Vol. 17 • Issue 6 • Page 43
Healthcare providers can no longer use tradition or clinical experience alone to guide clinical care decisions. Evidenced-based practice involves integrating research findings, clinical expertise and patient preferences.1 The treatment of type 2 diabetes is complex. Therefore, it is vital for nurse practitioners to use evidence-based practice guidelines to effectively manage the disease.
Type 2 diabetes is one of the most prevalent disorders treated in primary care settings today. The Centers for Disease Control and Prevention (CDC) estimates that 23.6 million (7.8%) U.S. residents now have diabetes.2 The increasing prevalence and severity of diabetes make it essential to explore ways to improve treatment plans.
Clinical Question to Be Explored
The American Association of Clinical Endocrinologists (AACE) recommends initial monotherapy for patients with type 2 diabetes who are naïve to pharmacologic therapy and have HbA1c levels of 6% to 7%.3The AACE recommends combination therapy when HbA1c levels are 7% to 8%.3
Metformin is traditionally regarded as first-line therapy for type 2 diabetes when monotherapy is appropriate. As a result of the progressive nature of diabetes, other agents are added over the course of the disease process.4
Because aggressive treatment to achieve glycemic control decreases microvascular complications in newly diagnosed patients with type 2 diabetes, initial treatment with combination therapy rather than metformin alone may lead to better overall outcomes.5This practice should decrease healthcare spending on vascular and neuropathic complications.5Therefore, the question to be examined is: "What is the best practice for initial glucose control in patients with type 2 diabetes?"
Evidence-based practice involves developing a clinical question, gathering pertinent evidence, critically appraising the evidence, incorporating evidence with clinical expertise and patient preferences, and evaluating the practice decision or change.1
We began exploration of our question with a thorough review of the literature. We reviewed data obtained from meta-analyses and clinical practice guidelines.1We searched multiple databases and guideline sources, including CINAHL, Health Source, Medline, the Cochrane Database of Systematic Reviews and the National Guideline Clearinghouse.
Review and Evaluation of Literature
As understanding of type 2 diabetes has progressed, therapy has moved from a focus on monotherapy toward combination approaches.6 lthough monotherapy can delay the progression of diabetes, it does not prevent disease progression. Studies have shown that combination therapy is more effective for the prevention of disease progression because it addresses both insulin resistance and beta cell dysfunction.7The following paragraphs summarize some of this research.
A 24-week randomized, double-blind, placebo-controlled parallel group study enrolled 1,091 patients with type 2 diabetes and HbA1c levels of 7.5% to 11%.8The study sought to assess the efficacy of initial combination therapy with sitagliptin (Januvia) and metformin (Glucophage). Participants were randomized to one of six daily treatments as follows:
• sitagliptin 100 mg, metformin 1,000 mg
• sitagliptin 100 mg, metformin 2,000 mg
• metformin 1,000 mg
• metformin 2,000 mg
• sitagliptin 100 mg
• placebo.
The mean baseline HbAsub>1cof patients in all groups was 8.8%. Researchers documented a significant decrease in HbAsub>1cfrom baseline in the group treated with sitagliptin 100 mg and metformin 2,000 mg (see table). Of note, the incidence of hypoglycemia did not increase with combination therapy vs. metformin alone.8A meta-analysis of nine studies demonstrated the benefits of sitagliptin as monotherapy and as an adjunct to other oral diabetes medications, including metformin, pioglitizone (Actos), rosiglitizone (Avandia) and glipizide (Glucotrol). In all studies, sitagliptin provided favorable outcomes in the management of glycemic control, as evidenced by decreased plasma glucose levels or decreased HbA1c evels.9
wo of the studies demonstrated significant benefits of treatment with metformin and sitagliptin combination therapy. Results of the first study, which involved 24 patients, demonstrated a decrease in fasting glucose of 23.8 mg/dL with combination therapy compared with a decrease of 3.4 mg/dL with metformin alone. In the second study, which involved 701 patients, addition of sitagliptin to metformin resulted in a 25.4 mg/dL reduction in fasting plasma glucose and a 50.6 mg/dL decrease in 2-hour postprandial glucose. Sitagliptin also contributed to improved pancreatic beta cell function in the patients. It did not promote adverse effects such as weight gain and hypoglycemia, which are common with other drug therapies.9 In sum, combination therapy with metformin and sitagliptin provided significantly improved control of type 2 diabetes as evidenced by decreased HbA1c and blood glucose levels. The complementary actions of these two agents provided additive effects that improved glycemic control, helping to prevent disease progression and subsequent microvascular and macrovascular complications. In addition, the incidence of adverse effects was no greater with combination therapy than with metformin alone.
