Study Explores Beneficial Effects of Popular Chinese Herbal Formula on Diabetic Retinopathy

Chinese Medicine, both acupuncture and herbal medicine, is used for a wide range of vision issues as well as metabolic/endocrine issues such as diabetes. Commonly treated vision issues range from more mild conditions such as night blindness and range up through potentially complicated issues such as optic nerve atrophy and glaucoma. As far as diabetes goes, there are many potential treatment options which along with diet and lifestyle change can provide positive long-term results.

The treatment of these conditions in Chinese Medicine can be complicated and requires a precise diagnosis from a TCM perspective (see "What Does acupuncture treat?" for more on treating the causes vs. the symptoms). As you are often treating the root of these issues rather than -just- targeting the eye, it is often difficult to describe in western/biochemical terms what you are changing - because so much can be altered at once.

The study I'm exploring today looks at the deeper biochemical effects of a very widely used Chinese herbal formula, Gui Pi Wan (guibi tang, kihi-to) on proliferative retinopathy. Now gui pi wan has a range of uses. The most common of these are those in the anxiety / insomnia spectrum when they arise from what we would call spleen qi and heart blood deficiency in Chinese terms (see "My Heart?" and "My Spleen?" for general info). But as the formula is from the "tonify qi and blood" category, it can be used for deeper pathologies including, but not limited to, a range of metabolic issues including diabetes, various vision issues (the "blood" in Chinese Medicine is part of what keeps the eyes nourished) and issues such as phobias and palpitations.

Researchers using a mouse model of retinal pathogenic neovascularization were looking to understand the preventative effects of gui pi wan on this type of progressive degeneration. They provided a range of protein and vascular analysis to understand these effects and found that the mice that were taking gui pi wan had significantly decreased retinal pathogenic angiogenesis (a slowing of the additional blood vessel growth that leads to blindness in retinopathy patients).

They also saw decreases in PAI-1 protein expression levels. PAI-1 (or plasminogen activator inhibitor-1) is a protein that, when elevated, is a factor for blood clots and arterial plaques among other blood issues. It may be elevated in obese patients, in those with some cancers and in those with metabolic conditions. This decrease in PAI-1 expression noted by the researchers may also help to explain some of the broader effects of gui pi wan with that range of conditions.

Vascular endothelial growth factor (VEGF) is a protein that stimulated blood vessel growth. This is generally elevated in patients with diabetes and is part of the process that stimulates the vascular overgrowth in the retina. Gui pi wan appears to lower the expression of this protein effectively controlling or slowing the degeneration that the overexpression would lead to.

Finally researchers noticed a decrease in fibroblast growth factor 2 (FGF2) which is another marker which appears to play a role in wound healing and heart repair following injury by stimulating the production of new blood vessels (angiogenesis). This function, as with the others, if overexpressed due to continual signaling (likely from diabetes damage), leads to an over proliferation of blood vessels which may result in blindness.

Gui pi wan administration led to significant decreases in all of these important potentiators for blood vessel growth which, when reduced, reduces the likelihood of further damage to the eye.  In clinical practice, while these results are encouraging, it is likely the formula (when properly prescribed and with the right diagnosis) can offer so much more to diabetic patients.  Another recent study and meta-analysis, for example, found that among diabetes and hypertension patients (those conditions tend to co-exist); "the cumulative survival probabilities were higher in CHM users than in non-CHM users."