My daughter is 13 and has had Type1 diabetes since she was 4. About 6 months ago, she started having severe insulin reactions for three to four days on a monthly basis. We cut her insulin to about one-third of what she had been on. When we discussed this with her pediatric endocrinologists, they tested her for Addison’s disease, but the test was negative. After three or four days of lows, her insulin needs go back to normal. This all started at the same time she started her periods. I have kept records of these lows and they are happening in the middle of her cycle. One month,she did not have these low spells, and she also never menustrated that month. These low times are really scary (with ambulance calls and glucagon kits). What is causing this — should we have her tested for other medical conditions?

In a 13 year old, the most likely cause of unexplained low blood sugars is taking extra insulin. If the lows are associated with her menstrual cycle, it is possible that her blood sugars increase with her periods, and that she takes extra insulin to get the blood sugars down and overdoes it. I’ve seen blood sugars increase with the menstrual cycle, but rarely decrease and not to a degree requiring glucagon.

It is also my impression that some patients will have episodes of unexplained low blood sugars without extra insulin, sometimes following periods of high blood sugars, often treated (appropriately) with extra insulin. One theory is that some patients will intermittently bind insulin to antibodies (making it inactive leading to high blood sugars), then “release” it giving effectively more active insulin in the blood leading to low blood sugars. This is almost impossible to prove, unfortunately. I cannot think of a reason, however, why such an occurrence would be tied to the menstrual cycle.

TGL