Role of bicarbonate supplementation on urine uric acid crystals and diabetic tubulopathy in adults with type 1 diabetes

Uricosuria and crystallization are increasingly recognized risk factors for diabetic tubulopathy. This pilot clinical trial aimed to determine the acute effect of urinary alkalinization using oral sodium bicarbonate (NaHCO3) on UA crystals in adults with type 1 diabetes (T1D). Adults with T1D, ages 18 to 65 years (n = 45, 60% female, HbA1c, 7.5 1.2%, 20.2 +/- 9.3 years duration) without chronic kidney disease (eGFR 60 mL/min/1.73 m(2) and albumin-to-creatinine ratio < 30 mg/g) received 2 doses of 1950 mg oral NaHCO3 over 24 hours. Fasting urine and serum were collected pre- and post-intervention. UA crystals were identified under polarized microscopy. Urine measurements included: osmolality, pH, UA, creatinine and kidney injury molecule-1 (KIM-1). NaHCO3 therapy increased mean +/- SD urine pH from 6.1 +/- 0.7 to 6.5 +/- 0.7 (P < .0001). Prior to therapy, 31.0% of participants had UA crystals vs 6.7% post therapy (P = .005). Change in urine pH inversely correlated with change in urine KIM-1 (r:-0.51, P = .0003). In addition, change in urine UA over 24 hours correlated with change in urine KIM-1 (r:0.37, P = .01). In conclusion, oral NaHCO3 normalized urine pH and decreased UA crystals, and may hold promise as an inexpensive and safe tubulo-protective intervention in individuals with T1D.