You can't tell if someone is diabetic simply by looking at them.
Yet a lot of people still think you can. They buy into the idea that eating too much and exercising too little causes obesity and obesity causes type 2 diabetes. Hence, if shown a bunch of photos of strangers, many would predict that the fat ones had diabetes and the thin ones didn't.
It is true that being overweight is associated with type 2 diabetes, and many people with the disease are, in fact, overweight. But not everyone who is overweight, or even obese, has diabetes, and not everyone who has type 2 diabetes is overweight.
While filing sometime recently, I came across a popular press article that I had found fascinating.
A British newspaper had asked 10 people between the ages of 35 and 50 who had never been diagnosed with diabetes to take "a blood test." The test was simply a fingerstick test in a home-type meter. If the participants said they hadn't eaten (most likely not rigorously controlled, so it wasn't a real fasting test but closer to a premeal test), any result over 5.9 mmol/L (106 mg/dL) was considered suggestive of diabetes. If they said they'd eaten recently, the cutoff was 8.9 mmol/dL (160 mg.mL).
If the results were over these limits, the people were told to see their physician for more rigorous tests. They don't say which readings were premeal and which were after eating, so one person with a reading of 8.9 mmol/L (160 mg/dL) was labeled diabetic and another with a reading of 9.1 (164 mg/dL) was labeled "needs investigation." Probably the former reading was premeal and the latter was after eating.
Here's the interesting part. They then photographed the participants wearing gym togs, so you can compare their body builds with high blood glucose (BG) readings. It's also interesting to compare the body builds with the BMIs.
In this tiny sample, there were a lot of results that go against "common knowledge."
One person labeled obese (BMI 34) had normal BG levels. A person with a BMI of 22 had high BG levels. A woman with a pear shape, which is supposed to be healthy (it's the apple shape with most of the weight in the stomach that is thought to be dangerous), had high BG levels. A woman with a lot of risk factors had normal BG levels. A vegetarian was obese. And the woman with the lowest BG reading said she got no exercise at all.
Scroll down through the initial text, which is the usual popular press stuff about diabetes, and try looking at the photos before you read the descriptions underneath them to see how your predictions compare with the facts.
Many of these participants had relatives with diabetes, which is probably one reason they volunteered for the tests. And they were relatively young. Some of those who tested normal with this fairly uncontrolled test may develop diabetes when they get older.
But it's still interesting to see how different people are and how misleading body build can be as a predictor of diabetes.
The sad thing is that because of the constant barrage of news stories saying that obesity is the cause of type 2 diabetes, many people (probably most people) believe it. And that includes a lot of physicians, who might not bother to do BG tests on someone who was thin, said they "ate healthy" (whatever that means), and got regular exercise.
With the advent of home meters, it's easy to test friends and relatives if you think they might be at risk. Just make certain you use fresh lancets when you do, as well as cleaning off the tip of the finger pricker, to avoid passing on any blood-borne diseases. Even better, ask them to get their own finger-pricking devices.
Because type 2 diabetes usually starts with elevated postmeal BG levels, measuring after a large meal, especially a carby meal, would be the best place to start. People can have normal fasting BG levels and elevated postmeal levels for years before they get a diagnosis. The earlier they learn they're at risk, the easier it will be to take corrective action, like limiting the carbohydrate content of their meals.
And if you are testing relatives, don't ignore the thin ones who exercise. Diabetes is a complex disease, and it happens to apparently healthy people too.