Vitamin D deficiency is often found in poorly-controlled diabetic conditions, but they don’t know which causes which. Low levels of vitamin D also leads to fragile bones. I would recommend to ask your doctor to test your level before taking any supplements, if you haven’t already done so. (Excess vitamin D can lead to toxic levels.)

Hello @luluwa and welcome to Mayo Connect. I see that you asked how Vitamin D helps. Here is an article from Mayo Clinic's website about why Vitamin D is important. Just click on the link to read the article,
https://www.mayoclinic.org/drugs-supplements-vitamin-d/art-20363792
@luluwa, Do you have a low Vitamin D level?