You don't give your son's age, if he is an adult, magnesium is a noninvasive approach that I wrote about previously here :
I wrote about it for type 2 diabetes (T2DM), but it would be beneficial for type 1 also.
I also wrote about the use of Berberine for T2DM, but it can also be helpful for type 1 as it is known to lower blood sugar level and insulin resistance while improving insulin sensitivity :
Another useful supplement for diabetes is Benfotiamine, a fat soluble form of vitamin B1. There are other supplements that can offer benefit such as vitamin D. These four supplements have studies to support their use for diabetes and other health issues and have good safety profiles in human studies.
Because of the seriousness of diabetes and the fact that these supplements can reduce glucose levels, and increase insulin sensitivity, increasing the potential for hypoglycemia(low blood sugar), which can be very dangerous, it is imperative that you and or your son use these supplements under the supervision of a doctor or medical healthcare professional.