Think Skinny People Don't Get Type 2 Diabetes? Think Again. | Chris Kresser

Think Skinny People Don’t Get Type 2 Diabetes? Think Again.

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In the last article on diabesity and metabolic syndrome, we discussed the complex relationship between body weight and type 2 diabetes (T2DM). We learned that although obesity is strongly associated with T2DM, a subset of “metabolically healthy obese” (MHO) people have normal blood sugar and insulin sensitivity and don’t ever develop diabetes.

In this article we’re going to talk about the mirror reflection of the MHO: the “metabolically unhealthy nonobese” (MUN). These are lean people with either full-fledged type 2 diabetes or some metabolic dysfunction, such as insulin resistance.

You might even be surprised to learn that skinny people can and do get T2DM. They are rarely mentioned in the media, and there isn’t much written about them in the scientific literature.

Perhaps these folks have been overlooked because type 2 diabetes has been historically viewed as a disease of gluttony and sloth, a self-inflicted outcome of eating too much and not exercising enough. But the very existence of the MUN phenotype proves that there’s more to T2DM than overeating and a sedentary lifestyle.

Remember that one in three type 2 diabetics are undiagnosed. It’s possible that a significant number of these people that are lean. They don’t suspect they might have T2DM because they’re under the impression that it’s not a condition that affects thin people. This is one of the biggest dangers of the myth that “only fat people get diabetes”.

It’s well-known that high blood sugar can precede the development of T2DM for as long as ten years. It is during this time that many of the complications associated with diabetes – nerve damage, retinal changes, and early signs of kidney deterioration – begin to develop. This is why it’s just as important for lean people to maintain healthy blood sugar as it is for the overweight and obese.

It’s also important to understand that diabetes is not a disease. It’s a symptom. Every single person with T2DM, whether they are rail thin or morbidly obese, shares a single symptom: high blood sugar. Therefore, anything that interferes with the body’s regulation of blood sugar levels will cause type 2 diabetes.

What Causes High Blood Sugar and T2DM in Lean People?

Not surprisingly, the causes of T2DM in lean people are similar to the causes of T2DM in the obese. They can be loosely grouped into the following categories:

  1. Genetics
  2. Fatty liver
  3. Inflammation
  4. Autoimmunity
  5. Stress

Let’s discuss each of them in turn.

Genetics

Studies of the lean, otherwise healthy offspring of type 2 diabetics has revealed that they are much more likely to be insulin resistant than the lean offspring of non-diabetics. One explanation for this is an inherited defect that causes mitochondrial dysfunction. People with this defect are not able to burn glucose or fatty acids efficiently, which causes lipotoxicity and an accumulation of fat inside of muscle cells.

I will discuss the contribution of genetics in more detail in the next article. What I want you to understand here is that the genetic mechanisms I described above are capable of causing insulin resistance and high blood sugar independently of overweight or obesity.

Fatty Liver

Studies of lean, Asian Indian men have found that they have a 3- to 4-fold higher incidence of insulin resistance than their caucasian counterparts. They also have a much higher prevalence of non-alcoholic fatty liver disease (NAFLD) and hepatic (liver) insulin resistance.

NAFLD is an independent predictor of type 2 diabetes. Cross-sectional studies have shown that fatty liver and metabolic abnormalities occur together. It has also been proposed that fatty liver is not just a result, but also a cause of insulin resistance and type 2 diabetes.

Now, keep in mind that these Asian Indian men with NAFLD were not overweight. They were lean, and in some cases, even underweight. This proves that NAFLD occurs in lean people, and together with the evidence above, suggests that NAFLD may be a primary cause of insulin resistance and T2DM in lean people.

If you’re thinking NAFLD might be a rare problem confined to Asian Indian men, you should know that up to 30% (almost 1 in 3) of people in industrialized nations suffer from it. This is a disturbingly high prevalence of a condition that is known to progress to severe liver inflammation and cancer in a small percentage of people – in addition to contributing to T2DM and metabolic syndrome.

