Associations of Insulin Resistance and Glycemic Control with the Risk of Kidney Stones

Objective The associations of insulin resistance and glycemic control with the risk of kidney stones were explored. Methods Generally healthy Japanese (n=2,171) who visited Saiseikai Central Hospital (Tokyo, Japan) for a health check were included in a cross-sectional study. We calculated odds ratios (OR) of having kidney stones in terms of four measures: fasting serum insulin, homeostasis model assessment of insulin resistance (HOMA-IR), fasting plasma glucose (FPG) and glycosylated hemoglobin (HbA1c), adjusting for possible risk factors for kidney stones. Results Fasting serum insulin and HOMA-IR were non-significantly associated with the risk of kidney stones, whereas FPG and HbA1c were significantly associated. Compared with those with an FPG of <100 mg/dL, the ORs in those with an FPG of 100 to <126 mg/dL and >= 126 mg/dL were 1.38 (95% confidence interval [CI] =0.95-2.00) and 1.83 (95% CI =1.09-3.06) (p for trend =0.016). In relation to those with an HbA1c of <5.5%, the ORs in those with an HbA1c of 5.5 to <6.0%, 6.0% to <6.5% and >= 6.5% were 1.16 (95% CI =0.76-1.79), 1.25 (95% CI =0.70-2.23) and 1.98 (95% CI = 1.11-3.52), respectively (p for trend = 0.027). The significant associations between glycemic control measures and the risk of kidney stones were preserved even after the adjustment for factors related to insulin resistance. Conclusion Glycemic control could be an independent risk factor for kidney stones.