Abstract
In recent years, dietary fibers (unabsorbable plant polysaccharides) have been used successfully in the treatment of diabetics and have also been shown to exert a hypocholesterolemic action. We therefore investigated the influence of glucomannan (prepared from tubers of Amorphophallus Konjac) on the glucose and lipid metabolism of diabetics, and the effects on glucose tolerance of two dietary fibers (glucomannan and guar gum) were compared.
During 50 g oral glucose tolerance tests (OGTT), the peaks in the blood glucose and serum insulin concentrations were slightly delayed and reduced by the addition of 2.6 g glucomannan, both in 5 healthy men and in 10 diabetics. This suggested that the action of glucomannan may delay the absorption of glucose from the small intestinal lumen as do other dietary fibers.
On addition of 2.6 g guar gum, the OGTT results improved in 5 normal subjects, but there was no improvement in 4 diabetics.
The plasma glucagon levels were unchanged during the OGTT on addition of either glucomannan or guar gum, while the plasma gut glucagon levels were slightly suppressed during the OGTT on addition of glucomannan.
When 13 diabetics patients (adult type) had their metabolic ward diets supplemented with 3.9 or 7.8 g glucomannan daily for 90 days, their mean serum cholesterol at 20 days fell by 11.2%(P<0.1) and their mean fasting glucose fell by 29%(P<0.025) for 30 days. The dose of insulin or hypoglycemic agents was therefore reduced or, in some case, withdrawn.
The serum total bile levels were reduced during the OGTT on addition of 2.6 g glucomannan.
It is suggested that the hypocholesterolemic activity of glucomannan may be due to impairment of cholesterol and bile acid absorption from the small intestinal lumen.
We conclude that glucomannan may be a useful agent for the treatment of diabetic patients as well as guar gum and pectin.
