INS and acanthosis nigricans: We recommend genetic testing for patients suspected to have MODY or when etiology of DM is unclear; suggestive features include young onset, absence of beta cell autoantibodies, low insulin requirement, persistent measurable C-peptide levels, isolated renal glycosuria with or without renal abnormalities, and persistent hyperglycemia without ketoacidosis in patients with T1DM; or hyperglycemia without obesity, acanthosis nigricans, insulin resistance, and normal triglyceride and low-density lipoprotein in patients with T2DM [5].