Complementary Medicine and Diabetes: What's Fact, What's Fiction?

AUGUST 01, 2005
Anna D. Garrett, PharmD, BCPS, CPP

Diabetes is spreading throughout the United States, affecting ~16 million people. As obesity rates increase among both adults and children, the numbers are likely to grow in the coming decade. Many patients use complementary medicines (CAM) or nutritional supplements along with their prescription medications for diabetes. Surveys of patients in diabetes clinics indicate that 17% to 66% of people with diabetes use complementary products.1,2 Within specific populations, use is highest among Native Americans, Vietnamese, and Hispanics.3

Scientific literature regarding the efficacy of CAM is lacking. Most of the available data focus on the use of herbs or other dietary supplements, although techniques such as biofeedback, relaxation, yoga, acupuncture, aromatherapy, and traditional Chinese medicine have also been studied. Treatments derived from natural sources have been used for centuries in folk and traditional medicine.

Positive results of small studies using CAM therapies have been reported in the literature. Substances that have been studied (and their reported effects) include3:

  • Fenugreek: decreased fasting blood glucose (FBG) and post-prandial blood glucose (PPG)
  • Ginseng: decreased PPG and HgA1C
  • Cinnamon: decreased serum glucose, total cholesterol, triglycerides, and LDL cholesterol
  • Coccinia indica: decreased FBG, PPG
  • Aloe vera juice: decreased FBG
  • Carnitine: increased glucose uptake and insulin sensitivity
  • Vanadium: decreased FBG, HgA1C, hepatic glucose production, and increased insulin sensitivity
  • Gymnema sylvestre: decreased FBG, HgA1C, urine glucose

Negative results relative to glucose control have been reported for garlic, branched chain amino acids, Bauhinia forficata, and Myrcia uniflora. Conflicting results have been reported in studies using chromium, magnesium, and vitamin E.3

The concurrent use of these preparations with conventional medications raises several issues which should be addressed by health care professionals. First, ~40 % of patients do not tell their providers they are taking these products, which makes it impossible to monitor for drug interactions or side effects.4 Various reasons for not revealing the use of these products range from "no one asked" to the belief that supplements are not medications, and therefore do not need to be reported as such.

This problem is compounded by the fact that information regarding interactions and side effects for many of these products is unavailable because they have not been well studied. Some commonly used herbal supplements, such as St. John's wort and ginseng, have well-described drug interactions, but the majority of supplements have little or no data. Patients may be taking CAM for disease states other than diabetes, which further complicates the obtaining of correct information and evaluating potential problems. Despite the fact that CAM use is widespread, many patients may feel uncomfortable discussing its use. It is important to use nonjudgmental strategies when asking about CAM use, as patients will be more likely to reveal useful information in discussions when they feel they are not being judged.

There are more than 1500 herbal products on the market.5 It is important for CAM users to know that product quality and ingredients vary greatly. Products may contain contaminants or no active ingredients. The FDA does not regulate these products, and there is no required standardization of the active components.

In response to increased use of alternative medicines, the American Diabetes Association issued an update of its position statement on this topic in 2004.6 According to this publication, health care providers need to recognize that use of "unproven therapies" is pervasive, and should ask their patients about the use of alternative medicines. Health care providers should also be able to evaluate the effectiveness of therapies, be aware of potential harm to patients, and acknowledge circumstances in which new or innovative therapeutic measures might be provided to patients (eg, clinical trials).

Pharmacists are in a unique position to help their patients with diabetes make informed decisions about CAM use. The body of knowledge relating to CAM changes constantly, so staying abreast of the latest findings is challenging. Many references, both print and on-line, are available to help caregivers provide reliable information to their patients.

Dr. Garrett is a clinical pharmacist practitioner at Cornerstone Health Care in High Point, NC.

For a list of references, send a stamped, self-addressed envelope to: References Department, Attn. A. Stahl, Pharmacy Times, 241 Forsgate Drive, Jamesburg, NJ 08831; or send an e-mail request to: