The interplay between insulin sensitivity and insulin resistance plays a key role in the development and persistence of type 2 diabetes mellitus. While there are still questions about an universally accepted definition for insulin resistance, it is commonly described as a condition in which cells do not respond adequately to insulin. However, new insights indicate that a more scientific interplay exists between insulin sensitivity and membrane flexibility, which plays a key role in the development and persistence of the type 2 diabetic state. Results from this study highlights the significance of membrane flexibility and raise concerns about the dangers associated with the term ‘insulin resistance’. Aerobic exercise training based on the level of the unsaturation index, a measure of unsaturation that is defined as the mean number of cis double bonds per 100 fatty acid, represents a great step forward in the development of precision medicine in view of type 2 diabetes mellitus