Defining Diabetes Downward -- Or, What's Normal Blood Sugar These Days?

If you are an MD, I realize you’re not mine.

My doctor, who’s generally no fun and a scold (he’s just the right age to be of the Pritikin-era all-fat-is-evil school of mind, among many annoying traits) took me to task after a recent physical for having a fasting blood sugar of 102. He claims that’s within spitting distance of Type II diabetes (which I’m really not, IMHO, a candidate for based on my weight, ethnicity, etc.).

I’d always been raised to believe normal blood glucose was 80-120 mg/dl. He swears anything over 100 is “in the high range.”

Am I imagining what the range is/used to be, and/or has medical thinking/endocrinology changed on this topic?

According to the American Diabetes Association:

I’ve never had a doctor or any other medical professional say otherwise.

60-100 is what I was taught in nursing school.

F-ck. I get a headache whenever numbers come up.

First, if you are borderline, you need multiple measurements to come up with an average. I cannot fathom one measurement as being sufficient.

Yes, on paper, where you can draw a line, he is right. However, your one test result screams “do over”.

If your average works out to be borderline (just above 100)… then maybe you are low on insulin or slightly resistant. The human body doesn’t have a ‘yes’/‘no’ indicator lamp, so someone has to apply some thought to this. God forbid a doctor might do it.


I would take your doctor to task, not for thinking 102 is high, but for drawing a conclusion from just one reading. Even when fasting, blood sugar can be affected by many factors, and can change from one minute to another. I would not be at all alarmed at a 102 reading, but concerned enough to do additional testing.

Your belief about the normal range of blood glucose is incorrect. Your doctor is right to be concerned because you meet at least one of the diagnostic criteria for being what is considered pre-diabetic/ metabolic syndrome.

From the American Journal of Medicine ( June 2008 (Vol. 121, Issue 6, Pages 519-524):

“Subjects developed diabetes at a rate of less than 1% per year during a mean follow-up of 81.0 months. Each milligram per deciliter of fasting plasma glucose increased diabetes risk by 6% (hazard ratio [HR] 1.06, 95% confidence interval [CI], 1.05-1.07, P < .0001) after controlling for other risk factors. Compared with those with fasting plasma glucose levels less than 85 mg/dL, subjects with glucose levels of 95 to 99 mg/dL were 2.33 times more likely to develop diabetes (HR 2.33; 95% CI, 1.95-2.79; P < .0001). Subjects in the 90 to 94 mg/dL group were 49% more likely to progress to diabetes (HR 1.49; 95% CI, 1.23-1.79; P <.0001). All other risk factors except sex were significantly associated with a diabetes diagnosis.”

Basically, every full milligram above 85 you are (so 86, 87, 88…) increases your risk by 6%.

Unless you know the false-positive rate of the test, as well as Type I and Type II errors, it’s somewhat naive to demand an additional test. If there is a high rate of false positives, or if the OP were truly borderline higher risk (starting around 90 to most practitioners), then that would be another question. In this case, the OP is so obviously at an elevated risk, it would be a waste of resources to do another test.

To the OP, if you have the option of changing MDs, why don’t you? It sounds like your MD is difficult for you to communicate with and isn’s someone whose opinion you have much respect for. That’s not a good mix for managing health, with or without any additional blood sugar related issues.

To clarify, this is an increase in relative risk. So if he’s about 2.5 times more likely to develop diabetes in the next year as someone with a fasting glucose < 85, that means that rather than a vague “less than 1%”, his risk is “less than 2.5%”.

I don’t think that’s necessarily true. Diabetes can be diagnosed based on a single fasting glucose >= 126. The only time you need two measurements is for non-fasting glucose, IIRC.

Well obviously if the number is high enough a single reading is enough. Mine was over 300, so there was no doubt. But I’d say 102 would call for concern, whereas mine called for immediate serious intervention.

I think you’re confusing big picture with small picture.

Small picture- whether a particular blood glucose reading should be labelled “normal”, “pre-diabetic” or “diabetic”.

Big picture- whether small changes in diet and lifestyle could positively modify your risk factors for diabetes, heart disease and stroke.

Where I work, we used to have health screenings supplied by teams from local hospitals. Here’s what the guidelines say from 2002-2008 on fasting glucose:
2002: <115
2003: <115
2004: <110
2005: <110
2006: <100
2007: <100