In the coming decades, the population of older adults with type 2 diabetes mellitus is expected to grow substantially. Understanding the clinical course of diabetes in this population is critical for establishing evidence-based clinical practice recommendations, identifying research priorities, allocating resources, and setting health care policies. OBJECTIVE To contrast the rates of diabetes complications and mortality across age and diabetes duration categories. This cohort study (2004-2010) included 72,310 older (? 60 years) patients with type 2 diabetes enrolled in a large, integrated health care delivery system. Incidence densities (events per 1000 person-years) were calculated for each age category (60-69, 70-79, and ? 80 years) and duration of diabetes (shorter [0-9 years] vs longer [? 10 years]). Incident acute hyperglycemic events, acute hypoglycemic events (hypoglycemia), microvascular complications (end-stage renal disease, peripheral vascular disease, lower limb amputation, and diabetic eye disease), cardiovascular complications (coronary artery disease, cerebrovascular disease, and congestive heart failure), and all-cause mortality. Among older adults with diabetes of short duration, cardiovascular complications followed by hypoglycemia were the most common nonfatal complications. For example, among individuals aged 70 to 79 years with a short duration of diabetes, coronary artery disease and hypoglycemia rates were higher (11.47 per 1000 person-years and 5.03 per 1000 person-years, respectively) compared with end-stage renal disease (2.60 per 1000 person-years), lower limb amputation (1.28 per 1000 person-years), and acute hyperglycemic events (0.82 per 1000 person-years). We observed a similar pattern among patients in the same age group with a long duration of diabetes, with some of the highest incidence rates in coronary artery disease and hypoglycemia (18.98 per 1000 person-years and 15.88 per 1000 person-years, respectively) compared with end-stage renal disease (7.64 per 1000 person-years), lower limb amputation (4.26 per 1000 person-years), and acute hyperglycemic events (1.76 per 1000 person-years). For a given age group, the rates of each outcome, particularly hypoglycemia and microvascular complications, increased dramatically with longer duration of the disease. However, for a given duration of diabetes, rates of hypoglycemia, cardiovascular complications, and mortality increased steeply with advancing age, and rates of microvascular complications remained stable or declined. Duration of diabetes and advancing age independently predict diabetes morbidity and mortality rates. As long-term survivorship with diabetes increases and as the population ages, more research and public health efforts to reduce hypoglycemia will be needed to complement ongoing efforts to reduce cardiovascular and microvascular complications.