ACETATE TOLERANCE AND THE KINETICS OF ACETATE UTILIZATION IN DIABETIC AND NONDIABETIC SUBJECTS

We investigated acetate utilization in humans by randomly intravenously infusing acetate (2.5 mmol/min) or bicarbonate (2.8 mmol/min) over 60 min into nine nondiabetic and six non-insulin-dependent diabetic subjects followed with or without bolus intravenous glucose (20 g/m2 body surface area). The acetate metabolic clearance rate (MCR) was greater in the nondiabetic subjects (50.4 ± 14.9 vs 25.0 ± 6.5 mL·min-1·kg-1, p < 0.01) as were acetate elimination rate constant (Kac) (0.031 ± 0.003 vs 0.026 ± 0.004/min, p < 0.01) and basal turnover rate (8.56 ± 3.65 vs 4.92 ± 1.03 μmol·min-1·kg-1, p < 0.01); acetate half-time was thus shorter in the nondiabetics (22.6 ± 2.2 vs 27.2 ± 3.8 min, p < 0.01). Kac was reduced and half-time was prolonged in all the subjects (p < 0.001) when glucose was available. Prior acetate or bicarbonate infusion had no influence on either the KG rate constant of glucose elimination or the postglucose insulin responses in both subject groups. These results suggest that the infused acetate did not worsen glucose tolerance, glucose impaired acetate utilization unlike reported in ruminants, and acetate is rapidly metabolized in humans although at a slower rate in diabetics.