No it isn't. The Practice Guidelines from the American Association of Clinical Endocrinologists are summarized in this PowerPoint presentation from their website.[1] It is not intended for lay consumption, but you can clearly see that there is a large emphasis on diet changes and weight loss. However, as I mentioned in another comment, the reality in practice is that many people are either unwilling or unable to change their lifestyle sufficiently to reverse the condition.

Even before being diagnosed with a disease there are huge returns to regularly exercising and staying fit. You feel better, look better, have more energy, sleep better, the list continues. A doctor saying, "you need to lose weight and exercise, it could help with your diabetes," is a relatively small motivator compared with all of the other benefits.

1. https://www.aace.com/files/aace_algorithm_slides.pptx

Actually the first answer to type II is usually metformin, unless you present initially with pretty advanced disease.