It works for David Mendosa, who’s been doing it for three years. He shares some ideas on how to do it at the link below. From the intro:
About nine years ago, I started to eat only food low in carbohydrates that don’t have a high glycemic index. I knew that this was the only proven way to bring my blood glucose level down where I wanted it to be without using drugs or supplements. My most recent A1C test showed that my level is 5.1 percent, well within the range considered normal.
While continuing to eat this way, about three years ago I added the further restriction of eating no meat, fish, or seafood. This was a substantial shift in what I was eating, and I made it mainly because I don’t want to be intentionally responsible for the death of animals or other sentient beings. Only later did I begin to realize its health benefits.
David seems to adhere to the lacto-ovo strain of vegetarianism, rather than vegan or pesco-vegetarian. In other words, he’ll eat eggs and milk products but not fish. I suspect he eats under 40 grams/day of digestible carbohydrate.
Here are more of David’s ideas on implementation of a very low-carb vegetarian diet.