Among adults aged 65 years, the prevalence of diagnosed diabetes was 15.3%, representing 5.4 million individuals in the U.S. The prevalence of undiagnosed diabetes was 6.9% or 2.4 million individuals. Elderly individuals with middle age– onset diabetes had a much greater burden of microvascular disease but have a similar burden of macrovascular disease compared with individuals with elderly onset diabetes. Elderly individuals with middle age– onset diabetes had substantially worse glycemic control compared with either elderly onset. Individuals with elderly onset diabetes were also less likely to be taking glucose-lowering medications.