Hypoglycemia Can Induce Visual Disturbances in Diabetes


SAN FRANCISCO — Visual disturbances—including blurred vision, floaters, central scotoma, and even complete loss of vision—can be a symptom of hypoglycemia in some patients with diabetes, according to Dr. Mukhtar Khan.

Although not all those with diabetes experience visual disturbances during a hypoglycemic event, those who are susceptible might experience two or more, which resolve soon after blood glucose stabilizes, Dr. Khan wrote in a poster presented at the annual meeting of the Endocrine Society.

“Most clinicians are usually concerned about hyperglycemia and its effects,” he said in an interview. “It is also important to keep the effects of hypoglycemia in mind, especially the visual effects, as these can have devastating consequences in diabetic patients in situations such as operating a motor vehicle.”

His observational study enrolled 40 patients with diabetes (mean age 46 years) who had a history of visual symptoms during hypoglycemic episodes. Most of the patients (26) had type 1 diabetes; the rest had type 2 diabetes. Nineteen were on insulin pumps, while 21 were on various insulin regimens, including glargine, lispro, aspart, and mixed regimens.

For most of the patients (57%), visual symptoms occurred when blood glucose dropped to 30–50 mg/dL. For 25%, symptoms occurred at a glucose level of 51–65 mg/dL, while a minority (10%) experienced them at a level of 66–80 mg/dL. The remaining patients were unable to document their blood glucose level at the onset of visual symptoms.

Blurred vision was the most commonly reported symptom (77%). About half of the group (47%) reported seeing floaters. Dimming of vision occurred in 37%; central scotoma (a black spot or “hole” in the central visual field) in 32%; and double vision in 22%. A few patients (5%) reported a complete loss of vision during hypoglycemia. Most (67%) reported more than one symptom during the episode.

The visual disturbances resolved after blood glucose stabilized, Dr. Khan said. “After hypoglycemia correction, the symptoms resolved within 5–15 minutes in 16 subjects; 20–30 minutes in 17 subjects; and 35–90 minutes in three subjects. Two subjects, who experienced a complete loss of vision at a blood glucose level in the 30- to 40-mg/dL range, reported gradual resolution of visual symptoms in 180 minutes and 300 minutes after improvement in the glucose level.”

Two patients did not report the time to resolution of their symptoms, noted Dr. Khan of the State University of New York, Syracuse.

“Patients with diabetes should be counseled about recognition and early management of visual effects of hypoglycemia,” Dr. Khan said. “Prevention of hypoglycemia should be given as much importance as hyperglycemia during management of diabetes.”

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