Biliary lipid and bile acid composition in insulin-dependent diabetes mellitus. Arguments for increased intestinal bacterial bile acid degradation.

Bile cholesterol saturation and bile acid composition was studied in 12 nonobese male insulin-dependent diabetics and 28 controls. The total bile lipid concentration in the bile rich duodenal aspirate was lower in the diabetics. The bile cholesterol saturation index was lower in the diabetics if calculated according to Thomas and Hofmann, but not if calculated according to Carey's critical tables. A negative correlation was observed between the cholesterol saturation index of the bile of the diabetics and their long-term metabolic control, as measured by the percentage HbA1c. No correlation existed between the saturation index and the metabolic control at the time of bile sampling as measured by serum glucose, beta-hydroxybutyrate, free fatty acids, and triglycerides. There was also a negative correlation between the cholesterol saturation index and the serum cholesterol concentrations. The glycine-taurine ratio of the conjugated bile acids was increased in the diabetics, as was the percentage concentration of secondary bile acids (deoxycholic acid and lithocholic acid). No correlation was found between the metabolic control of the diabetic state and either the glycine-taurine ratio or the percent concentration of secondary bile acids. These results do not favor a higher incidence of cholesterol gallstones in male juvenile-onset insulin-dependent diabetics. The increased glycine-taurine ratio of the conjugated bile acids and the elevated concentration of secondary bile acids may be due to increased bacterial invasion of the small intestine or decreased absorption of bile acids in the terminal ileum in these insulin-dependent diabetics.