Even fat will raise insulin when eaten in conjunction with glucose.

Michael Eades shows some very interesting stuff about insulin response in relation to the structure of foods and combination foods. Foods high in both fat and carbs (sugar) are rare in nature. Yet that is the perfect combination to make us fat. And that is what many of the processed foods are made of, fat and carbohydrates.

https://www.youtube.com/watch?v=qMO-5mq3crU

John