Hyperuricemia and Cardiovascular Risk Factors in Working-Age Population

Part 3: Inverse U-Shape Relationship between Serum Uric Acid and HbA1c Disappears with Medication for Diabetes Mellitus

Abstract

　Background: The relationship between hyperuricemia and diabetes is complex and unclear.

　Subjects and Methods: Mean uric acid levels were compared between each HbA1c category in 4259 people untreated for hyperuricemia. They were then divided into a non-diabetic treatment category (3888 patients; prescription (－) group) and a diabetic treatment category (371 patients; prescription (＋) group). The impact of eGFR was also investigated.

　Results: 1) The mean uric acid level in the prescription (－) group was significantly higher than that in the prescription (＋) group (6.0 ± 1.2 mg/dL vs 5.5 ± 1.2 mg/dL, p＜0.001). 2) In the prescription (－) group, the mean uric acid level increased with a rise in the HbA1c level within the normal range, but declined when the HbA1c exceeded 6.5, exhibiting an inverse U-shape. 3) On the other hand, in the prescription (＋) group, the mean uric acid level in each HbA1c category remained flat, and the above relationship was not observed. 4) The mean uric acid level was significantly higher in the reduced renal function group (eGFR＜60) than in the normal renal function group (eGFR≧60) (6.6 ± 1.2 mg/dL vs 5.9 ± 1.2 mg/dL, p＜0.001). An inverse U-shaped relationship was observed between HbA1c and uric acid levels in the normal renal function group, but no such relation was observed in the reduced renal function group.

　Conclusion: An inverse U-shaped relationship between serum uric acid and HbA1c levels was observed in the non-diabetic treatment group, but was not observed in the diabetic treatment group. In addition, a similar inverse U-shaped relationship was observed in the normal renal function group, but was not observed in the reduced renal function group. These results suggest the need for caution in assessing cardiovascular risk.