Diabetes Risk and Blood Glucose

Patient Expert

Is a blood glucose (BG) level above 100 mg/dL in someone who doesn't have diabetes something to worry about?

Most of us would say no. Many nondiabetics go up to about 120 mg/dL, sometimes even a little higher, after meals. But then they come back to the starting level within a couple of hours.

And a new study suggests that any random BG reading over 100 is a risk factor for prediabetes and diabetes (see Table 2 in that paper).

But that's not as important than body mass index (BMI), right. Wrong In fact, such a reading is about three times more predictive than BMI, which most people, and especially the popular press, consider to cause diabetes.

So what does this mean for us? Many of us have tested the BG levels of relatives but haven't really known what to do with the results. The traditional definition is that a random BG measurement up to 200 mg/dL is considered nondiabetic. Does this study mean that any BG measurement over 100 is abnormal?

I don't think so. The point here is that the random BG level is just that, random. Some of those measurements will be before meals, some of them will be fasting, some of them will be an hour after a meal, and some of them will be 2 or more hours after meals. Nondiabetics usually return to the starting level within a couple of hours. It's only at the 1-hour point that nondiabetics tend to peak, if that.

So if you test a bunch of nondiabetics, unless you make a point of testing at the 1-hour point, most of them will have BG levels under 100 mg/dL. This article has links to graphs showing the BG levels of nondiabetics both as averages and as individuals. When you look at the individual results, you can see that some people go up to 160 after meals (but   come down quickly) and others stay below 100 the whole time.

If this new study is confirmed, it will greatly simplify the early diagnosis of people who don't have good medical care. One simple BG test would suggest whether or not the person needed more extensive evaluation.

And early diagnosis is the best way to ensure that people are treated before their beta cells are completely burned out.

More useful articles on diabetes diagnosis:

Understanding Prediabetes

Diabetes and Longevity

Genes and Diabetes