Hypoglycemia
Medical Author: Ruchi Mathur, MD
Medical Editor: William C. Shiel Jr, MD, FACP, FACR
and Melissa Conrad Stöppler, MD
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Hypoglycemia & Diabetes: How Low Can You Go?
Medical Author: Ruchi Mathur, M.D.
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR
 I am fortunate to have a team of great nurses and a wonderful nutritionist in my office. As I was
on my way into see a patient, I overheard one of our nurses
going into a great deal of detail educating a young patient with diabetes about
the concerns of low blood sugar. Her talk reminded me that this is a subject of great importance to
patients with diabetes. I will take this opportunity to highlight information on
issues related to hypoglycemia. Namely, what are the signs and symptoms of
hypoglycemia, when should you be concerned, what to do for treatment, and when
you should seek medical attention.
Despite significant advances in diabetes treatment,
hypoglycemia (low blood sugar or glucose) is still a common problem among
patients who are trying to achieve better control of their blood sugar.
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What is hypoglycemia?
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.
Who is at risk for hypoglycemia?
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.
I thought high blood sugar was bad. Why is low blood sugar also bad?
The
body needs fuel to work. One of its major fuel sources is sugars, which the body
gets from what is consumed as either simple sugar or complex carbohydrates. For
emergency situations (like prolonged fasting), the body stores a stash of sugar
in the liver as glycogen. If this store is needed, the body goes through a
biochemical process called gluco-neo-genesis (meaning to "make new sugar") and
converts these stores of glycogen to sugar. This backup process emphasizes that
the fuel source of sugar is important (important enough for human beings to have
developed an evolutionary system of storage to avoid a sugar drought).
Of all the organs in the body, the brain depends on sugar (which we are now
going to refer to as glucose) almost exclusively. Rarely, if absolutely
necessary, the brain will use ketones as a fuel source, but this is not
preferred. The brain cannot make its own glucose and is 100% dependent on the
rest of the body for its supply. If for some reason, the glucose level in the
blood falls (or if the brain's requirements increase and demands are not met)
there can be effects on the function of the brain.
Next: Can the body protect itself from hypoglycemia? »
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