There are millions of Americans who require insulin for the medical treatment of diabetes.  Doctors who direct the therapy of these patients often recommend what is referred to as 'tight' glucose control.  Such a regimen necessitates multiple injections of insulin throughout the day designed to keep blood sugar levels within normal limits at all times.  The purpose of this approach is to minimize the chances of developing cardiovascular complications (such as heart attack and stroke) that are associated with poor blood sugar regulation.  This requires frequent blood sugar testing throughout the day, calculation of insulin doses based upon the blood sugar level, and frequent injections of insulin.  One of the most troubling complications of this type of therapy is hypoglycemia (low blood sugar).  These hypoglycemic episodes are directly related to the injection of an excess of insulin.  When this occurs, symptoms may develop that include tremulousness, jittery feelings, dysphoria, and slowed mentation.  In the presence of even lower glucose levels confusion, somnolence and coma may ensue.  These constitute medical emergencies.  Whether these episodes are mild, or more severe, they are not good for the health of the brain.  Yet, for diabetics they are an unfortunate fact of life.  They may develop slowly, or more rapidly.  With a gradual onset the patients are trained to eat or drink something containing a rapidly digestible source of glucose to counteract the falling sugar level.  This frequently is sufficient to mitigate symptoms of hypoglycemia, but may generate an associated surge, or overshoot, of blood sugar-an undesirable result.  Such is the life of a person grappling with diabetes.  

Anything that would alleviate the occasionally serious signs and symptoms arising from these episodes would be helpful for a large segment of the population and would save many neurons.  A clever study, published in the medical journal Diabetes (1994;43:1311-1317), provided clues to this dilemma.  The brain usually depends almost exclusively on glucose to supply its substantial energy requirements.  During hypoglycemia associated with prolonged fasting or strenuous exercise, circulating ketone body levels increase many-fold.  Ketone bodies (acetoacetate and beta hydroxybutyrate) are products of partial fat metabolism which are generated in the liver and are secreted into the circulation.  They constitute a fuel source that is easily burned by the brain and is able to provide the energy the falling blood glucose can't.  This study was designed to investigate whether ketones would provide similar protection under insulin-induced hypoglycemia.  The experimental conditions were chosen to model what happens when diabetics become hypoglycemic due to injection of too much insulin.

Infusion of precise amounts of insulin was performed in two groups of subjects, one who had shortly before received an infusion of ketone bodies, and one group who had received a placebo (inactive infusion containing no ketone bodies).  Blood samples were then drawn and cognitive function testing was performed. 

Compared to the group that received insulin plus placebo (no ketones), the group that had insulin plus ketone bodies had reduced signs and symptoms of hypoglycemia.  They remained asymptomatic until blood glucose levels fell to the 40 mg/dl range compared to the production of symptoms in the more typical 50 mg/dl range of blood sugar in the other group.  These remarkable findings suggest that ketones help protect neurons from severe hypoglycemia.  While such therapy may not be useful in all circumstances, it is expected to expand the safety margin of tight glucose control in a large number of diabetic patients. 

Ketone body therapy is not currently available.  However,  when taken as a supplement to the diet MCT oil (medium chain triglyceride) is rapidly turned into ketone bodies which would be expected to produce the same beneficial effect.