Seizures in the setting of hypoglycemia are well described. The brain needs sugar to function and when the blood sugar falls “too low”, one of the things that can happen is that the patient may have a seizure (this is usually a generalized convulsion-a tonic-clonic or Grand Mal seizure). There is no one level of blood sugar below which one has a seizure (rather the level varies from person to person). Let me explain that with an example. Lets assume you are a diabetic and you take your insulin shot but for once forget to take a meal (maybe you are a hard working executive on the run). You have a convulsion while at work and are taken to the nearest ER. There your blood sugar at the time of presentation is recorded to be 60 mg/dl. There might be another similar patient whose blood sugar falls to 52mg/dl yet he does not have a convulsion. So there is no set limit below which the brain shall have a seizure but speaking in broader terms usually the brain does not tolerate blood sugar below 60mg/dl and below 40 mg/dl most patients shall be symptomatic (either have a convulsion or be confused and obtunded. The term used for this constellation of neurological signs and symptoms as a result of hypoglycemia is NEUROHYPOGLYCEMIA).
The good news though is that seizures due to hypoglycemia are readily treatable. In the ER we load the patient with glucose (usually this is given via an intravenous drip as the patient is obtunded and confused and cannot accept anything from the mouth). The blood sugar quickly rises and the seizures stop. Patients who suffer from hypoglycemic seizures do not need to be on an anti-epileptic drug. These patients do not have epilepsy. If their blood sugar does not fall down again, they will not have another seizure.
Rather a meticulous search should be conducted to find out the cause of hypoglycemia:
-is the patient a diabetic who took too much insulin by mistake?
-did he miss his meal but took his insulin?
-is there any other cause of hypoglycemia such an insulin secreting tumor?
-is the patient septic?
Hypoglycemic seizures are most commonly seen in diabetics. This emphasizes the importance of good glycemic control in this vulnerable population.
Nitin Sethi, MD