Brief Answer:
Post Micturition Shudder Due to Autonomic Neuropathy

Detailed Answer:
Dear Madam,

Welcome to HealthCareMagic.com I am Dr.Bruno Mascarenhas, and I will be answering your queries. I have read your question with care and understand your concerns. Let me try to help you.

Let us See some basics

I
You have diabetes. So you are likely to have Neuropathy

II
There are three muscles related to Micturition (1) Detrusor - which is relaxed during most times and which contract when we pass urine (2) Internal Sphincture - which is contracted during most times and relax when we pass urine. (3) External Sphincter which is contracted during most times and relax when we pass urine.

Of these, (1) Detrusor and (2) Internal Sphincter are controlled by Autonomic Nervous System while (3) External Sphincter is controlled by Voluntary Muscles

So
Essentially, Urination (called Micturition) is mediated by the Autonomic Nervous System

III
Two things happen when a person passes urine
(1) His/Her Private Parts, which were so far warm inside at least two layers of dress are suddenly exposed to cold
(2) Warm Urine is being send out
So
Essentially brain gets a signal that it is cold outside

(IV)
So, brain send orders to restore body temperature. (You may know that One of the defense mechanism of the body during cold climates is shivering and rattling of teeth) This happens via Autonomic Nervous System.

At the same time, Autonomic Nervous System is already doing its job of emptying the bladder

These two signals clash and hence there is a shudder in most people. But, soon the brain will realize that all other parts are warm and the private parts are also now warm and there is no need to shiver

(V)
In your case, because of your diabetes, there is Autonomic Neuropathy
So
The signals are misdirected and your signals are sent to your hand to make them warm. Hence there is increased blood flow in your hands and this makes your hands warm

Hope you found the answer helpful.

If you need any clarification / have doubts / have additional questions / have follow up questions, then please do not hesitate in asking again. I will be happy to answer your questions.

Best Wishes for Speedy Recovery
Let me know if I can assist you further.
Take care.

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