Interesting... I take 2000 iu’s daily in addition to some sun exposure.
I think diabetes has more to do with the daily consumption of animal products and processed foods than lacking Vitamin D.
We take 4,000 units of D3 per day along with K2 to prevent osteoporosis but I think you are right about the processed food. We stay away from that as well as soda pop and high sugar desserts. Type 11 diabetes is usually overweight and diet. My BIL would likely not have half his health problems if he would just shed 60 lbs and walk around the block and give up the choritzo sausage every morning.