The use of insulin injections for treating diabetes applies to
A. Type 1 diabetes only.
B. type 2 diabetes only.
C. all types of diabetes.
D. gestational diabetes.

A. Type 1 diabetes only

Explanation:

It is sometimes used for type 2, but rarely. Type 2 diabetics still produce insulin, just not quite enough, and it doesn't work properly. They need a natural way to increase insulin. Type 1 diabetics produce little to none, and need to have synthesized insulin injected.