Table 1—— Controlled clinical trials of single herbs for glycemic control*

Herb/Supplement Reference Design Sample Intervention Control Outcomes Evidence Direction Jadad Adverse Effects/Events
Allium sativum (Garlic) Sitprija S et al (1987) Double-blind; 2 parallel groups 33 Type 2; diet alone Garlic; 700 mg/d (preparation unspecified); for 4 wks Placebo No change in FBG, PPG; insulin – 2 No side effects; no effect on liver function

Aloe vera Bunyapraphatsara N et al (1996) Non-randomized; Single-blind; 2 parallel groups 76 Type 2; uncontrolled on OHA Aloe vera Linn. 80% juice; 1 tbsp BID (prepared by Faculty of Pharmacy, Mahidol University, Thailand); for 42 d Placebo juice Decrease FBG + N/A No effects on liver/kidney function
Aloe vera Yongchaiyudha S et al (1996) Non-randomized; Single-blind; 2 parallel groups 40 Type 2; newly diagnosed Aloe vera Linn. 80% juice; 1 tbsp BID (prepared by Faculty of Pharmacy, Mahidol University, Thailand); for 42 d Placebo juice Decrease FBG + N/A 1/40 ketosis (group not reported)

Artocarpus heterophyllus Fernando MR et al (1991){dagger} Non-randomized; Open-label; Crossover; Short-term metabolic trial 10 Type 2; no diabetes medication Artocarpus heterophyllus; 200mg fresh leaves boiled decoction; single experimental dose prior to GTT Distilled water Decrease PPG + N/A Not reported
Asteracanthus longifolia Fernando MR et al (1991){dagger} Non-randomized; Open-label; Crossover; Short-term metabolic trial 10 Type 2; no diabetes medication Asteracanthus longifolia; 100mg fresh leaves boiled decoction; single experimental dose prior to GTT Distilled water Decrease PPG + N/A Not reported

Bauhinia forficata Russo EMK et al (1990) Double-blind; Crossover 16 Type 2; diet and/or OHA Bauhinia forficata tea; 3g/d (1g individual tea bags from dried leaves); for 8 wks Placebo herb tea (sape, Imperata brasiliensis) No change in FBG, HgbA1C, insulin - 3 No side effects; no effect on liver/kidney function

Coccinia indica Azad Khan AK et al (1979) Double-blind; 2 parallel groups 32 Type 2; uncontrolled or untreated Coccinia indica leaf; 1800 mg/d (freeze-dried powder from fresh leaves in tablets); for 6 wks Placebo tablet Decrease FBG, PPG ++ 4 No side effects; no effect on liver/kidney function
Coccinia indica Kamble SM et al (1996) Non-randomized; Open-label; 3 parallel groups 70 Type 2; other medications unclear Coccinia indica; 6g/d (dried pellets from fresh leaves); for 12 wks No treatment; OHA Decrease FBG, PPG (similar to OHA) ++ N/A Not reported

Ficus carica (Fig leaf) Serraclara A et al (1998) Open-label; Crossover 10 Type 1; diet and insulin Fig leaf tea; 13g/d leaf decoction; for 4 wks Bitter commercial tea blend Decrease PPG, insulin requirement; no change in FPG, C peptide, HgbA1C + 2 No side effects

Ginseng (Unspecified) Sotaniemi EA et al (1995) Double-blind; 3 parallel groups 36 Type 2; newly diagnosed; diet alone Ginseng; 100mg/d vs. 200mg/d (tablet preparation Dansk Droge, Copenhagen); for 8 wks Placebo tablet Decrease FBG, HgbA1C (200mg); no change in BG, insulin, C-peptide during GTT + 3 No side effects
Ginseng (American) Panax quinquefolius Vuksan V et al (2000) Single-blind; Multiple crossover; Short-term metabolic trial 10 Type 2; diet and/or OHA Ground root of American Ginseng; 3g vs 6g vs 9g capsules (Chai-Na-Ta Corp, British Columbia); single experimental dose at varying times prior to GTT Identical placebo capsule containing corn flour Decrease PPG (all doses), no difference between doses or administration times + 3 No side effects
Ginseng (American) Panax quinquefolius Vuksan V et al (2000) Single-blind; Multiple crossover; Short-term metabolic trial 9 Type 2; well-controlled on diet and/or OHA Ground root of American Ginseng; 3g capsule (Chai-Na-Ta Corp, British Columbia); single experimental dose at varying times prior to GTT Identical placebo capsule containing corn flour Decrease PPG (given at 0, -40min) + 2 Mild insomnia (1/9)
Ginseng (American) Panax quinquefolius Vuksan V et al (2001) Double-blind; Crossover 24 Type 2; diet and/or OHA American Ginseng extract; 3g/d (standardized extract, Chai-Na-Ta Corp, British Columbia); for 8 wks Placebo capsule Decrease HgbA1C, FBG; no change insulin ++ 2 No effect on liver/kidney function

