I’ve always thought it was the texture. But it worked ok in the smoothie. DIL said to freeze the yogurt overnight and omit the icecream. Pretty smart of her. My first smoothie was way too sugary. My CGM wasn’t happy with my choices and let me know.
So no more icecream for breakfast, dang it!
Wish I had something to offer other than sympathy and well wishes. Dated a diabetic for about 4 years between weddings. In that time I watched her go from controlling it with diet and exercise along with cholesterol meds to insulin dependence and kidney problems.