donderdag 23 mei 2013

Gynostemma and diabetes

Gynostemma Extract Shows Benefits as an Adjunct Therapy for Treatment of Type 2 Diabetes 
Huyen VTT, Phan DV, Thang P, Ky PT, Hoa NK, Ostenson CG. Antidiabetic effects of add-on Gynostemma pentaphyllum extract therapy with sulfonylureas in type 2 diabetic patients. Evid Based Complement Alternat Med. 2012;2012:452313. doi: 10.1155/2012/452313.

Jiaogulan bij Ruhlemans
Sulfonylureas (SUs) are a class of antidiabetic drugs. They are often used with other drugs because monotherapies are often insufficient in providing normal blood sugar levels in patients with type 2 diabetes over the long term. The authors report that in their country, Vietnam, herbs are often used to manage diabetes. In an earlier study, they demonstrated an antidiabetic effect of gynostemma (GP; Gynostemma pentaphyllum) extract in newly diagnosed patients with diabetes.1 In the study reported here, they investigated the antidiabetic effects and safety of add-on GP extract therapy with an SU in a randomized, double-blind, placebo-controlled trial in patients with type 2 diabetes who had not been previously treated with antidiabetic drugs.

To be included, participants had to have newly diagnosed type 2 diabetes and be 40 to 70 years of age. Having never used antidiabetic drugs, the participants had to have a mean fasting plasma glucose (FPG) measurement from 9 mmol/L to 14 mmol/L and a glycosylated hemoglobin (HbA1c) value from 9% to 13%. They were recruited at the National Institute of Gerontology and 2 district hospitals in Hanoi, Vietnam.

At baseline, 25 participants provided a detailed medical history and underwent a physical examination and fasting and oral glucose tolerance tests. Blood was drawn to measure HbA1c, liver and renal function, fasting lipids, and C-peptide levels. After screening, the participants received 30 mg of a gliclazide modified-release preparation as a single daily dose during a 4-week run-in period. Gliclazide is a commonly prescribed SU.

After the 4-week SU treatment, the patients were instructed to continue the gliclazide and were randomly assigned into either group A (GP extract, n=12) or group B (placebo, n=13). The add-on GP extract was provided at a dose of 6 g daily (3 g twice daily). Whole plants were collected and authenticated. Plants were boiled in water, and ethanol was added to precipitate impurities and then removed by distillation (ethanol) and filtration (impurities). The remaining brown powder contained approximately 5% flavonoids and 18% saponins. The placebo extract was green tea (Camellia sinensis) that was supplied at the same dose and it was similar to the GP extract in packaging.

The patients were instructed to follow a diet recommended for newly diagnosed type 2 diabetics and to walk 30 minutes daily at least 5 days a week. Blood samples were collected every 2 weeks for 12 weeks.

Primary outcomes were FPG and HbA1c, homeostasis model assessment of insulin resistance (HOMA-IR), and HOMA of beta-cell function (HOMA-β). Secondary outcomes were body mass index (BMI), weight, waist circumference, blood pressure, changes in blood lipids and liver enzymes, serum creatinine, and urea.

The authors report that after the 4-week run-in period with SU treatment, the FPG of all participants decreased from 11.4 ± 1.3 mmol/L to 9.3 ± 1.3 mmol/L
In the GP extract group, FPG was not significantly different after 4 weeks with the add-on GP extract therapy, but it was significantly decreased after 6 weeks of add-on GP extract therapy
The HbA1c values decreased from 9.0 ± 0.7% to 7.0 ± 0.7% in the GP extract group, and from 8.8 ± 0.6% to 8.1 ± 0.6% in the placebo group; a significant difference between groups (P=0.001). Therapy with GP extract also significantly reduced the 30- and 120-minute oral glucose tolerance test postload values

These results demonstrate improved glycemic control in patients treated with an SU plus GP extract, as compared to patients treated with the SU alone. Because the patients in both groups had similar diet and exercise regimens, the GP extract, and not diet and exercise, appeared to be mainly responsible for the improved glycemic control, say the authors. The glycemic control effect of the combined SU/GP extract therapy was comparable with that of an SU combined with metformin reported in an earlier prospective diabetes study.2 "Our results could offer an alternative to addition of other oral medication to treat type 2 diabetic patients using traditional Vietnamese medicine," write the authors.

References
1Oppel-Sutter M. Antidiabetic effect of gynostemma tea in type 2 diabetes. HerbClip. January 31, 2011 (No. 081064-417). Austin, TX: American Botanical Council. Review of Antidiabetic effect of Gynostemma pentaphyllum tea in randomly assigned type 2 diabetic patients by Huyen VTT, Phan DV, Thang P, Hoa NK, Ostenson CG. Horm Metab Res. May 2010;42(5):353-357.

2Hanefeld M, Brunetti P, Schernthaner GH, Matthews DR, Charbonnel BH; on behalf of the QUARTET Study Group. One-year glycemic control with a sulfonylurea plus pioglitazone versus a sulfonylurea plus metformin in patients with type 2 diabetes. Diabetes Care. 2004;27(1):141-147. 

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