While there may be a genetic component that predisposes people to developing NAFLD, we also know that dietary factors play a significant role. Rodent studies have shown that feeding large amounts of sugar and industrial seed oils (like corn, safflower, sunflower, etc.) promote NAFLD, whereas saturated fats such as butter and coconut oil do not. And in human infants, tube-feeding with industrial seed oils causes severe liver damage, whereas the same amount of fat from fish oil does not.

Fructose, especially the high-fructose corn syrup (HFCS) found in sodas, candy and several packaged and refined foods, is perhaps the most significant dietary cause of NAFLD. The liver processes fructose by converting it to fat. The more fructose consumed, the more fatty the liver becomes. Feeding rodents high amounts of fructose promotes NAFLD, and the consumption of soft drinks (by humans) can increase the prevalence of NAFLD independently of metabolic syndrome.

Let me say that again: high fructose intake can cause fatty liver disease independently of overweight, obesity or type 2 diabetes. Do you think that might be a problem in a country where soft drinks account for nearly 10% of total caloric intake?

Since fructose is handled by the liver in the same way the liver handles alcohol, excess fructose produces a similar range of problems as alcohol abuse: hypertension, high triglycerides and low HDL, obesity, cirrhosis and insulin resistance.

Inflammation

In the study of lean Asian Indian men above with T2DM, it was found that they had a 2-fold increase in plasma levels of the inflammatory protein IL-6 when compared to lean subjects without T2DM. In a previous article I showed that chronic, low-grade inflammation associated is an important mechanism in decreasing insulin signaling and causing insulin resistance in muscle, liver and fat cells.

Also, inflammation has been shown to precede the development of diabetes. Infusion of inflammatory cytokines into healthy, normal weight mice causes insulin resistance, and people with other chronic inflammatory conditions are at higher risk of developing T2DM. For example, about one-third of chronic Hepatitis C patients develop T2DM, and those with rheumatoid arthritis are also at higher risk.

Autoimmunity

Up until recently, type 1 and type 2 diabetes were seen as distinct entities. It was understood that type 1 diabetes (or insulin-dependent diabetes) was caused by autoimmune destruction of the beta cells of the pancreas, leading to decreased insulin production, whereas type 2 diabetes was caused by insulin resistance of the liver, muscle and fat cells.

However, recent research has demonstrated that the line separating these two conditions may be much blurrier than previously thought. It is now known that type 1 diabetes, which normally begins in childhood, may slowly develop later in life. This form is referred to as latent autoimmune diabetes (LADA) or more informally as type 1.5 diabetes.

Studies suggest that type 1 diabetes in adults is frequently misdiagnosed as T2DM, and up to 10% of adults with T2DM may actually have the autoimmune form.

Even more relevant to this article is the finding that fully 1 in 4 lean people with T2DM produce antibodies to GAD, the same enzyme in the pancreas that is attacked in type 1 autoimmune diabetes.

These findings suggest that a significant number of lean people with T2DM may be suffering from autoimmune diabetes. This will obviously require a different treatment strategy than those who have the non-autoimmune form. (The way to find out whether you’re in this group is to have your GAD antibodies tested. It’s a fairly standard blood test and is available through Labcorp and Quest.)

(Interestingly enough, approximately 5% of patients with autoimmune thyroid conditions also produce antibodies to GAD. So if you have Hashimoto’s or Graves’ disease along with blood sugar symptoms that don’t respond to dietary changes, you should have your GAD antibodies checked.)

Stress

Under conditions of stress, the body produces higher levels of the hormone cortisol. Cortisol plays a number of important roles, but one of it’s primary functions is to raise blood sugar. This is an incredibly helpful evolutionary mechanism that is part of the “fight or flight” response that prepares us to deal with a challenge or threat.

However, that mechanism was only designed for short bursts of stress.

Chronic stress as we experience it today – like worrying about getting audited by the IRS, driving in traffic, and suffering from degenerative disease – wasn’t part of our early ancestors’ lives. This means that our bodies aren’t prepared to deal with the effects of chronic stress, which include chronically elevated levels of cortisol.

Why? Because cortisol is capable of raising blood sugar to unhealthy levels even when a person is fasting. What that also means is that you can be lean, eat a perfect diet, and still have high blood sugar (and thus T2DM) if you suffer from chronic stress. I’ll be writing more about the connection between stress and diabetes in a future article.

