<h4>Context</h4>The proinsulin to C-peptide (PICP) ratio reflects beta-cell stress and has been shown to decrease following diet-induced weight loss.<h4>Objective</h4>To compare the changes in PICP following a ketogenic (KD) or a low-fat diet (LFD) in individuals with type 2 diabetes (T2D).<h4>Methods</h4>The sample was 55 (±7) years of age, majority female (76%), and 54% African American. This evidence concerns the gene INS and type 2 diabetes mellitus.