Syncope and Hypoglycemia

Objective: This review focuses on syncope in diabetic patients who suffer from hypoglycemia. Clinically, transient loss of consciousness during hypoglycemia appears similar to vasovagal syncope. Research Design and Methods: Current understanding of this problem is based on physicians’ personal experiences as well as on published case reports. It is difficult to explain a temporary loss of consciousness as a result of hypoglycemia. Demonstration that hypoglycemia can be transient, with the patient suffering from neuroglycopenia without autonomic symptoms due to delayed counterregulation, might be a first step in confirming that a diabetic patient suffered from a transient loss of consciousness with spontaneous recovery. Results: Hypoglycemic syncope is uncommon, affecting 1.9% of diabetic patients using insulin therapy. It is characterized clinically by brief periods of unconsciousness with slow recovery and without loss of postural muscle tone. The difficulty in correlating loss of consciousness to hypoglycemia arises from mismatching symptoms, that is, there may be mental symptoms such as confusion, loss of memory or consciousness, in the absence of autonomic manifestations such as sweating or blurred vision. There are currently no established glucose values that define the level of hypoglycemia that causes loss of consciousness. Conclusion: Hypoglycemic syncope should be suspected in older diabetic patients with preserved postural tone, usually but not always using insulin therapy, who show a slow recovery from transient loss of consciousness with persisting neurological impairment and low blood glucose levels.