My GFR at 89 ml/min, is this reading normal?

GFR of 89. It is nice that you have diabetes and have a GFR that is in chronic kidney disease (ckd) stage 2. A more important fact is do you have proteinuria/day (p)? You had a 24 hour urine for creatinine clearance to get your GFR level. If you did not have your protein (p) checked, you should ask your doctor to repeat a 24 hour urine for p. Patients with high p do much worse than those with a lower p.