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  1. I have a question?? I’m 5’2″ 125lbs. my morning fasting blood sugar has been between 100-110 for several weeks. I didnt have this problem before?? I’ve recently lost weight (in the last 6months) ?? I figured it was due the diet change…

    I have Hashimotos and a lot of food intolerances… I avoid SOY-GLUTEN-DAIRY-YEAST-CORN-RICE-POTATO….

    I have honey in my morning coffee… I eat very clean…

    Is it the honey?

    doesn’t make sense to to me?

  2. “Since fructose is handled by the liver in the same way the liver handles alcohol, excess fructose produces a similar range of problems as alcohol abuse: hypertension, high triglycerides and low HDL, obesity, cirrhosis and insulin resistance.”

    Here it is a good idea to define “Excess Fructose” because several hundred grams of fructose can be stored as glycogen in the liver before it even starts converting any of it to fat.

    When you say “Excess fructose” I assume you mean unphysiological amounts where it pushes you to a calorific excess? As anything else (Especially when that fructose is derived from fruits) none of the above issues would occur.

    I just feel the point needs to be clarified as the last thing I think you would want to do is scare people off eating plenty of fruit as a part of their daily calories.

  3. Prior to getting pregnant, I was diagnosed with controlled type 2 diabetes (I am 29, 5’5″ and 130 lbs – active). I was diagnosed because of previous miscarriage at 8 weeks and a chemical pregnancy – I have insulin resistance due to PCOS. My a1c was 5.4% (normal). I started taking 500 mg of metformin in the morning and got pregnant the next cycle. I am currently 5 weeks 3 days. My morning fasting numbers have slowly been increasing from mid-low 80’s to 94 today. I am also eating very low carb and have been for about 2-3 months (30-45 g carbs/day and almost all from veggies). My post-meal glucose levels are all low (in the 80’s and 90’s).

    Any suggestions for getting my fasting numbers down to a healthier level?

  4. I was always skinny until I had children. I also was hypoglycemic.
    Now I have moderately high blood sugar – gets up to 150 if I forget to take metformin and I am overweight. I feel so bad that I am not skinny anymore. I don’t recognize myself in the mirror. What happened?

  5. Hi,
    I am a 54-year old slim man (BMI 20), with a good diet and lots of exercise. I don’t smoke and I drink in moderation. For about 15 years, I have been taking statins to control my cholesterol and calcium channel inhibitors, other meds to control blood pressure and reduce chest pain from cardiac syndrome x and asprin to reduce risks of CHD in general. A few years ago I also discovered that I had hyperhomocysteinaemia – 50μMols/L, for which I take folic acid and vitamin b complex. Now my cardiologist tells me that I have rising blood sugar (95 and 99 mg/dL fasting at the last two tests), and is very interested in my skin problems, gum disease, hay fever, nosebleeds etc. It seems that I have mild generalised inflammation and may be developing insulin resistance.
    The cardiologist will obviously monitor the situation, but for now his advice is 1) more exercise, 2) more exercise and 3) less carbohydrate intake.
    I am following this, but as I say I am already slim, with a good diet and lots of exercise. Almost all the advice aimed at heading off diabetes talks about losing weight and changing your sedentary lifestyle. What more can those of us who can’t lose weight and do not have a sedentary lifestyle do?

    Alan

  6. Type 2 diagnosis @ age 64. Turn 66 2wks. Never overweight: heaviest ever @ 136 lb. never over 120 until 45 yrs old. 5’8″. Always very active & have always eaten right, growing much of my own food. Most people think I’m age 45-50, by appearance. Mother in mid-90’s no problems. Sisters both fine, even the overweight one. (I’m middle of 3 girls.) So why, why, why? On Metformin 500 mg qd, fasting glucose stuck at 108-110. A1c running stuck 5.6-5.8. VERY discouraged. Women in my family 5 gens make it to late 80s at least, usually 90s. Seems like no hope for me in spite of strict care…

    • Hi MAS,
      Don’t fret. Type 2 diabetes is not the worst thing that could happen. If you stay active and continue to eat right (as you are already doing) and definitely stay compliant with your medications, your DM should stay well-controlled. What you want to avoid are the complications of DM. If you want to lower your A1c try shaking things up with your exercise routine, perhaps your body is used to your current workout and your body needs to be challenged in a different way than it is used to. I don’t know what your current routine is but increasing aerobic exercise is a good way to go, even if you’re already doing aerobic exercise now, just trying stepping it up. Anyway, sorry to go on and on, it’s just that I saw your post and thought I would try to share some encouraging words.

