Efficacy of Berberine in Patients with Type 2 Diabetes
Abstract
Berberine has been shown to regulate glucose and lipid metabolism in vitro and in vivo. This pilot study was to determine the efficacy and safety of berberine in the treatment of type 2 diabetic patients. In study A, 36 adults with newly diagnosed type 2 diabetes were randomly assigned to treatment with berberine or metformin (0.5 g t.i.d.) in a 3-month trial. The hypoglycemic effect of berberine was similar to that of metformin. Significant decreases in hemoglobin A1c (HbA1c; from 9.5% ± 0.5% to 7.5% ± 0.4%, P<0.01), fasting blood glucose (FBG; from 10.6 ± 0.9 mmol/L to 6.9 ± 0.5 mmol/L, P<0.01), postprandial blood glucose (PBG; from 19.8 ± 1.7 to 11.1 ± 0.9 mmol/L, P<0.01) and plasma triglycerides (from 1.13 ± 0.13 mmol/L to 0.89 ± 0.03 mmol/L, P<0.05) were observed in the berberine group. In study B, 48 adults with poorly controlled type 2 diabetes were treated supplemented with berberine in a 3-month trial. Berberine acted by lowering FBG and PBG from one week to the end of the trial. HbA1c decreased from 8.1% ± 0.2% to 7.3% ± 0.3% (P<0.001). Fasting plasma insulin and HOMA-IR were reduced by 28.1% and 44.7% (P<0.001), respectively. Total cholesterol and low-density lipoprotein cholesterol (LDL-C) were decreased significantly as well. During the trial, 20 (34.5%) patients suffered from transient gastrointestinal adverse effects. Functional liver or kidney damages were not observed for all patients. In conclusion, this pilot study indicates that berberine is a potent oral hypoglycemic agent with beneficial effects on lipid metabolism.
1. Introduction
Type 2 diabetes is a worldwide health threat and treatment of this disease is limited by availability of effective medications. All of the existing oral hypoglycemic agents have subsequent failure after long term administration. Thus, new oral medications are needed for long-term control of blood glucose in patients with type 2 diabetes. Certain botanical products from generally regarded as safe (GRAS) plants have been widely used in diabetes care because of their anti-oxidation, anti-inflammation, anti-obesity and anti-hyperglycemia properties.[1, 2]. However, the drawback of using GRAS plants is the difficulty in control their quality as most of these botanical products are mixtures of multiple compounds. Compared to other products from GRAS plants, berberine is a single purified compound, and has glucose-lowering effect in vitro and in vivo [3-6].
Berberine (molecular formula C20H19NO5 and molecular weight of 353.36) is the main active component of an ancient Chinese herb Coptis chinensis French, which has been used to treat diabetes for thousands of years. Berberine is an Over-the-Counter (OTC) drug, which is used to treat gastrointestinal infections in China. Berberine hydrochloride (B·HCl·nH2O) - the most popular form of berberine, is used in this pilot study. The chemical structure of Berberine and related isoquinoline alkaloids are quite different from the commonly used other hypoglycemic agents, such as sulphonylureas, biguanides, thiazolidinediones, or acarbose. Hence, if the efficacy and safety of berberine are confirmed, it can serve as a new class of anti-diabetic medication.
This pilot study was to assess the efficacy of berberine in human subjects with type 2 diabetes. Berberine was given to both newly diagnosed diabetic patients and poorly controlled diabetic patients alone or combination with other hypoglycemic agents for three months. HbA1c, blood glucose and HOMA index were used to determine the efficacy of berberine.
2. Subjects and methods
The subjects were recruited from diabetes outpatient department of Xinhua Hospital by advertising in the clinic. Ninety-seven Chinese volunteers were screened, and 13 subjects were excluded from the study due to failure to meet the recruitment criteria. Thus, 84 subjects (49 women and 35 men) with type 2 diabetes were included in the study. All participants received written and oral information regarding the natural and potential risks of the study and gave their informed consent. The experimental protocol was approved by the ethics committee of Xinhua Hospital. The monotherapy study was designed to compare berberine with metformin (study A, n = 36). The combination therapy was aimed at evaluating additive or synergistic effects of berberine on the classical anti-diabetic agents (study B, n = 48).
