Table 2—— Controlled clinical trials of combination herbs for glycemic control*

Herb/Supplement Reference Design Sample Intervention Control Outcomes Evidence Direction Jadad Adverse Effects/Events
Traditional Chinese Medicine (TCM) herb combination Vray M et al (1995) Double-blind; 4 parallel groups 216 Type 2; on diet alone Traditional Chinese herbs; 21 capsules/d (each containing 150mg Coptis Chinensis, 30mg Astragalus membranaceus, 120mg Lonicera Japonica) +/- Oral hypoglycemic (glibenclamide 7.5mg/d); for 3 mos Placebo TCM capsule; Placebo OHA tablet Decrease FBG, decrease PPG, with synergistic effect of both treatments; no change in insulin or HgbA1C + 3 Diarrhea (1), dry mouth (1) TCM treatment; vertigo (1), hypoglycemia (9) OHA treatment; hypoglycemia (10) OHA+TCM
Xiaoke (TCM) Hale PJ et al (1989) Double-blind; Crossover 12 Type 2; on diet and/or OHA Xiaoke tea; uncharacterized herb preparation in 2.72g teabag (Home and Sutton, London), 4 infusions/d; for 4 wks "Ordinary tea" No change in HgbA1C, FBG, PPG, or insulin - 3 No side effects
SPDPA (TCM) formula Xiong M et al (1995) Non-randomized; Open-label; 2 parallel groups 148 Type 2 "Semen Persical Decoction for Purgation with Addition" (Rhubarb, Semen Persical, Ramulus Cinnamomum, Radix Glycyrrhizae, Radix Scrophularie, Radix Rehmanniae, Radix Ophiopogonis, Radix Astragalus); for 2 mos OHA (glyburide) Decrease FBG, but no difference from control + N/A No side effects

Native American herb combination Ryan EA et al (2000) Single-blind; 2 parallel groups 40 Type 2; on diet, OHA, and/or insulin Herbal tea; Unspecified amount, Populus tremuloides (trembling aspen) and Heracleum lanatum (cow parsnip) decoction; 250mL/d; for 10 d Placebo decoction with Chinese green tea, mint, fennel seed No change in PPG, fructosamine, HgbA1C - 2 Minor gastrointestinal discomfort (1)

Tibetan Medicine herb combination Namdul T et al (2001) Open-label; 2 parallel groups 200 Type 2; newly diagnosed or untreated; on diet alone Tibetan medicine herbs; individualized powder/pill combination (at least 2 of 4:Kyura-6, Aru-18, Yungwa-4, Sugmel-19); for 6 mos No herb treatment Decrease FPG, PPG, and GHb; no change in weight ++ 2 Not reported

* All trials are randomized unless otherwise specified in the "Design" column. -, no outcome measures positive; +, at least one outcome measure positive; ++, >50% of outcome measures positive. FBG, fasting blood glucose; PPG, postprandial glucose; OHA, oral hypoglycemic agent.