November 6, 2008
Hypoglycemia, Other
Question from Dallas, Texas, USA:
I normally don’t have very low or high blood sugars. I am well controlled and my last A1c was 5.5, with my range being 5 to 6.5, mostly in the mid 5s. I take oral Glucophage and a tiny bit of insulin, four units of NPH and four units of Humalog in the evening with dinner. Every now and then, I do get nighttime hypoglycemia. I did last night and then a couple of weeks ago, usually not that frequent. Anyway, the last two times I woke up with the normal sweating, etc., but, with my eyes closed, I saw a bright green halo which persisted until I got up. After I ate glucose tablets, all the symptoms went away. Two days ago, I saw my eye doctor and we did the normal eye mapping. I have a three year baseline and no changes, plus a peripheral vision test; nothing there was abnormal. So, I wonder what is going on. I know this is a strange question, but it’s really bugging me.
Answer:
I have never encountered this particular symptom when hypoglycemic, nor have I ever heard it from any of my several thousand patients with diabetes. I suspect your are experiencing what is known as a “phosphene,” the artifactual perception of light (colored or otherwise), resulting from insufficient glucose supply to your retina and/or optic nerve. Other than being annoying, it is almost certainly of no real significance.
PC