Major inclusion criteria were hemoglobin A1c (HbA1c) > 7.0% or fasting blood glucose (FBG) > 7.0 mmol/L, BMI > 22 kg/m2, age 25-75 years, and a negative pregnancy test for female patients. A total of 36 patients who were newly diagnosed for type 2 diabetes were assigned to study A. After a two-month phase during which the patients were treated with diet alone, they were randomly assigned to receive berberine or metformin. A total of 48 type 2 diabetic patients inadequately treated with diet plus sulfonylureas, metformin, acarbose or insulin therapy alone or with a combination were assigned to study B (Table 1). The dose of the medications was stable for at least 2 months before enrollment in the study and remained unchanged throughout the study. All participants were instructed to maintain their lifestyle habits during the course of the study.
Table 1
Subjects (n) | Diet | Sulfonylureas | Metformin | Acarbose | Insulin |
---|---|---|---|---|---|
36 | + | ||||
7 | + | + | |||
3 | + | + | |||
1 | + | + | |||
8 | + | + | |||
12 | + | + | + | ||
9 | + | + | + | ||
4 | + | + | + | ||
1 | + | + | + | ||
1 | + | + | + |
Each study involved a 13-week treatment. For study A, 18 subjects took 500 mg berberine three times daily at the beginning of each major meal or 500 mg metformin three times daily after major meals. For study B, 500 mg berberine three times daily was added to their previous treatment for 3 months. If heavy gastrointestinal side-effects occurred, the dose of berberine was reduced to 300 mg three times daily.
Patients were evaluated weekly for the first 5 weeks of treatment and then every 4 weeks until the end of study. The primary efficacy end point was glycemic control as determined by HbA1c levels. Secondary efficacy parameters included changes in fasting blood glucose (FBG), postprandial blood glucose (PBG), plasma triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) concentrations. Adverse events were recorded throughout the study by direct questioning.
2.1. Measurements
Blood glucose was determined by a glucose oxidase method (Roche, Basel, Switzerland). Serum insulin and C-peptide were determined by radioimmunoassay (Linco Research, St. Charles, MO). HbA1c was analyzed using the high-pressure liquid chromatography (BioRad, Hercules, CA). Plasma triglyceride, total cholesterol, HDL-C, LDL-C, alanine thansaminase (ALT), γ glutamyl transpeptidase (γ-GT) and creatinine concentrations were determined by enzymatic assays (Roche, Basel, Switzerland). The HOMA method was used to compare differences in the profiles for insulin resistance (HOMA-IR) and for β-cell dysfunction (HOMA-β cell) [7]. Ten insulin-treated subjects were excluded from the HOMA analysis.
HOMA-IR = fasting insulin (μU/ml)×fasting glucose (mmol/L)/22.5
HOMA-β cell = [20 − fasting insulin (μU/ml)] / [fasting glucose (mmol/L) - 3.5]
2.2. Statistical analysis
Descriptive statistics and analysis were performed in SPSS 12.0 for Windows. In study A, the significance of the differences between means of metformin and berberine groups was analyzed by Wilcoxon Rank Sum Test. The statistical differences between baseline and endpoint were calculated using Wilcoxon signed rank test. In study B, the significance of the differences among different time points was analyzed by repeated measure ANOVA. The α level was set at 0.05.
3. Results
In study A, 36 patients were included and randomly assigned to metformin or berberine treatment. Three patients of the berberine group and two patients of the metformin group withdrew from the study because of treatment failure. In study B, 48 patients were included, and 5 subjects were excluded from the study before week 13. Among the five subjects, three failed to complete the study in lack of efficacy, one failed in lack of participation time, and one was excluded due to lack of compliance (pill count < 80%). Thus, 74 participants were eligible for the final analysis.
3.1. Berberine verse metformin (study A)
In newly-diagnosed diabetic patients, berberine reduced blood glucose and lipids (Table 2). There were significant decreases in HbA1c (by 2%; P < 0.01), FBG (by 3.8 mmol/L; P < 0.01) and PBG (by 8.8 mmol/L; P < 0.01) in the berberine group. The FBG (or PBG) declined progressively during the berberine treatment, reaching a nadir that was 3.7 mmol/L (or 8.7 mmol/L) below baseline by week 5, and remained at this level until the end of the study (Fig 1A). Triglycerides and total cholesterol decreased by 0.24 mmol/L (P < 0.05) and 0.57 mmol/L (P < 0.05) with berberine treatment. It seemed there was a declining trend of HDL-C and LDL-C; however, no significant differences between week 1 and week 13 were observed in the berberine group. Compared with metformin, berberine exhibited an identical effect in the regulation of glucose metabolism, such as HbA1c, FBG, PBG, fasting insulin and postprandial insulin. In the regulation of lipid metabolism, berberine activity is better than metformin. By week 13, triglycerides and total cholesterol in the berberine group had decreased and were significantly lower than in the metformin group (P<0.05).