Question from Indiana, USA:

Let me preface this question by letting you know we have consulted our pediatric endocrinologist and are following the teams’ plan. We are puzzled by our 10 year old son’s sudden increase in insulin sensitivity. No explanation has been tendered as to why it is occurring. We have been advised as to how to treat. He was diagnosed five years ago.

He has been on the following regimen for the past four months: in the morning, one unit of Humalog for every 18 grams of carbohydrates–correction factor: Blood sugar -120/90 mg/dl [6.7/5.0 mmol/L]; 22 units of NPH; in the evening, one unit of Humalog for every 15 grams of carbohydrates–correction factor: Blood sugar -120/60 mg/dl [6.7/3.3 mmol/L]; three and a half units of Lantus. My son has a one carb (15 grams of carbohydrates) about every two hours and a set number of carbohydrates at lunch. Recently, he has been having numerous lows at 4:30 p.m. and 7 a.m.

This week, using the same regimen outline above, his blood sugars have bottomed out. He went to the Emergency Room last night after his blood sugar went below 20 mg/dl [1.1 mmol/L] and he encountered convulsions. We treated him with food, cake frosting, glucose, etc. He did not respond. After being at the hospital for several hours with a 5% dextrose solution, his blood sugar was in the 80s mg/dl [4.4 to 4.9 mmol/L]. When we got home and checked his blood sugar, it was again falling. Before bed, he ate a ham sandwich, a turkey sandwich, a cup of chocolate milk, two pieces of cinnamon toast, and half a milk shake. His blood sugar was 200 mg/dl [11.1 mmol/L] when we went to bed. We checked his blood sugar hourly through the night and it climbed steadily. This morning, his blood sugar was in the 400s mg/dl [22.2 to 27 mmol/L]. We gave him his breakfast and the usual carbohydrate ratio of Humalog, plus Humalog for a correction. He received his usual 22 units of NPH. His blood sugar has been low ever since. He has had to ingest large amounts of food and sweetened beverages to keep his blood sugar between 60 and 170 mg/dl [3.3 and 9.4 mmol/L]. We are watching it closely and are trying to keep it a little high to prevent another drop out.

Why would a regimen he has been on for several months, without ill effect, suddenly cause my son to bottom out and have difficultly bringing up his blood sugar? Activity, diet and dosages have remained fairly constant. Could it have something to do with a growth spurt? Could it be pre-puberty related? What could cause an increase in sensitivity?