First of all, your diabetes must be under control.
Also, you need to see if there is a problem with the bladder: you need to have a diagnosis...diabetes is a common cause, kidney disease [this MUST be ruled out by your doctor], and bladder disease.
All of these must be excluded.
As to your question, there is no such thing as a homeopathic medicine for stopping frequent urine. There are many different homeopathic remedies, and they are chosen based on careful analysis of your entire history, exam and symptoms.
There are 290 different remedies that have been shown useful in frequent urination.
You will need to find a classical homeopath, well trained, to examine you, talk with you extensively, and narrow this down to the best remedy.
I can tell you the top possible remedies, but I need some questions answers:
a. is your diabetes under control
b. what other symptoms with the frequent urination to you have
Is there a time of day when this is worse
Is there anything that makes it worse
Is there anything that makes it better?