Diabetes mellitus is very common in older persons. Changes in exercise habits, body habitus, leptin, amylin, tumor necrosis factor alpha, and nitric oxide all play a role in the pathogenesis of age-related insulin resistance. In older persons elevated glucose levels not only produce retinopathy, neuropathy, and nephropathy but also decrease quality of life, pain tolerance, cognition, and functional status and increase injurious falls, nocturia, incontinence, pressure ulcers, and orthostatic hypotension. The availability of multiple new therapies has enhanced the ability of physicians to improve glycemic control in older persons without unacceptable levels of hypoglycemia. Caregivers play an important role in the management of older diabetics. Depression increases mortality rate and hospital admissions in older diabetics. In many nursing homes the quality of diabetic care is marginal. A new causative theory of the metabolic syndrome involving cytokines and nitric oxide-the NO cytokine theory-is proposed.