Overactive bladder vs. diabetes

Dear Dr. Roach: How can a patient differentiate frequent urination caused by an overactive bladder from an underlying medical problem like diabetes? — A.L. Answer: Both overactive bladder and diabetes (both diabetes insipidus, which is an inability to properly concentrate urine, and uncontrolled diabetes mellitus, which causes loss of water along with sugar) cause excess urination. However, in overactive bladder, the urination may be frequent or urgent, but usually is in relatively small volumes, whereas in diabetes, the urination is frequent and in large amounts. The diagnosis can be suspected by this history; however, it's wise for the physician to obtain blood testing for diabetes insipidus (blood sodium level and sometimes urine concentration) and diabetes mellitus (blood and urine sugar or blood A1c level) in someone suspected of overactive bladder symptoms. It's also appropriate to look for infection, which can cause similar symptoms. In men, considering prostate enlargement is important. Email ToYourGoodHealth@med.cornell.edu.