Among patients with type 2 diabetes, more severe disease, as measured by glycemic control and insulin resistance, is associated with an elevated risk of kidney stones, researchers reported online ahead of print in European Urology.

Aviva E. Weinberg, MD, of Stanford University School of Medicine in Palo Alto, Calif., and colleagues analyzed data from adult participants in the 2007-2010 National Health and Nutrition Examination Survey (NHANES). A self-reported history of type 2 diabetes and history of insulin use were associated with a 2.4 times and 3.3 times increased risk of kidney stones disease, respectively.

In a fully adjusted model, individuals with fasting plasma glucose (FPG) levels greater than 126 mg/dL (diabetes) had a 28% increased risk compared with those who had a FPG below 100 mg/dL in a fully adjusted model. Subjects with HbA1c values of 5.7%-6.4% and higher than 6.5% had a 34% and 92% increased risk.

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Insulin resistance, as estimated using fasting plasma insulin (FPI) levels and the homeostasis model assessment of insulin resistance (HOMA-IR) definition, was associated with an increased risk of kidney stone disease. Compared with patients in the lowest FPI tertile and lowest HOMA-IR tertile, those in the highest tertiles had a 28% and 51% increased risk, respectively.

A history of type 2 diabetes, insulin use, FPI, and HbA1c remained significantly associated with kidney stone disease after adjusting for patient factors.

The researchers said their analysis suggests that glycemic control is associated with the pathogenesis of stone disease. “Hyperglycemia and its resultant glycosuria have been implicated in altered renal handling of calcium, phosphorus, and uric acid,” they noted, adding that studies have demonstrated an increase in urinary calcium and phosphorus excretion in patients with type 2 diabetes.

In addition, recent studies have shown that stone formers with type 2 diabetes have increased urinary oxalate excretion, Dr. Weinberg’s group observed. “Both hyperoxaluria and hypercalciuria resulting from poor glycemic control may lead, therefore, to the formation of calcium oxalate stones,” they wrote. Furthermore, they pointed out that uric acid has been found as the main component of stones in a significantly higher proportion of patients with type 2 diabetes.