Thank you very much for your reply.
GFR is the flow rate of filtered fluid through kidneys and overall a good measure of kidney function.
Well according to GFR of 40 reading.....it means decline in your kidney function of moderate severity..which is clinically taken as Chronic Kidney Disease Stage III. It is fairly common among Diabetic patients to have silent decline in kidney function so regular kidney function evaluation with protein check in urine and creatinine is recommended.
Now what i can suggest is that your Diabetic control seems quite reasonable from readings but to be more precise i would suggest to check your HbA1C levels and keep around 6.5%. This is ideal level recommended to avoid complications.
Second your blood pressure should be below 125/75 and titrate your medication to achieve this target. Lisinopril is excellent in protecting kidney from Diabetic effects and continue it but dose should be adjusted to achieve this recommended level.
Rest your routine sounds OK. Above mentioned suggestions will not reverse kidney damage already done but FOR SURE will slow down further deterioration in kidney function.
Last thing that even at this level of GFR you can have contrast tests of heart with low osmolar or iso-osmolar dyes and using minimum possible dye dose like 20-30 ml in which test can be performed. Pre-procedure preparation with good hydration and N-Acetylcystein and soda bicarb will further have protective effect against contrast.This is something which you can discuss with your doctor in case that dye test is absolutely essential.
This conversation is open till you feel satisfied. Let me know if you have any further query. I will be glad to answer those