To the Editor.
—We read with interest the study by Dr Shorr and colleagues, which suggests that antihypertensive drug therapy has little impact on the risk of hypoglycemia in older diabetic patients. Three reasons may have led to these results. First, the authors express concern about the possibility of "confounding by contraindication" in relation to β-blocker use, which may have resulted in an underestimate of the risk. The concern is appropriate, since β-blockers have a well-recognized hypoglycemia-masking effect, and caution is usually recommended regarding their use in diabetic patients. A history of hypoglycemic episodes may reduce the likelihood that a patient will be prescribed β-blockers and is a risk factor for future episodes of hypoglycemia. In the Diabetes Control and Complications Trial (DCCT), the number of prior episodes of hypoglycemia was the strongest predictor of the risk of future hypoglycemic episodes in insulin-treated diabetic patients.2 It would have been interesting to measure