Co-occurrence of hypercalciuria and hypouricaemia in type 2 diabetic patients

The relationship between the urinary excretion of calcium (Ca2+) and uric acid was investigated in 151 Type 2 diabetic patients and 48 normal subjects. In the diabetic patients, uric acid clearance/creatinine clearance (Clurate/Clcr) was higher and the serum level of uric acid was lower than in the normal subjects (Clurate/Clcr: 10.9 +/- 5.8 vs 8.1 +/- 2.6%, p less than 0.001; serum uric acid: 3.4 +/- 86 vs 357 +/- 89 mumol l-1, p less than 0.001). Calcium clearance/Clcr (Clca/Clcr) also increased in the diabetic patients, as did urinary excretion rate, but the serum Ca2+ level was not different to normal control subjects (Clca/Clcr: 2.29 +/- 1.59 vs 1.56 +/- 0.98%, p less than 0.001; Ca2+ excretion rate: 2.24 +/- 1.67 vs 1.63 +/- 1.11 mmol day-1, p less than 0.01; serum Ca2+ level: 2.34 +/- 0.11 vs 2.33 +/- 0.08 mmol l-1). In the diabetic patients, Clcr positively and the serum uric acid negatively correlated with the urinary excretion of Ca2+ (p less than 0.001 for both correlations in the multivariate regression analysis). These data suggest that the diabetic patients have increased fractional excretion of both Ca2+ and uric acid.