The study follows a smaller one earlier this year that also provided evidence of the product's benefit on certain parameters of type 2 diabetes.
Incidence of type 2 diabetes has grown rapidly in recent years and is set to be one of the major chronic diseases of the future, increasing in conjunction with both obesity and ageing populations.
But while foods that can help control the condition are expected to become increasingly profitable for industry, there is as yet little scientific evidence to support the role of supplements or functional foods for this purpose.
The new trial, published in the 8 October issue of Life Sciences (75(21):2505-13), found that 77 type 2 diabetes patients who continued to take their anti-diabetic medication further lowered blood sugar levels and increased cardiovascular function after supplementing with Pycnogenol, an extract of the bark of the Maritime pine that grows along the coast of southwest France.
In the double-blind, placebo-controlled study, the patients took 100 mg of Pycnogenol for 12 weeks at the same time as a standard anti-diabetic treatment.
"Supplementation of Pycnogenol to conventional diabetes treatment lowers glucose levels and improves endothelial function," reported the team from the Guang An Men Hospital of Chinese Medical Science Research Institute in Beijing.
There are currently more than 194 million people with diabetes worldwide but if nothing is done to slow the epidemic, the number will exceed 333 million by 2025, according to the International Diabetes Federation.
In the UK the number of people with diabetes has surged to 1.8 million (3 per cent of the population), increasing by 400,000 in just eight years, according to new figures this month. Most of these -1.5 million - are suffering from type 2 diabetes, and a further million are likely to have the condition without being diagnosed yet, said Diabetes UK.
A collection of factors influenced by diet such as obesity, blood fat levels and raised blood pressure are thought to be involved in the onset of type 2 diabetes but evidence for the right kind of diet to reverse such risk factors is still lacking, according to experts.
Dr Michael Quon, chief of the diabetes unit of the US National Center for Complementary and Alternative Medicine (NCCAM) told NutraIngredients.com earlier this year that there are some foods and nutrients, such as dark chocolate and magnesium, that warrant further investigation in this area.
Dark chocolate has been shown to improve blood flow and it is thought that Pycnogenol has a similar effect. Blood vessels are generally more constricted in diabetic people, often causing poor circulation. Pycnogenol, a potent antioxidant because of its high content of procyanidins and bioflavonoids, supports mechanisms that lead to better blood flow.