cells and kidney are detrimental to the overall health of the patient. This review addresses novel therapies for these deficiencies in clinical and preclinical evaluation, emphasizing their potential to address glucose homeostasis, β-cell mass and function, and the comorbidities of cardiovascular disease and obesity.

TGR5 potentiates GLP-1 secretion in response to anionic exchange resins

Anionic exchange resins are bona fide cholesterol-lowering agents with glycemia lowering actions in diabetic patients. Potentiation of intestinal GLP-1 secretion has been proposed to contribute to the glycemia lowering effect of these non-systemic drugs. Here, we show that resin exposure enhances GLP-1 secretion and improves glycemic control in diet-induced animal models of “diabesity”, effects which are critically dependent on TGR5, a G protein-coupled receptor that is activated by bile acids. We identified the colon as a major source of GLP-1 secretion after resin treatment. Furthermore, we demonstrate that the boost in GLP-1 release by resins is due to both enhanced TGR5-dependent production of the precursor transcript of GLP-1 as well as to the local enrichment of TGR5 agonists in the colon. Thus, TGR5 represents an essential component in the pathway mediating the enhanced GLP-1 release in response to anionic exchange resins.

Initial combination therapy with metformin plus colesevelam improves lipoprotein particles in patients with early type 2 diabetes mellitus

BACKGROUND

The bile acid sequestrant colesevelam has been shown to significantly reduce low-density lipoprotein particle concentration (LDL-P) in adults with primary hyperlipidemia or type 2 diabetes mellitus (T2DM).

OBJECTIVE

To assess the effect of initial combination therapy with metformin plus colesevelam on lipoprotein particles in patients with T2DM (secondary efficacy variables).

METHODS

This 16-week, randomized, double-blind, placebo-controlled study enrolled drug-naïve adults with T2DM, glycated hemoglobin 6.5%-10.0%, low-density lipoprotein cholesterol (LDL-C) ≥100 mg/dL, and triglycerides <500 mg/dL. Patients were randomized 1:1 to either open-label metformin (titrated to 1700 mg/day) plus double-blind colesevelam 3.75 g/day or open-label metformin plus double-blind placebo.

RESULTS

In total, 286 patients were randomized (metformin plus colesevelam [n = 145]; metformin plus placebo [n = 141]). Compared with metformin plus placebo, the combination of metformin plus colesevelam significantly reduced LDL-C (mean treatment difference: -16.3%), total cholesterol (-6.1%), non-high-density lipoprotein cholesterol (-8.3%), and apolipoprotein (apo) B (-8.0%) and significantly increased triglycerides (median treatment difference: 18.6%) and apoA-I (mean treatment difference: 4.4%; all P < .001). Metformin plus colesevelam significantly reduced total LDL-P (mean treatment difference: absolute change -186 nmol/L [percent change -11.7%]; both P < .0001), largely attributable to a reduction in small LDL-P, and increased total very-low-density lipoprotein particle concentration (mean treatment difference: absolute change 6 nmol/L; P = .03 [percent change 8.3%; P = .06]) and total high-density lipoprotein particle concentration (1.0 μmol/L; P = .03 [4.5%; P = .01]) versus metformin plus placebo.

CONCLUSION

Initial combination therapy with metformin plus colesevelam improved the atherogenic lipoprotein profile of patients with early T2DM by significantly reducing LDL-P. ClinicalTrials.gov identifier: NCT00570739.

Colesevelam hydrochloride to treat hypercholesterolemia and improve glycemia in prediabetes: a randomized, prospective study

OBJECTIVE

To assess the effect of the bile acid sequestrant colesevelam hydrochloride in patients with hypercholesterolemia and prediabetes.

METHODS

In this 16-week, randomized, double-blind study, adults with untreated prediabetes (2-hour postoral glucose tolerance test [OGTT] glucose > or =140 to 199 mg/dL, fasting plasma glucose [FPG] > or =110 to 125 mg/dL, or both), low-density lipoprotein cholesterol (LDL-C) > or =100 mg/dL, and triglycerides <500 mg/dL were randomly assigned to receive colesevelam (3.75 g/d) or placebo. The primary end point was percent change in LDL-C from baseline to week 16 with last observation carried forward. Secondary end points included change in FPG, hemoglobin A1c (A1C), and 2-hour post-OGTT glucose level from baseline to week 16 and attainment of LDL-C and FPG targets.

RESULTS

In total, 216 patients were randomized (colesevelam, 108; placebo, 108). In comparison with placebo, colesevelam significantly reduced LDL-C (mean treatment difference, -15.6%), non-high-density lipoprotein cholesterol (-9.1%), total cholesterol (-7.2%), apolipoprotein B (-8.1%) (P<.001 for all the foregoing), FPG (median, -2.0 mg/dL; P = .02), and A1C (mean, -0.10%; P = .02). Colesevelam did not significantly change 2-hour post-OGTT glucose (-1.9 mg/dL; P = .75) or high-density lipoprotein cholesterol (-0.5%; P = .80). In addition, colesevelam significantly increased triglyceride levels relative to placebo (median, 14.3%; P<.001). The proportion of patients achieving target levels with colesevelam versus placebo, respectively, was as follows: LDL-C <100 mg/dL (29% versus 11%; P<.001), A1C <6.0% (37% versus 25%; P = .05), FPG <110 mg/dL (48% versus 56%; P = .97), and normalization of glucose (FPG <100 mg/dL [40% versus 23%; P = .06]). Colesevelam had a weight-neutral effect and was well tolerated.

