Complementary and Alternative Medicine Therapies for Diabetes: A Clinical Review
1. Gurjeet S. Birdee, MD, MPH and
2. Gloria Yeh, MD, MPH
Complementary and alternative medicine (CAM) refers to a wide range of clinical therapies outside of conventional medicine.1 The term “complementary” refers to therapies that are used in conjunction with conventional medicine, whereas “alternative” medicine includes therapies that are used in place of conventional medicine. The term “integrative” medicine has been advocated by some CAM providers and researchers as representing a combination of conventional medicine, CAM, and evidence-based medicine.2
The National Center for Complementary and Alternative Medicine, a federal scientific agency for CAM research, categorizes CAM into five domains: biologically based practices, mind-body medicine, manipulation and body-based practices, energy medicine, and whole-medical systems (Table 1). Biologically based practices and mind-body medicine are the most common CAM modalities used and studied for the treatment of diabetes in the West and are the focus of this review.
In the United States, CAM is frequently used by adults, with 40% reporting use in the past 12 months.3 An estimated 34% of adults with diabetes use some type of CAM therapy.4 The estimated out-of-pocket expense in 2007 on CAM therapies was $44 billion.5
Although some CAM therapies have been shown to affect glycemic control, the clinical efficacy and mechanism of many CAM therapies for diabetes is controversial, and safety issues are a concern. Adverse effects of many CAM therapies are not well documented. Because patients with diabetes often take multiple prescription medications, there exists the potential for herb-drug and herb-dietary supplement interactions, leading to adverse events.6,7 At least 63% of the general population do not disclose use of CAM therapies to their physicians.8
The purpose of this clinical review is to discuss selected CAM therapies frequently used for patients with diabetes and to provide a framework to advise patients on CAM use.
Biologically Based Practices: Herbs and Supplements
More than one-third of patients with diabetes in the United States use some type of complementary and alternative medicine (CAM). Herbs, dietary supplements, and mind-body medicine are the most commonly used and studied CAM modalities to treat diabetes. This article provides an overview of CAM for diabetes, including proposed mechanisms, a summary of evidence, and adverse effects. It also offers recommendations for counseling patients regarding CAM use.
Definition, regulation, and safety
In 1994, the Dietary Supplement Health and Education Act (DSHEA), approved by the U.S. Congress, defined dietary supplements as products taken by mouth that contain vitamins, minerals, herbs, or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandular substances, and metabolites. Supplements can take different forms, including tablets, capsules, soft gels, gel capsules, liquids, or powders.
Importantly, DSHEA treats dietary supplements as a type of food rather than as drugs. Under this bill, dietary supplements do not need U.S. Food and Drug Administration (FDA) approval before marketing, and manufacturers are not mandated to establish the quality, efficacy, or safety of products. Manufacturers cannot make specific clinical claims that supplements can treat or cure a specific condition. However, nonspecific statements are allowed, such as proclamations that the product “supports,” “promotes,” or “enhances” specific organ systems. For example, a supplement manufacturer cannot state on the product label that the substance “reduces blood glucose in patients with diabetes,” but may state that the product “supports glucose tolerance.”
After marketing, the FDA is responsible for determining whether dietary supplements are “unsafe.” In 2007, the FDA established a new set of regulations called Good Manufacturing Practices to improve the quality of dietary supplements by requiring the industry to appropriately label and ensure the purity, strength, and composition of all dietary supplements. These regulations are scheduled to be phased in by this year. Therefore, their successful implementation cannot yet be evaluated.