Here is some evidence of the intrinsic variability of glucose levels from my daily logbook. I always eat the exact same amount of the exact same food every day, so the calories consumed and their glycemic index are constant. I live in such a routine way that I always expend the same amount of calories per day, so activity is constant. And also, over the last six days, I have taken exactly the same amount of insulin, including Lantus and Humalog, each day at breakfast. But despite holding constant every measurable and controllable influence on blood sugar levels, they still fluctuate spontaneously in a way that frustrates all efforts at control.
So here are the blood sugar results of the first half of the last six days. I should add that I have always found such spontaneous variability typical.
Morning Blood Sugar: 50 Noontime Blood Sugar: 79
Morning Blood Sugar: 54 Noontime Blood Sugar: 103
Morning Blood Sugar: 34 Noontime Blood Sugar: 83
Morning Blood Sugar: 54 Noontime Blood Sugar: 58
Morning Blood Sugar: 49 Noontime Blood Sugar: 49
Morning Blood Sugar: 49 Noontime Blood Sugar: 148
The effect of exactly the same dose of food, insulin, and activity on the morning blood sugar seems essentially random. Two morning 54s produce afternoon values of 103 and 58, while two morning 49s produce afternoon values of 49 and 148. And yet so many doctors assume that all blood sugar variations must be because the patient did something naughty so he/she should be scolded, and even one textbook on diabetes I read introduced the chapter on complications by saying, “For diabetics who choose not to control their blood sugar, complications may develop.”