The metabolic effect of dodecanedioic acid infusion in non-insulin-dependent diabetic patients

Dodecanedioic acid (C12) is an even-numbered dicarboxylic acid (DA). Dicarboxylic acids are water-soluble substances with a metabolic pathway intermediate to those of lipids and carbohydrates. Previous studies showed that contrary to other DAs, very low amounts of C12 are lost with urine. The effects of 46.6 mmol of C12 intravenous infusion for 195 min on blood glucose levels were investigated in five patients with non-insulin-dependent diabetes mellitus (NIDDM), with a good metabolic compensation, and in five healthy volunteers matched for gender, age, and body mass index. Blood samples were taken every 15 min for a period of 360 min to measure glucose, insulin, C-peptide, ketone bodies, and free fatty acid (FFA) levels, and 24-h urine samples were collected to measure C12 and urea excretion. Plasma and urinary C12 concentrations were determined by high-pressure liquid chromatography (HPLC). Indirect calorimetry was continuously performed both basally and during the study period. The average 24-h urinary excretion of C12 was 6.5% versus 6.7% of the administered dose, respectively, in NIDDM patients and in healthy controls. The area under the curve (AUC) values of plasma C12 were 279.9 +/- 42.7 mumol in NIDDM patients and 219.7 +/- 14.0 mumol in controls (P = ns). Plasma glucose levels significantly decreased in NIDDM patients during C12 infusion (from 7.8 +/- 0.6 to 5.4 +/- 0.8 mM at the end of the study period, P < 0.05). Lactate plasma concentration decreased in NIDDM patients from 3.5 +/- 0.2 to 1.5 +/- 0.1 mM (P < 0.001), whereas blood pyruvate increased at the end of the experimental session from 26.0 +/- 11.6 to 99.5 +/- 14.9 microM (P < 0.01). Free fatty acids decreased in diabetic patients from the beginning until the end of C12 infusion, although this difference did not reach statistical significance. No significant increase was found between basal and final values in VO2 consumption and in the values of nonprotein respiratory quotient in both groups of subjects examined. The experimental data indicate that C12 infusion decreases plasma glucose levels in NIDDM patients to normal range without influencing plasma insulin levels. The balance between pyruvate and lactate was affected by C12 infusion only in diabetics patients. C12 might represent a fuel substrate immediately available for tissue energy requirements, especially in conditions such as diabetes mellitus in which glucose metabolism is impaired.