WHAT IS INSULIN RESISTANCE?
Give brief summary – intro to insulin resistance AND hyperinsulemia (they are in tandem)
Example of insulin resistance is Type 2 diabetes. If you only learn one thing from this article, understand that in most cases, insulin resistance and hyperinsulinemia have been present and lurking for YEARS before someone is “officially” diagnosed as a diabetic.
In fact, if your doctor has told you that you’re “pre-diabetic” they should also be telling you that the reason is that your body is becoming insulin resistant due to chronically high levels of circulating insulin.
HOW DO WE DEFINE INSULIN RESISTANCE?
Doctors typically use blood glucose or blood sugar readings as a way to determine if someone is diabetic and insulin resistant. Measuring blood glucose levels is easy from a technology standpoint where a $30 home glucometer can tell you within 10 seconds what your blood glucose levels are. Continuous blood glucose monitors (CGM) allow for minute-by-minute tracking of circulating glucose levels as well.
However, we currently don’t have a great method of instantly measuring circulating insulin levels. You doctor can order a “fasting insulin” blood test, but that typically requires a visit to the lab or the doctor’s office and blood drawn from a vein and sent off to the lab for analysis.
But if you know your fasting insulin and glucose results, you can calculate your HOMA-IR score (Homeostatic Model Assessment For Insulin Resistance which can give you an indication of oil you are insulin sensitive or insulin resistant.
Read more about the HOMA-IR score here.
Take Home Point #1
Insulin Resistance is a cell’s INABILITY to respond NORMALLY to the presence of insulin.
Take Home Point #2
Insulin Resistance means there’s also elevated levels of insulin in the blood (hyperinsulinemia)
Take Home Point #3
Type 2 Diabetes is insulin resistance that has progressed to the point where blood glucose levels start to rise above normal levels
Take Home Point #4
You can be insulin resistant and still have normal blood glucose levels
You can have normal glucose levels on your annual physical exam blood tests, but years of hyperinsulinemia before you become clinically insulin resistant (ie rising blood glucose)
One way I try to explain this concept to patients is using a “smoke and fire” analogy. If you pull into your driveway and you see smoke billowing out of the windows, you’re not going to wait until you actually see flames and fire before you call the Fire Department.
Or if after a heavy rain storm, you notice a small wet spot in the ceiling, you’re (hopefully) not going to wait until a few more storms have have the leak worse where the ceiling needs to be replaced.
HOW DO WE BECOME INSULIN RESISTANT?
Should I blame my parents? Genetics causes of insulin resistance and diabetes
Fortunately for mom and dad, the genetics part of insulin resistance probably plays a lesser role than previously thought, but can still play an underlying role in the development of insulin resistance.
Does ethnicity play a role in insulin resistance?
Ethic heritage may play a role in developing insulin resistance, 1 but again, genetics are probably not the only reason someone develops insulin resistance and in many cases, Type 2 diabetes.
The “thrifty genotype” 2 has been blamed as one reason for higher incidence of insulin resistance in certain populations such as Pacific Islanders from Naura 3 or the Pima Indians in Arizona 4 but the “thrifty genotype” has still yet to be proven. This theory suggests that certain ethnic populations evolved a “thrifty genotype” that made it easier for them to survive periods of famine or limited food supply by being better able to store calories as fat.
One important issue with the development of insulin resistance in these groups could be the recent introduction of the “Western diet”, high in refined carbohydrates such as flour and sugar, into these populations with the “thrifty genotype” where we see these populations struggle to adapt to a diet much different than their ancestral diet. As these populations have become exposed to more consistent and plentiful food sources, these “thrifty genes” may actually act as a hindrance when these groups start to adopt a “Westernized” diet.
The cause(s) of Insulin resistance
It would be easy to just blame excess refined carbohydrates as the ONLY cause of insulin resistance, but there are other factors that are also to blame for insulin resistance.
Cortisol – The Stress Hormone and Insulin Resistance
Cortisol and epinephrine make up part of our “flight or fight” response which probably played a big role in survival during our hunter-gatherer times, however, the acute cortisol and epinephrine surges during those times have now been replaced with chronic elevation of stress hormones. This chronic elevation of cortisol and epinephrine also lead to cells becoming more insulin resistant.
Another down side to chronic cortisol levels is that elevated cortisol levels also can lead to an increase of visceral fat instead of subcutaneous fat. Increased visceral fat tends to increase your risk of insulin resistance, diabetes as well as heart disease.
Your Thyroid and Insulin Resistance
Having an underactive thyroid (hypothyroidism) can also have an effect on insulin resistance. Low thyroid levels can result in a decrease in the number of insulin receptors on the surface of the cell, reducing the effect of insulin on that cell. If insulin can’t find an insulin receptor to bind to, insulin can’t signal the cell to activate its glucose-transport systems to let some of the circulating blood glucose into the cell.
Is Insulin Resistance just about carbohydrates?
Insulin resistance is probably not just carbohydrate intake. While it’s easy to demonize all carbohydrates, the focus should probably be on refined and highly processed carbohydrates like table sugar, fructose and other highly processed carbohydrates like white flour.
Going back to the “thrifty genotype” populations, many of these populations had diets high in starchy and high-fiber carbohydrates such as tubulars and other root vegetables prior to their development of insulin resistance and diabetes on a more refined carbohydrate diet.
- Zimmet P, Arblaster M,Thoma K.The effect of westernization on native populations. Studies on a Micronesian community with a high diabetes prevalence. Aust NZJ Med 1978;8:141-6[↩]