Diarrhea Causes..Concerned

Dear Doctor....
My husband is Type 2 Diabetic and was diagnosed approx. 8 yrs ago. He is a 54 yr old African American male..and ever since I can remember....usually within an hour of his eating, he has loose stools. Matter of fact I don't ever recall that his stools are completely "formed" but not watery persay, either...Just LOOSE.
They are never accompanied by cramps...bloating...pain...no obvious bleeding, neither bright red OR "Coffee ground".
He is one of the rare diabetics who doesn't gain weight....but is very small framed, 5'6" and 140 and he has maintained that weight ever since we have been married, going on 24 yrs.
My question is...what could be the causes of him never having formed stools...and I know I cannot view this as a diagnosis...but I would like ideas of what to research as to what COULD cause this.
He DOES take Glucophage, Amaryl and Zocor....and I understand the meds may cause diarrhea but I believe his occurances of loose stools began long before him taking meds for Diabetes and cholestrol.
He is very compliant with his meds and his 3 montly CBCs always check out in the acceptable range.
Thank you.

[Anita Ramsetty, MD]

Hi,
I am sorry if I missed your question. I answered it several days ago but then noticed it still in que, so perhaps it did not go through.

I think your husband should be seen by a gastroenterologist for an evaluation if he has not already done so. Metformin can cause this, but in this case not likely if the diarrhea preceded the medication. He may have a malabsorption problem, bacterial overgroth in the gut, intestinal motion problems from diabetes etc. So definitely speak with a GI specialist about the situation. He should also be checked for possible vitamin deficiencies and anemia given that he may be malabsorbing many nutrients.
Take care and again I am sorry about the late response.