Background: A recent study reported that some patients with diabetes who fast overnight for laboratory tests are at risk of developing hypoglycemia, which could occur while patients are in risky situations which could result in harm to patients or others. Due to limitation in study design of the aforementioned study, the causes of hypoglycemia could not be elucidated. Objective: To better understand fasting-evoked en route hypoglycemia in diabetes (FEEHD), a recently recognized overlooked safety problem in diabetes management. Methods and Patients: A recent study reported that some patients with diabetes who fast overnight for laboratory tests are at risk of developing hypoglycemia, which could occur while patients are in risky situations which could result in harm to patients or others. Due to limitation in study design of the aforementioned study, the causes of hypoglycemia could not be elucidated. We undertook this retrospective case series study, which enrolled 4 consecutive cases of fasting hypoglycemia in patients with diabetes who were on diverse antidiabetic medications. The study duration was June 1, 2010 to June 1, 2012. Results: The 4 cases (3 women, 1 man), with either type 1 or type 2 diabetes, revealed multiple defects in either the patients’ knowledge and education regarding preparation for lab tests requiring fasting. The degree of hypoglycemia ranged from mild (65 mg/dl) to severe (31 mg/dl), and the events were either mildly symptomatic or asymptomatic. The possible causes of, and contributing factors to hypoglycemia are discussed, and recommendations for preventive measures are provided. Conclusion: Some patients with diabetes who fast for lab tests are at risk of hypoglycemia, and there seems to be an overall lack of proper education of patients with diabetes about this form of hypoglycemia. This overlooked problem can be prevented by proper education and preparation.
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