CAM SUPPLEMENTS USED FOR DIABETES AND ITS COMPLICATIONS
Although there are hundreds of different botanical and nonbotanical products to treat diabetes and its complications, this book will focus on some of the most well-known and commonly used products, roughly in order of popularity. A discussion of botanical or dietary sources, chemical constituents and mechanism of action, adverse effects and drug interactions, examples of the types of clinical studies that evaluate these substances, and an overall summary will be presented for each product.
Botanical biological complementary therapies used to lower blood glucose include cinnamon (Cinnamomum cassia), gymnema (Gymnema sylvestre R.Br.), fenugreek (Trigonella foenum-graecum), bitter melon (Momordica charantia), ginseng (Panax ginseng or Panax quinquefolius L.), nopal (Opuntia streptacantha), aloe (Aloe vera L.), banaba (Lagerstroemia speciosa L.), caiapo (Ipomoea batatas), ivy gourd (Coccinia indica), holy basil (Ocimum sanctum), Vijayasar (Pterocarpus marsupium Roxb. [Leguminoceae]), jambolan (Eugenia jambolana), blonde psyllium (Plantago ovata), glucomannan (Amorphophallus konjac K. Koch), guar gum (Cyamopsis tetragonolobus [L.] Taub), stevia (Stevia rebaudiana Bertoni), pine bark (Pinus pinaster), and tea (Camellia sinensis), which may include green, oolong, or black tea. Claims have been made for bilberry (Vaccinium myrtillus) and milk thistle (Silybum marianum), but there is less evidence for these and other products.
Nonbotanical biological complementary supplements that may lower blood glucose include chromium, vanadium, nicotinamide, magnesium, and coenzyme Q10.
Botanical and nonbotanical products thought to decrease the complications of diabetes include the vitamin-like substance alpha-lipoic acid, vitamin E, gamma-linolenic acid, ginkgo (Ginkgo biloba L.), fish oil, policosanol (Saccharum officinarum L.), garlic (Allium sativum), guggul (Commiphora mukul), and red yeast rice (Monascus purpureus Went). Another biological complementary product frequently used is St. John’s wort (Hypericum perforatum L.), which is used to treat some types of depression rather than diabetes. However, depression frequently occurs in diabetes patients and many clinicians consider this a complication of diabetes.
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Botanical CAM Supplements to Treat Diabetes
CAM supplements of botanical origin have been used to treat diabetes for many centuries. Although some products were once common only in certain parts of the world, their use has now become more mainstream. Many of the products originated in Asia and India and with time have been adopted in Europe and other parts of the Western world. Interest in the use of these substances has increased, and many have been evaluated in studies. This chapter will provide an overview of many of the botanical products used to treat diabetes. Table 1 (on page 75) provides a brief summary of the information in this section.
CINNAMON (Cinnamomum cassia)
Cinnamon is one of many complementary and alternative medicine (CAM) supplements that have been used to treat diabetes. It is one of several dietary supplements that fall under the legislation of the Dietary Supplement Health and Education Act of 1994.4 Although cinnamon bark and cinnamon flower are used medicinally, Chinese cinnamon, or Cinnamomum aromaticum (synonym C. cassia), is the form used for diabetes. This product is also known as cassia.63 Cinnamon comes from an evergreen tree that grows over 20 feet (up to 7 meters) high and has a white aromatic bark and angular branches. It has leaves about 7 inches (18 cm) long and small yellow flowers that bloom in early summer. The tree grows in tropical climates, and the bark is removed in short lengths and dried.63
Cinnamon has been used for type 2 diabetes and for gastrointestinal complaints such as dyspepsia or flatulence. Cinnamon is a popular flavoring agent in different foods and beverages and is a common ingredient in chewing gum, toothpaste, mouthwash, and other products.19
Chemical Constituents and Mechanism of Action
The active ingredient is thought to be hydroxychalcone, a polyphenolic polymer that may enhance the effect of insulin. Specifically, it may work on insulin receptors to increase insulin sensitivity, promote cell and tissue glucose uptake, and promote glycogen synthesis.64
Adverse Effects and Drug Interactions
Adverse effects include irritation or contact dermatitis, if used topically.62 Allergic reactions may also occur. There are no reported drug interactions. In theory, cinnamon may lower blood glucose if combined with secretagogues such as sulfonylureas or insulin.
Clinical Studies
A study in Pakistan in 60 individuals with type 2 diabetes who were taking sulfonylureas found that cinnamon improved glucose and lipids.65 Patients were given 1, 3, or 6 g/day cinnamon or placebo for 40 days. Fasting blood glucose declined by 18–29% after 40 days in all three groups. At a dose of 1 g/day, glucose decreased from a baseline of 209 mg/dl (11.6 mmol/l) to 157 mg/dl (8.7 mmol/l); at 3 g/day, glucose decreased from 205 mg/dl (11.4 mmol/l) to 169 mg/dl (9.4 mmol/l); and at 6 g/day, glucose decreased from 234 mg/dl (13.0 mmol/l) to 166 mg/dl (9.2 mmol/l) (P < 0.05 for all three groups vs. baseline). Cinnamon was withheld for the next 20 days, and fasting glucose was still lower than at baseline, indicating that cinnamon had a sustained benefit. Improvements in lipids were also significant. Total cholesterol decreased by 12–26%, triglycerides decreased by 23–30%, and LDL cholesterol also declined by 7–27% (P < 0.05 for all three parameters). HDL cholesterol did not improve, and the authors did not report changes in A1C.
Another study was done in Germany in 79 individuals with type 2 diabetes being treated with oral agents or diet.66 This 4-month randomized double-blind, placebo-controlled trial evaluated use of an aqueous cinnamon extract, essentially devoid of coumarins (<0.1%) and thought to be less allergenic than other forms. Patients were randomized to a placebo or a capsule containing 1 g cinnamon three times a day. In the cinnamon group, mean baseline fasting glucose decreased from 167 mg/dl (9.3 mmol/l) to 147 mg/dl (8.2 mmol/l) after 4 months (P < 0.001). The placebo group had a decrease from mean baseline of 156 mg/dl (8.7 mmol/l) to 150 mg/dl (8.3 mmol/l; results not significant). The mean percentage difference was 10.3% in the treatment group and 3.37% in the placebo group (P = 0.046). Mean baseline A1C did not decrease significantly.