My 9 1/2 year old type 1 diabetic daughter has had diabetes for 4 years now. Her blood glucose level has gone as low as 19 and she has never gone unconscious. I feel lucky in a sense, but why hasn’t she? How low can one go before unconsciousness occurs? I know everyone varies but still 19 is way, way too low.

There are a number of reasons why your daughter’s blood sugar might have appeared to be below 20mg/dl without causing any neurological signs and the first of course is that the glucose meter you use might have be incorrectly calibrated or that your technique might be at fault. Certainly it would be worth checking these points with the nurse educator in your diabetes team. Nevertheless the variable responses to low blood sugars between individuals has long been both recognised and poorly understood. The usual explanation has been that although glucose is by far the most important metabolic fuel in the brain that in emergencies other substances like lactate, pyruvate, acetate and some amino acids can assume some of that role. Again the capacity to do this seems to be variable. In addition, intracerebral circulation [blood flow within the brain] can adjust to protect the cerebral cortex [the portion of the brain responsible for consciousness]. As always, if you are concerned about hypoglycemia, the key is ‘prevention’ — that is to say, developing a profile of blood sugars throughout the 24 hours and then appropriately adjusting insulin, diet and exercise to match.

DOB