Diabetes Prevalence is Increasing
Twenty four million Americans - or 8% of the population and nearly 25% of those 60 and older - currently suffer from diabetes according to 2007 prevalence data from the Centers for Disease Control (CDC). The 2007 figure is 3 million higher than 2005 prevalence data. The CDC reported that an additional 57 million had pre-diabetes, a condition that most often precedes a diagnosis of diabetes.
Diabetes can lead to damage of several different tissues, particularly those that are insulin insensitive such as the retina, kidney and nerves. Type 2 diabetes is most common, accounting for 90-95% of all diabetic patients. Both forms cause long-term complications such as neuropathy, nephropathy, cataract and retinopathy. Up to 21% of patients with type 2 diabetes have some signs of retinopathy at time of first diagnosis, and most will develop some degree of retinopathy over time.
The potential role of Pycnogenol (pine bark extract) in the treatment of type 2 diabetes is discussed in a 2008 systematic review
from the Ophthalmic Research Group at Aston University in Birmingham England.Mechanism of Action of Pine Bark Extract
Pycnogenol is the brand name for a standardized extract of bark of the French maritime pine (Pinus pinaster). It contains bioactive procyanidins as does generic standardized pine bark extract. Pine bark extract (hereafter referred to as "Pycnogenol") has been shown to protect endothelial cells against oxidant-induced injury. Pycnogenol promotes a protective antioxidant state by up-regulating important enzymatic and non-enzymatic oxidant scavenging systems. It is a potent natural antioxidant and also has an affinity for proteins such as collagen, which may be responsible for the reduction of pathologically increased capillary permeability observed.
Pycnogenol significantly decreases nitrogen monoxide generation and it is thought that this function may result from a combination of several biological activities including its radical oxygen species and nitrogen monoxide scavenging activity, inhibition of the enzyme nitric oxide syntase (iNOS), and inhibition of iNOS-mRNA expression. Pycnogenol can readily cross the blood-brain barrier to provide antioxidant protection to central nervous system tissue. It is also reported to possess anti-inflammatory action.
Highlighted Clinical Studies
Supplementation of conventional diabetes treatment with 100 mg day) Pycnogenol for 12 weeks has been shown to lower glucose levels, and improve endothelial function (Liu et al., 2004). Glycosylated hemoglobin levels were significantly reduced after 1 month of supplementation. Plasma concentrations of the prostacyclin metabolite, 6-ketoprostaglandin F1, were elevated in both treatment groups, and considerably more pronounced in the Pycnogenol group (p < 0.001).
Pycnogenol is licensed in France for the treatment of diabetic retinopathy. In one investigation, a 6-month double-masked trial of Pycnogenol versus Dexium 500 (calcium dobesilate) was carried out with type 1 and 2 diabetic participants. The pharmacology of Dexium is similar to that of Pycnogenol except that it does not have such a high binding affinity for collagen. Pycnogenol was found to reduce exudates in the eyes of significantly more participants than Dexium. The authors concluded that Pycnogenol might also be beneficial for improvement of visual field loss (Leydhecker, 1986).
Another double-masked, placebo-controlled trial investigated the effect of 150 mg day of Pycnogenol on objective parameters in patients with retinopathies associated with diabetes, atherosclerosis and hypertension (Spadea, 2001). Examination of the ocular fundus showed a significant improvement in those treated with Pycnogenol, as well as improvements in electrophysiology and fluoroangiography measures. The group taking Pycnogenol also experienced a significant reduction in vascular permeability and an improvement in the blood-retinal barrier.
Finally, in a very recent double-blind study
of hypertensive type 2 diabetics taking ACE inhibitors, 125 mg of Pycnogenol for 12 weeks was reported to decrease use of ACE inhibitors by 50%. Fifty eight percent achieved blood pressure control, and LDL levels and fasting blood glucose levels were improved vs. placebo.