CONCLUSION

Colesevelam is an option for managing the lipid profile and normalizing glucose levels in patients with hypercholesterolemia and prediabetes. Further study is warranted to determine whether colesevelam slows or prevents progression of prediabetes to type 2 diabetes.

Colesevelam: an improved bile acid sequestrant for treating hypercholesterolemia and improving diabetes

There is a well-established association between serum cholesterol and coronary heart disease. Statins are the first-line agents for the treatment of hypercholesterolemia, yet combination therapy is required to achieve the desired reduction in low-density lipoprotein cholesterol (LDL-C). Niacin and bile acid sequestrants were among the first lipid-lowering drugs developed to lower LDL-C and have been established to be effective both in monotherapy and in combination therapy. However, tolerability and compliance issues have limited their use. Colesevelam HCl is the newest bile acid sequestrant and reduces LDL-C by 16-22% in monotherapy and adds 12-14% in combination dual therapy with statins, fibrates and ezetimibe or in triple therapy with statin and ezetimibe. It reduces C-reactive protein levels by 16-19% in monotherapy or by 23% in combination with statins and other lipid-lowering therapies. In addition, it consistently reduces hemoglobin A_1c by 0.5% in addition to other hypoglycemic drugs in studies of patients with diabetes. Compared with other bile acid sequestrants it has a higher bile acid-binding capacity, reduced adverse effects and, therefore, has better compliance. Colesevelam HCl is thus a useful addition to the lipid-lowering formulary as a second-line agent, particularly for patients with metabolic syndrome requiring extra reduction in LDL-C.

The Role of Colesevelam Hydrochloride in Hypercholesterolemia and Type 2 Diabetes Mellitus

Objective:

To evaluate the safety and efficacy of colesevelam hydrochloride for the treatment of hypercholesterolemia and type 2 diabetes mellitus.

Data Sources:

Literature retrieval was accessed through MEDLINE/PubMed (1950–March 2010), Web of Science (1980–March 2010), and International Pharmaceutical Abstracts (1977–March 2010) using the terms colesevelam, dyslipidemia, hypercholesterolemia, and type 2 diabetes mellitus. References from publications identified were reviewed for additional resources. In addition, abstracts presented at the most recent (2009) American Diabetes Association, American Association of Clinical Endocrinologists, and European Association for the Study of Diabetes annual meetings were searched for relevant original research.

Study Selection and Data Extraction:

All articles in English identified from the data sources were evaluated. All relevant studies evaluating the safety and efficacy of colesevelam in hypercholesterolemia and/or type 2 diabetes mellitus were included. Priority was placed on data obtained from human randomized controlled trials.

Data Synthesis:

Seventeen clinical trials were reviewed and evaluated. Of the clinical trials evaluating colesevelam in hypercholesterolemia, 3 evaluated monotherapy, 4 evaluated combination therapy with hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, and 6 evaluated combination therapy with other lipid-lowering therapies. In the type 2 diabetes mellitus trials, colesevelam was evaluated in combination with metformin, sulfonylureas, insulin, and rosiglitazone and sitagliptin. A review of the clinical trials provided evidence that colesevelam monotherapy effectively reduces low-density lipoprotein cholesterol (LDL-C). Additionally, the use of colesevelam in combination with other lipid-lowering therapies further reduces LDL-C. Colesevelam also effectively reduces hemoglobin A1c in patients with type 2 diabetes mellitus. The safety and tolerability of colesevelam appear to be improved from that of older-generation bile acid sequestrants, with adverse effects similar to those with placebo in monotherapy and type 2 diabetes mellitus trials.

Conclusions:

Colesevelam is a safe and effective option for the treatment of hypercholesterolemia and type 2 diabetes mellitus. It can fulfill a useful role in combination with HMG-CoA reductase inhibitors for hypercholesterolemia and should be considered in patients with type 2 diabetes mellitus with concomitant hypercholesterolemia.

Advances in the treatment of prediabetes

Type 2 diabetes mellitus (T2DM) is epidemic in most developed and many developing countries. Owing to the associated morbidity, mortality and high costs of care, T2DM is an important global public health challenge and target for prevention. Patients at high risk for T2DM (referred to as having prediabetes) can be easily identified based on fasting glucose levels or responses to an oral glucose tolerance test (OGTT). More recently, glycosylated hemoglobin (i.e. HbA1c, which is also termed A1C in the US) has also been introduced as a diagnostic tool for both prediabetes and diabetes. Such patients are also at risk for cardiovascular disease (CVD). Since obesity and physical inactivity are important risk factors for T2DM, lifestyle interventions, emphasizing modest weight loss and increases in physical activity, should be recommended for most patients with prediabetes. Such interventions are safe and effective and also reduce risk factors for CVD. A number of oral antidiabetic agents have been shown to be effective at delaying onset of T2DM in patients with prediabetes. Thiazolidinediones (TZDs) are the most effective, reducing incident diabetes by up to 80%. Metformin, acarbose and orlistat also reduce incident diabetes, but their efficacy is much lower than the TZDs. Pharmacologic interventions may be appropriate for patients at particular risk for developing diabetes, but the benefits of treatment need to be balanced against the safety and tolerability of the intervention. If pharmacologic treatment is warranted, metformin should be considered first because of its favorable overall safety, tolerability, efficacy and cost profile.