Blood glucose replacement rates in normal and diabetic humans

Abstract

The rate of decrease in specific activity of blood glucose following intravenous injection of uniformly C¹⁴–labeled glucose in a series of 13 nondiabetic and 19 diabetic humans was measured over periods of 3—6 hr. In the nondiabetic humans the specific activity decreased exponentially for about 3 hr, then usually slowed down gradually over the next 3 hr. From the curves obtained up to 3 hr, rates of blood glucose replacement were estimated to be 120 mg/kg/hr, with a range of from 84 to 153 mg/kg/hr. The high and fluctuating blood glucose levels of the diabetic subjects made estimations of replacement rate somewhat uncertain, but despite a wider spread of values, the average, at 109 mg/kg/hr, was not markedly different from that of the nondiabetic subjects. Mild diabetics on the whole had a lower replacement rate, whereas severe diabetics had a markedly higher replacement rate than the normal subjects. The proportion of blood glucose carbon appearing in the respiratory CO₂ was also similar—in nondiabetics, 25±3%, and in diabetics, 22 ± 5%. Despite the higher glucose pool in the diabetics, the glucose spaces were about the same at 30 ± 5% and 29 ± 3%, respectively. Taking into consideration a glucose utilization rate by brain of 60—70 mg/kg/hr, the turnover data indicate that relatively little of the glucose which enters the blood in the fasting human is used by the peripheral musculature. Submitted on November 25, 1960