How do you approach hematuria in a patient with diabetic nephropathy?

This is a difficult question to answer. If young, no risk factors for GU malignancy and only microscopic hematuria would generally not pursue but make patient aware of small risk and make sure PCP also knows. Helpful to know if red cells are dysmorphic and if there is also proteinuria. Gross hematuria needs GU evaluation. If older or with GU malignancy risk factors safest to have GU evaluation. Safest for patient perhaps but definitely for the doctor's malpractice insurance company!

If it is mild and inconsistent I likely won't do anything about it. If consistently there, then I would strongly consider doing kidney biopsy after doing preliminary serological testing. It is also all dependent on patient's wishes but in general I think it is good idea. Most often coexisting kidney disease is IgA nephropathy, I don't remember last time I saw another disease in combination with diabetic nephropathy.

Microaneurysmal rupture can be seen which may lead to hematuria.