In terms of their genetic architecture monogenic diabetes and type 2 diabetes represent two extremes. Whereas each subtype of monogenic diabetes is caused by one penetrant, rare mutation in a single gene, the genetic susceptibility to type 2 diabetes can be attributed to many low-penetrant variants across the genome. At present, only 10% of the genetic susceptibility to type 2 diabetes can be explained by the hitherto identified 90 genomic loci. Here we briefly review the genetics of monogenic diabetes and type 2 diabetes and outline future directions of research within this field.