Fasting for lab tests raises hypoglycemia risk in diabetes
Requiring fasting prior to lab tests may endanger some patients with diabetes by placing them at risk for hypoglycemia, new research indicates.

Findings from surveys of over 350 patients were recently published in the International Journal of Endocrinology by Saleh Aldasouqi, MD, of Michigan State University, East Lansing, and colleagues.

"Patients continue taking their diabetes medication but don't eat anything, resulting in low blood sugar levels that cause them to have a hypoglycemic event while driving to or from the lab, putting themselves and others at risk," Dr. Aldasouqi added. The practice can even have deadly consequences, the authors note, pointing to a case report from Thailand of a sulfonylurea-treated patient with diabetes who had a sudden cardiac arrest in the waiting room of a laboratory. Her blood glucose level was 0 mg/dL.

The study included 363 diabetes clinic patients who fully completed a 2-page survey (out of 572 invited). They were a mean age of 60.6 years and had a diabetes duration of 16 years, and 82% reported having type 2 diabetes. All were taking oral and/or injectable medications for their diabetes and all had had at least one fasting lab test in the prior year.

Just over a third (36%) reported having received education about how to reduce the risk of hypoglycemia, such as reducing their medication doses, or to prevent hypoglycemia-associated danger, such as having another person drive them to the lab. A total of 62 patients (17%) reported experiencing at least one fasting-evoked en route hypoglycemia in diabetes (FEEHD) episode in the prior 12 months, and of those, 11% reported having more than one such experience.

Of the 62 reporting FEEHD episodes, only 33 (53%) recalled mentioning the event to their provider and only 22 (35%) recalled having received some type of FEEHD prevention instructions.

Of the total 363 patients, 36 were taking sulfonylureas or meglitinide analogs, 215 were taking insulin, and 18 were taking both. Thus, 269 (74%) of all patients were at risk for hypoglycemia. Of those 269 patients, 59 (22%) had one or more FEEHD episodes during the prior 12 months.

The study does prove that there is a high rate of occurrence of iatrogenic fasting hypoglycemia resulting from laboratory tests in patients on medications which can induce hypoglycemia (FEEHD). The study has confirmed findings of prior studies that FEEHD occurs in clinical practice and at an alarming prevalence rate. Ordering fasting lipid profiles will not only put patients with diabetes at risk of hypoglycemia, but with the changing guidelines in lipid testing, fasting for lipid tests may not be necessary after all. It is imperative that health organizations, especially diabetes organizations, become more aware of this issue and include specific educational guidelines to prevent FEEHD. As the utility of fasting lipid panel has been deemed doubtful and does not appear to be inferior to nonfasting measurements, it may now be high time to amend lipid management guidelines.

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