Recommendation for Policy
In response to current research findings, AACE recommendations and clinical experience, we recommend early intervention with combination therapy over metformin alone for patients whose HbA1c is higher than 7%. The evidence shows that initiation of combination therapy in patients with HbA1c levels greater than 7% improves glycemic control, which slows disease progression and helps prevent microvascular and macrovascular complications.
We chose to focus on combination therapy with sitagliptin and metformin because of their very different but complementary pharmacologic profiles. However, when initiating any drug therapy, individualize the drugs used in combination therapy according to the characteristics and needs of each patient.
Putting It Into Practice
For implementation of change in treatment approach to be successful, the first step is to emphasize the need for better glycemic control. Due to the increasingprevalence of type 2 diabetes and its subsequent complications, nurse practitioners are aware of the urgency to intervene with more aggressive therapy. Now we must emphasize this urgency to patients to promote adherence to a change in medication therapy.
Considering that diabetes is one of the most common diseases treated in primary care, NPs should be more vigilant about staying current with evidence-based research about this condition. This can be accomplished through frequent review of the literature, including guidelines from diabetes-focused groups such as the AACE. Sharing relevant findings and individual clinical experiences with colleagues will create a clear vision for implementing strategies for change.1 Communication between NPs and patients is vital to promoting change. Sharing real-life examples of treatment success empowers patients to take an active role in managing their disease. Ongoing support will encourage the patient to persist in achieving treatment goals.
References
1. Melnyk B, Fineout-Overholt E. Evidenced-Based Practice in Nursing and Healthcare. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2005.
2. Centers for Disease Control and Prevention. National diabetes fact sheet: general information and national estimates on diabetes in the United States. Atlanta, Ga.: U.S. Department of Health and Human Services; 2005.
3. Rodbard HW, et al. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the management of diabetes mellitus. Endocr Pract. 2007;13(Suppl 1):1-68.
4. Uphold R, Graham M. Clinical Guidelines in Family Practice. 4thed. Gainesville, Fla.: Barmarrae Books; 2003.
5. Krentz A, Bailey C. Oral antidiabetic agents: current role in type 2 diabetes mellitus. Drugs. 2005;65(3):385-411.
6. McDonnell M. Combination therapy with new targets in type 2 diabetes; a review of available agents with a focus on pre-exercise adjustment. J Cardiopulm Rehabil Prev. 2007;27(4):193-201.
7. LaSalle J, Cross L. Oral combination therapy with thiazolidinediones in type 2 diabetes. Am J Manag Care. 2006;12(14 Suppl):S369-S381.
8. Goldstein B, et al. Effect of initial combination therapy with sitagliptin, a dipeptidyl peptidase-4 inhibitor, and metformin on glycemic control in patients with type 2 diabetes. Diabetes Care. 2007;30(8):1979-1987.
9. Schlesselman L. Sitagliptin, the first dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes. Formulary. 2006;41:434-441.
Kayla Henson is a family nurse practitioner at Regional Medical Associates in Draffenville, Ky. Rita Hight is a family nurse practitioner at Princeton Family Care in Princeton, Ky. Donna Welborn is a family nurse practitioner at Fairview Community Health Center in Morgantown, Ky. Sheryl Wyatt is a family nurse practitioner at Purchase Cancer Group in Paducah, Ky.
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