Hypoglycemia is the clinical syndrome that results from low blood sugar. The symptoms of hypoglycemia can vary from person to person, as can the severity. Classically, hypoglycemia is diagnosed by a low blood sugar with symptoms that resolve when the sugar level returns to the normal range.
While patients who do not have any metabolic problems can complain of symptoms suggestive of low blood sugar, true hypoglycemia usually occurs in patients being treated for diabetes (type 1 and type 2). Patients with pre-diabetes who have insulin resistance can also have low blood sugars on occasion if their high circulating insulin levels are further challenged by a prolonged period of fasting. There are other rare causes for hypoglycemia, such as insulin producing tumors (insulinomas) and certain medications. These uncommon causes of hypoglycemia will not be discussed in this article, which will primarily focus on the hypoglycemia occurring with diabetes mellitus and its treatment.
Despite our advances in the treatment of diabetes, hypoglycemic episodes are often the limiting factor in achieving optimal blood sugar control. In large scale studies looking at tight control in both type 1 and type 2 diabetes, low blood sugars occurred more often in the patients who were managed most intensively. This is important for patients and physicians to recognize, especially as the goal for treating patients with diabetes become tighter blood sugar control.