This is a passionate book written by a man who survived type 1 Diabetes and made it his life's work to do the same. To this end, he retrained as a medial doctor at the age of 45. He knows full well that managing type 1 diabetes is a life or death situation and writes with great sincerity.
The book is full of good science as well as detailed practical information that someone with type 1 diabetes would find very helpful. If you are a type 2 diabetic, pre-diabetic, or simply worried that you might have diabetes, then this book contains a lot that you don't need to know. In this case, I'd suggest you start instead with Patrick Holford's
Say No To Diabetes, which you will find more relevant.
Both books advocate a low carbohydrate diet as the means to normalising blood sugars. It's scandalous that the medical establishment still does not do the same.
Five stars if you are a type 1 diabetic, three stars otherwise.