In Reply: We agree with the general premise of Drs Graveling and Frier that caution is appropriate in observational studies of treatments and their consequences. However, we believe the strength of the relationship we observed between severe hypoglycemic episodes and dementia, its graded nature, and its robustness to the numerous adjustments we reported justifies caution against overtreatment of older patients with diabetes. As pointed out in the article, 3 recent randomized trials of tight glycemic control resulted in large differences between groups in the incidence of severe hypoglycemia. With time, these trials will provide more definitive answers to the question of whether hypoglycemia causes neurologic injury and dementia.
Whitmer RA, Karter AJ, Selby JV. Dementia and Hypoglycemic Episodes in Patients With Type 2 Diabetes Mellitus—Reply. JAMA. 2009;302(8):843-844. doi:10.1001/jama.2009.1206