November 14, 2004
Exercise and Sports, Insulin
Question from Los Angeles, California, USA:
My 14 year old son was diagnosed with type 1 in April, 2003. At that time he was 5 feet, 5 inches, and weighed 115 pounds, having lost about 15 pounds in the month before he was diagnosed. Eighteen months later, he is 5 feet, 10 inches and 170 pounds He is using just 17 units of Lantus per day, injected at night, and no insulin with food. This has been going on for about six weeks. Before that, his ratio was about 1 unit per 60 grams of carbohydrates and he rarely used more than 22 to 25 units per day. He consumes about 400 grams of carbohydrate per day. He is a very serious athlete, a fencer, ranked second in the U.S. in his age group, and trains approximately two to three hours per day, five days a week. Do you think he is in a very extended honeymoon period? Does his volume of exercise account for his low insulin dose? Does he still has some pancreatic function? > Perhaps it is relevant to note that, at diagnosis, his blood sugar was above 600 mg/dl [33.3 mmol/L], but he had no ketones.
It is somewhat unusual for so little insulin needed in a teenager, but this much activity certainly reduces insulin requirements and could be the explanation. As long as you are doing pre- and post-prandial blood glucose checks and the values are entirely normal, I wouldn’t usually make any dose changes. It’s likely that, over time, his insulin requirements will increase and/or pancreatic function decrease, so this also shouldn’t be surprising. All should be based upon actual blood glucose readings done frequently coupled with advice from your diabetes team, A1c readings etc. Your diabetes team can do more sophisticated pancreatic reserve testing (i.e. C-peptide levels) but the blood glucose readings indirectly provide similar information.