Reviewed: Lain R, Gangway L, Chen X, et al. Chinese herbal medicine Tianqi reduces progression from impaired glucose tolerance to diabetes: a double-blind, randomized, placebo-controlled, multicenter trial [published online January 16, 2014]. J Clin Endocrinol Metab. doi: 10.1210/jc.2013-3276.

One of the primary precursors to type 2 diabetes (T2DM) is impaired glucose tolerance (IGT). People with IGT also may be at greater risk for cardiovascular disease. Restoring glucose tolerance could reduce this risk and improve health in general. The mixture of traditional Chinese medicinal herbs known as Tianqi (consisting of Astragalus spp., Fabaceae; Coptis spp., Ranunculaceae; Trichosanthes spp., Cucurbitaceae; Ligustrum spp., Oleaceae; Dendrobium spp., Orchidaceae; Panax spp., Araliaceae; Lycium spp., Solanaceae; Eclipta spp., Asteraceae; Rhus spp., Anacardiaceae; and Cornus spp., Cornaceae) includes several botanicals shown to have anti-hyperglycemic activity. This 11-center, double-blind, randomized, placebo-controlled trial investigated the effects of Tianqi in patients with IGT.

Included patients were between 25 and 70 years of age diagnosed with IGT (not controlled with pharmaceuticals) who had not participated in a clinical trial for three months prior to the study. Patients were excluded if they had cardiovascular disease; experienced a heart attack in the six months preceding the study; had “severe” stress or hyperglycemia; deviated from the study protocol; had mental health disorders; were pregnant, lactating, intending to become pregnant, or not using contraception; or were allergic to Tianqi. Other exclusion criteria were systolic blood pressure (SBP) ≥ 160 mmHg, diastolic blood pressure (DBP) ≥ 100 mmHg, total cholesterol ≥ 6.22 mmol/L, or low-density lipoprotein (LDL) cholesterol ≥ 4.14 mmol/L.

From the 804 patients who were screened, 480 were enrolled in the study, and 420 patients met the inclusion criteria and were randomized to the Tianqi group (n=210) or the placebo group (n=210). All patients received lifestyle counseling consisting of diet information provided by a nutritionist and were requested to maintain their routine physical activity. Counseling occurred at baseline and at three, six, and nine months. Three times per day prior to meals, patients took five capsules (total 4.8 g/day) of Tianqi or placebo (sugarless starch and iron oxide) for 12 months. Both the Tianqi and placebo were provided by Heilongjiang Baoquan Pharmaceutical Co. (Heilongjiang, China). The Tianqi was characterized by ultra-performance liquid chromatography-tandem mass spectrometry. Levels of magnoflorine, berberine, gallic acid, astragaloside IV, palmitic acid, and ginsenosides were used as quality control markers. The contents of the eight compounds in the capsules were determined using standard curves of corresponding standards.

The oral glucose tolerance test (OGTT) was employed to measure IGT at baseline and every three months throughout the trial. The primary outcome was the diagnosis of progression to T2DM. Additionally, weight, body mass index (BMI), metabolic parameters, and liver and kidney function also were determined. The occurrence of adverse effects (AEs), their severity, and progression were recorded.

Of the 420 randomized subjects, 198 in the Tianqi group and 191 in the placebo group finished the study. Reasons for patient dropouts included loss to follow-up (28), AEs (2), and deviation from inclusion criteria (1). Although there were no significant differences in patient metabolic parameters between the two groups at baseline, the majority of the patients had high concentrations of triglycerides, total cholesterol, and LDL.

At the trial’s completion, a significantly greater number of patients in the placebo group had progressed to T2DM as compared to the Tianqi group (56 vs. 36, respectively; P=0.01). Also, a significantly greater number of patients in the Tianqi group had normal glucose tolerance (NGT) in comparison to the placebo group (125 vs. 89, respectively; P=0.001). The risk of developing T2DM in those consuming Tianqi was reduced by 32.1% as compared to placebo. The progression to T2DM was 13.79-25% in the Tianqi group and 26.67-35.71% in the placebo group at the end of the study. Alternately, those with NGT ranged from 56.25-68.97% in the Tianqi group and 42.8-50% in the placebo group. After the final patient finished the study, 50 patients in the Tianqi group had T2DM, and 67 patients in the placebo group had T2DM. Additionally, 71 patients in each group still had IGT.

Of all patients, 15 in the Tianqi group and 11 in the placebo group reported AEs. All of the AEs were considered mild and consisted of gastrointestinal complaints, rash, tinnitus, genital swelling, and high concentrations of urinary protein.

In summary, the calculated risk reduction experienced by those in the Tianqi group was similar to that offered by standard pharmaceutical treatments for T2DM. The authors conclude that Tianqi might be a useful treatment to prevent the progression from IGT to T2DM, especially in regions of the world accustomed to the use of botanical medicines. According to the authors, limitations of this trial include the length of the study, relatively small sample size, and the lack of assessment of insulin or glycated hemoglobin concentrations. Overall, this study suggests that Tianqi is well tolerated and efficacious in reducing the risk of T2DM in high-risk populations.

—Amy C. Keller, PhD