Renal hypouricaemia in insulin treated diabetes mellitus

Uric acid metabolism was investigated in 69 insulin-treated male diabetic outpatients and in 23 healthy male subjects, because of a reported coincidence between diabetes and gout. All subjects had normal serum creatinine concentrations and none received diuretic treatments. Compared with normal, the diabetics had significantly lower mean serum uric acid concentrations (0.34 +/- 0.08 (SD) mmol/l versus 0.23 +/- 0.06 mmol/l, p less than 0.001). 17% of the diabetic patients had serum concentrations below the normal mean--2 SD. In contrast, the diabetic patients had a 42% increase in renal uric acid excretion rate (p less than 0.01), and an 83% increase in the ratio of uric acid clearance/creatinine clearance (p less than 0.001). These indices of renal uric acid excretion were both positively correlated to fasting blood glucose levels (r=0.57, p less than 0.001, and r=0.50, p less than 0.001, respectively), to the degree of glycosuria (r=0.73, p less than 0.001, and r=0.63, p less than 0.001, respectively), and to the magnitude of water diuresis (r=0.60, p less than 0.001, and r=0.39, p less than 0.01, respectively). The hypouricaemia observed in these insulin-dependent diabetic male subjects may probably be caused by the increased renal excretion of uric acid in the presence of hyperglycaemia. The study gave no evidence of increased serum uric acid concentrations in insulin-dependent diabetics. It is therefore likely that any coincidence between gout and diabetes derives from other coexisting serum uric acid raising factors.