I've got a young, lean brother (BMI 20) who has developed insulin resistance and type 2 diabetes, much like the study in the opening post. I found another study of young lean men developing insulin resistance from OSA, and it's pretty small sample size, but feels relevant for my brother's case.
He is trying to lose weight in the hopes it will cure his diabetes, and when I brought up sleep apnea to him he told me "only people above BMI 30 develop it" sigh. he's now eating veganish and as close to zero carb as possible, so basically almost no food at all and it's concerning.
my brother's endocrinologist didn't bring up sleep apnea during his appointment and it makes me angry. How does a young, lean dude who suddenly developed high blood sugar and doesn't have the antibodies for type 1 diabetes not trigger an immediate sleep study? Why don't more doctors look into sleep issues as a source of health problems? it makes you really angry if you think too hard about it.
People who are lean and highly insulin resistant (in other words pre-diabetic or a type II diabetic) are sometimes described by the acronym "TOFI" or "thin on the outside, fat on the inside", the fat is usually around the organs, and most notably TOFI's often have fatty liver disease.
Weight loss is the mantra of the endocrinologists who seem to think that people cause their insulin resistance by "allowing themselves" to become fat--clearly not the case for your brother. I have a daughter who is now 18 and she weighs 81 lbs with all her clothes on--she is very petite as well, but that's about a BMI of about 16%. Yet she is highly insulin resistant (with severe PCOS she inherited from me) and her first (and quickly fired) endocrinologist told her at 13 the best way to treat this condition was to lose weight
--she can't afford to lose an ounce (and that NEVER should have been said to a vulnerable teenage girl!!!) More recently her current endo almost called child protective services on me last year because she used to weigh 88 lbs--almost a 10% loss of body weight (caused by stress, not by her parents starving her!) Her insulin resistance and PCOS are no better despite the 10% loss in body weight, BTW, so weight loss is clearly not the answer for her.
I just cannot imagine what vegan food would also be "close to zero carb" unless unless your brother is drinking olive oil as his main food, and malnutrition certainly isn't the answer either.
Caution--rude generalizations ahead! I once had a wonderful endocrinologist, but for the most part they are arrogant pricks. Sleep apnea is first of all "not their department" and secondly, they are usually such big fat shamers that they would never even consider it for a skinny guy like your brother--he doesn't fit the profile. Many women and thin men are overlooked for testing because they don't fit the stereotype of what a sleep apnea patient should look like. His endo is clearly assuming he doesn't have sleep apnea because he's thin.
My guess also is that your brother didn't "suddenly develop high blood sugar". It was probably there all along, but not recognized because who would even bother testing a skinny guy??? Elevated glucose comes long after years--more like decades-- of insulin resistance, and they don't EVER test for insulin resistance, even if someone presents with symptoms like "reactive hypoglycemia" or acne or signs of PCOS in teen girls (my daughter only got tested because i recognized the symptoms and had to fight her doctor to order the tests--when they came back showing severe PCOS and insulin resistance, her doctor at least had the grace to call me and apologize for resisting my request for testing).
There is definitely a hereditary component to hyperinsulemia, insulin resistance, diabetes. But the ancestors who gave us that DNA rarely if ever had diabetes. The change is in the environment and in the food that we have been drilled into thinking is healthy that pulls the trigger on the gun DNA loaded.
Your brother's idea to limit carbs would be a good choice IF he was eating adequate natural (not processed) fats and sufficient protein. But otherwise I agree with you that it's very dangerous. Some people get it when their teeth start falling out, some people dig in and suffer the health consequences.
