Final answer:
Gene cloning allows the production of human insulin by transforming bacterial cells, providing a consistent insulin source for treatment of type 1 diabetes. This is crucial as there was no method to create insulin externally before this technology, enhancing the availability and control of insulin treatment.
Step-by-step explanation:
The technology that makes it possible for diabetic patients to purchase human insulin from a pharmacist is gene cloning. Previously, there was no known method to produce human insulin outside of the human body. However, with the advent of gene cloning, the human insulin gene was cloned and used to transform bacterial cells. These modified bacterial cells are now capable of producing human insulin in large quantities. This advancement is a significant benefit as it provides a consistent and controlled source of insulin, which is the only treatment for type 1 diabetes. For those with insulin non-responsive diabetes mellitus, this technological development doesn't directly impact their treatment since their diabetes is characterized by a lack of response to insulin due to factors like defective insulin receptors or insulin antagonists.