Study examines the effects of ginkgo leaf extract on patients diagnosed with type 2 diabetes during an 8 week treatment period.
Li XS, Zheng WY, Lou SX, Lu XW, Ye SH. Effect of Ginkgo leaf extract on vascular endothelial function in patients with early stage diabetic nephropathy. Chin J Integr Med. 2009;15(1):26-29.
Randomized, open clinical trial conducted in China
64 patients diagnosed with type 2 diabetes and were classified as early-stage diabetic nephropathy (DN). Both treatment groups were well matched at baseline for fasting blood glucose (FBG) and serum creatinine indexes and educated to follow a high-quality, low-protein diet. Excluded were patients with other known factors that could induce proteinuria; those having received nephro-toxic drugs; patients with ketoacidosis, hepatic or hemopoietic primary diseases, or psychiatric diseases; and pregnant or lactating women.
Patients were randomized equally into two groups: treatment and control. All were treated for 8 weeks with conventional therapy for diabetes, but the treatment group also received ginkgo leaf extract (GLE) tablets 3 times per day (providing 57.6 mg/day of flavone glycosides and 14.4 mg/day of terpene lactones).
To explore the effect of GLE on vascular endothelial function (VEF) in patients with early stage diabetic nephropathy (DN).
The brachial arterial endothelium dependent dilating function (EDDF) in the treated group increased significantly in response to experimentally induced congestion, yet ginkgo did not change the vascular dilation when nitroglycerin was administered. The plasma levels of VEF-related factors like the von Willebrand Factor (vWF) decreased, and nitric oxide (NO) increased in the treatment group. Urinary albumin excretion rates and serum creatinine were markedly lowered after treatment in the ginkgo group, showing statistical significance. These indexes were not significantly changed in the control group after treatment. The difference in FBG between before and after treatment in the two groups was insignificant.
Previous studies have found that GLE could improve the structure and function of the kidney in rats with type 2 diabetes mellitus and that the efficacy of GLE in combination with Western medical treatment was found to be better than that of Western medicine alone in patients with diabetic nephropathy.1,2
This study using oral doses of standardized GLE in humans is another step toward an understanding of the mechanisms by which GLE may work in improving circulatory integrity. Brachial arterial inner diameter (BAID) dilation in response to induced congestion and the lack of response to nitroglycerin suggest that ginkgo may act to improve VEF via endothelial-dependent mechanisms without having any direct effect on smooth muscle–dependent factors.
Elevated levels of the serum glycoprotein vWF are found in people who have had ischemic stroke due to blood clots. The decrease in vWF in the ginkgo treatment group suggests that an antithrombotic action might be one of the mechanisms contributed by ginkgo in preventing and treating diabetic vascular complications, which is yet awaiting further research.
The reduction in the excretion of urinary albumin in the ginkgo group certainly indicates an improvement in glomerular filtration.
The reduction in the excretion of urinary albumin in the ginkgo group certainly indicates an improvement in glomerular filtration. Combined with the additional evidence of a positive effect on VEF in patients with early stage DN, this study appears to offer good rationale for the use of standardized ginkgo in slowing or preventing the development of microangiopathies of early stage DN.