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The increase in serum creatinine
is a indication of shutting down of the kidney functions so your husband is probably having renal failure
.The reason for the failure can be diabetes
as it is known to cause diabetic nephropathy
which is a degenerative disease of the kidneys.Since he is under treatment of the best available doctors i guess his treatment is going on properly.So you can discuss the issue with your treating doctors and they will be in a better position to advise on the issue.