The plasma levels of four monocarboxylic short-chain fatty acids (SCFA) were determined gas-chromatographically in 10 normal subjects, 27 nontreated diabetics and 15 nontreated hyperthyroidism according to a modification of the methods of Mahadevan et al. The concentrations of acetate and propionate were markedly increased in diabetics. In particular, there was a close correlation between the acetate concentrations and levels of fasting blood sugar. These phenomena are explained on the basis of impaired functions of acetyl-CoA carboxylase (EC 6. 4. 1. 2.) and acetyl-CoA synthetase (EC 6. 2. 1. 1.). It appears likely that such impairments cause under-utilization of active forms of these organic acids and eleveated plasma concentrations of the free acids. The concentrations of isobutyrate and isovalerate were not significantly different among the various experimental groups. Since the origins and physiological significance of these SCFA have not yet been thoroughly elucidated, they require further study in relation to branched-chain amino acids, pyruvate, citrate, lactate and medium-chain fatty acids.
We have reported that glucomannan can be of great benefit in the treatment of diabetics by reducing serum cholesterol levels, decreasing postprandial glycemia, reducing 24-hour urinary glucose and decreasing the dosage of insulin. However, previous studies have suggested that the effects of glucomannan might be greater when it is used in a gelled form. We therefore compared the effects of glucomannan supplements in 50 g OGTT and a test meal in normal subjects. The mean blood glucose and insulin levels with standard OGTT supplemented with 3.9g glucomannan in three different ways (non-gelled, gelled or mixed into glucose solution) were less than those of the standard OGTT. However, there were no significant differences among these groups. On addition of 3.9 g glucomannan to the test meal, glucomannan caused a marked decrease in the mean blood glucose and insulin level compared to the OGTT groups. When 3.9 g glucomannan was incorporated into the food (butter and corn soup), the mean blood glucose and insulin levels were more significantly reduced than those in the case of taking 3.9g glucomannan 15 min before the test meal. It is suggested therefore that glucomannan should be intimately mixed with the food for the management of diabetics as well as guar gum and pectin.