Gymnema sylvestre Baskaran K et al (1990) Non-randomized; Open-label; 2 parallel groups 47 Type 2; all on OHA Gymnema sylvestre extract, GS4; 400 mg/d capsule; for 18–20 mos No GS4 treatment Decrease FBG, HgbA1C, glycosylated plasma protein, conventional medication, urine glucose; increase insulin ++ N/A Not reported
Gymnema sylvestre Shanmugasundaram ERB et al (1990) Non-randomized; Open-label; 2 parallel groups 64 Type 1; all on insulin Gymnema sylvestre extract, GS4; 400 mg/d capsule; for 2–30 mos No GS4 treatment Decrease FBG, HgbA1C, glycosylated plasma protein, insulin requirement, urine glucose; increase C-peptide ++ N/A No side effects

Momordica charantia Welhinda J et al (1986) Non-randomized; Open-label; Crossover; Short-term metabolic trial 18 Type 2; newly diagnosed Momordica charantia juice; homemade preparation (dose unspecified); single experimental dose prior to GTT Distilled water Decrease PPG + N/A Not reported
Momordica charantia, V-insulin Baldwa VS et al (1977) Non-randomized; Blinding unclear; 2 parallel groups; Short-term metabolic trial 9 DM (?6 Type 1, 3 Type 2); all on insulin/OHA stopped during study Momordica charantia vegetable insulin (purified protein extract); single severity dependent experimental dose (subcutaneous) Placebo injection (unspecified) Decrease FBG + N/A No hyper-sensitivity reactions

Myrcia uniflora Russo EMK et al (1990) Double-blind; Crossover 18 Type 2; on diet and/or OHA Myrcia uniflora tea; 3g/d (1g individual tea bags from dried leaves); for 8 wks Placebo herb tea (sape, Imperata brasiliensis) No change in FBG, HgbA1C; decrease insulin - 3 No side effects; no effect on liver/kidney function

Ocimum sanctum (Holy basil) Agrawal P et al (1996) Single-blind; Crossover 40 Type 2; on diet and/or OHA Ocimum album fresh leaf; 2.5g powder; for 4 wks Fresh spinach leaf powder Decrease FBG, PPG, urine glucose ++ 2 No side effects
Opuntia streptacantha (Nopal) Frati AC et al (1990) Open-label; Crossover; Short-term metabolic trial 14 Type 2; diet and/or OHA (diet alone during study) Grilled nopal stems; 500g; single experimental dose 400ml H2O Decrease glucose, insulin ++ 1 Not reported
Opuntia streptacantha (Nopal) Frati-Munari AC et al (1988) Non-randomized; Open-label; Crossover; Short-term metabolic trial 32 Type 2; OHA stopped during study Fresh nopal stems, broiled; 500g crude weight; single experimental dose Water; broiled zucchini squash Decrease FBG, insulin ++ N/A Not reported

Silymarin (Milk Thistle) Velussi M et al (1997) Open-label; 2 parallel groups 60 Type 2 with cirrhosis; diet and insulin Silymarin; 600mg/d ("Legalon" formulation, IBI Lorenzini, Milan); for 12 mos No treatment Decrease FBG, mean BG, urine glucose, HgbA1C, fasting insulin, insulin requirement, C peptide ++ 2 No side effects

Trigonella foenum (Fenugreek) Sharma RD et al (1990) Blinding unclear; Crossover 15 Type 2; diet and OHA (dose decreased 20% during study) Defatted fenugreek seed powder; 100g/day in unleavened bread; for 10 d No treatment Decrease FBG, PPG, postprandial insulin, urine glucose ++ 1 Not reported
Trigonella foenum (Fenugreek) Sharma RD et al (1990) Blinding unclear; Crossover 5 Type 2; diet and OHA (dose decreased 20% during study) Defatted fenugreek seed powder; 100g/day in unleavened bread; for 20d No treatment Decrease FBG, PPG, urine glucose, insulin ++ 1 Not reported
Trigonella foenum (Fenugreek) Sharma RD et al (1990) Blinding unclear; Crossover 10 Type 1; diet and insulin (dose decreased during study) Defatted debitterised fenugreek seed powder; 100g/d in unleavened bread; for 10d No treatment Decrease FBG, PPG, urine glucose; no change body weight, insulin ++ 1 Not reported
Trigonella foenum (Fenugreek) Madar Z et al (1988) Non-randomized; Open-label; Crossover; Short-term metabolic trial 21 Type 2 Fenugreek seed powder; 15g in water; single experimental dose with meal tolerance test No treatment Decrease PPG; no change in insulin + N/A No side effects

* 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.

{dagger} Fernando MR, Wickramasinghe N, Thabrew MI, Ariyananda PL, Karunanayake EH: Effect of Artocarpus heterophyllus and Asteracantha longifolia on glucose tolerance in normal human subjects and in maturity-onset diabetic patients. J Ethnopharmacol 31:277–277, 1991