Prevalence of autoantibody-negative diabetes is not rare at all ages and increases with older age and obesity.
Wang J, Miao D, Babu S, Yu J, Barker J, Klingensmith G, Rewers M, Eisenbarth GS, Yu L. Prevalence of autoantibody-negative diabetes is not rare at all ages and increases with older age and obesity. J Clin Endocrinol Metab. 2007 Jan; 92(1):88-92.