In April 2016, I Had An EGFR Of 87. Although

In April 2016, I had an eGFR of 87. Although I am not diagnosed with diabetes, I think that I have at the very least prediabetes. My doctors' assistants (d.a.) say I do not have it which, based on my April 2016 thorough testing of blood, heart, etc. Yesterday, I paid to have another eGFR test to see what was happening now. The result was 93.3. I was told I did not have kidney disease and probably had a better eGFR rating than the d.a.. However over the past few weeks, I have not urinated nearly the amount of water I've been drinking. I'm drinking it to keep hydrated and also to see what the in-and-out ratio is. I found that it took much more time beforeIfelttheneed to urinate, with much less urine out than what had beenk put in. What is the test(s) I can take to make sure I'm in trouble with that 93.3 result?