GLUCOSE-METABOLISM IN RENAL STONE PATIENTS

The calciuric response and the changes of plasma glucose and insulin p roduced by a 75-gram oral glucose tolerance test were determined in 27 male patients with idiopathic calcium renal stones (6 with dietary hy percalciuria, 5 with nondietary hypercalciuria and 16 with normocalciu ria) and 22 healthy male subjects. The subjects were classified as obe se (greater-than-or-equal-to 120% ideal weight) and nonobese. The inci dence of an abnormal response to glucose loading was similar in the st one patients and the healthy subjects. In addition, the plasma glucose and insulin levels after oral glucose load did not differ between the stone patients and control subjects and were affected by the individu al degree of obesity. Urinary calcium excretion increased significantl y after glucose ingestion in both the stone patients and the control s ubjects. Urinary calcium excretion was greater in the stone patients t han in the control subjects due to the presence of patients with nondi etary hypercalciuria, and the increment in urinary calcium excretion i n the dietary hypercalciuric and normocalciuric stone patients was ind istinguishable from that in the control subjects. The degree of obesit y did not affect the increment in urinary calcium excretion. These res ults suggest that overconsumption of refined carbohydrates such as sug ar-sweetened soft drinks, soda and cakes may be a risk factor for ston e formation, especially in the patients with nondietary hypercalciuria .