  7. I am skinny and type 2 diabetes but want to know if there is anything I can do to stop getting any thinner I am 5 ‘ 8″ and 136 lbs

    • Hey Jayne, the only way you will be able to gain weight is to eat more carbs. It will lower the amount of fat you burn. I just happened on here but thought I would give you my input. I am type 1.

  8. IFCC (International Federation of Clinical Chemistry) is MMOL/MOL whereas the traditional HbA1c in the UK, is a percentage. I understand that from June 2011 the UK is switching to IFCC.

  9. My functional range only goes up to 5.2. Studies clearly show that heart disease risk increases in a linear fashion as A1c moves above 4.6. From 4.6 to 5.2 the increase is small, but after 5.3 it begins to go up considerably.

  10. Maybe it was a functional range of 4.8 to 5.9? Though a functional range would be more likely to be up to 5.3 or 5.5.

  11. I was guessing the decimal was in the wrong place, i.e. 4.8 – 5.9, but that still doesn’t make a lot of sense.

  12. You’re not misunderstanding anything according to the conventional model, but keep in mind what a spectacular failure that model has been. Diabetes and heart disease are epidemic, and getting worse. My advice is not to follow their advice, because their advice is obviously not helping. The stats don’t lie.

    The laboratory ranges are simply bell curves of the results of people who get tested. And who gets tested? People who are sick. Therefore the lab ranges don’t reflect what’s optimum for health, but instead what is average for sick people.

    • Can you tell me where I can find a good, simple book with basic meal plans based on what you’re saying? I seem to have everything you’ve mentioned – fatty liver (many yrs ago and nothing was said about it). Meed to lose 100 lbs. chrinic pain head to toe. Dx’ed w type 2 diabetes 1.5 yrs ago. How many carb grams a day do u recommend? If I test 2 hrs post eating what # am I trying for? I was also told a 7 a1C was my target! What does one eat to fix a fatty liver? I desperately need to change. Thanks for any help.

  13. Chris.

    Thanks for that. I’ll see what I can do to reduce further…

    Just 1 thing. On my last test it was 6.6. The document from the laboratory also provided it as (IFCC) which was 48.6.
    In that document they state that the normal range is (48 – 59) which would put me at the low end, or have I misunderstood something ?

  14. I doubt he’s lying – it’s possible an A1c of 7 is the best of his patients. But that’s hardly “good control”. Many T2DM patients can get their A1c down in the 5s with a low-carb diet and, in some cases, a relatively low dose of metformin. An A1c of 7 is too high, as evidence suggests that complications begin as A1c climbs above 5.4. I’ll be writing about this very soon.

  15. Lynn.

    Thanks, I’ll take a look.

    Chris.

    A1c of 7 is high ?
    My doctor has told me that 7 is the best of all his type 2 patients.
    Is he talking rubbish ?

  16. Yes, Tim, an A1c of 7 is alarmingly high. It’s not something to “maintain”, but something to address as if your house is on fire (which it is, in a manner of speaking).

  17. At 18 went to my GP with indigestion. Every night my sleep was disrupted and I was guzzling antacids. I was checked for ulcers and later Celiacs Disease and the verdicts were both negative.
    I lived with this for 35 years and was diagnosed as diabetic when having a standard blood test due to my age.
    I have been managing my blood sugar quite well for 5 years now simply with diet. I test my blood sugar level 2 hours after meals and adjust my next meal accordingly.

    Now the interesting bit…
    During this period I have experimented with various foods and have discovered that my indigestion problem completely disappears when I cut out wheat products. In addition my blood sugar is much easier to control and I can even eat ice-cream and have sugar in my tea and still maintain an HbA1c of 7.