Insulin resistance causes weight gain and then type 2 diabetes as I’ve said in my book, The New Diabetes Prescription. To be diabetic or pre-diabetic is to have insulin resistance 100% of the time. But what exactly is insulin resistance? How does it lead to weight gain? How does that then lead to diabetes? And how can it be prevented? I’ll answer all that in this 3 part series on the causes of diabetes.
Insulin is excreted by the pancreas after the first bite of food, and later on in boluses, or little squirts, to keep blood sugar stable. Among the three major nutrients, carbohydrates require far more insulin to process than protein or fat. In fact, fat eaten without any carbohydrates barely requires any insulin at all. To summarize, you eat, glucose is processed, and insulin transports that glucose to your cells so they can eat. Insulin resistance requires more insulin than normal to make that whole process work.
The amount of insulin needed to process a gram of glucose into your cells is not fixed. It varies from person to person, and even hour to hour! People who need very little insulin to process their food are called insulin sensitive. Insulin sensitivity is increased with exercise, eating healthy, having more muscle, and keeping lean.
In contrast, overweight people and type II diabetics have insulin resistance because they may need up to four or more times the amount of insulin of a normal individual to process their food. Insulin resistance is increased through not exercising, eating a diet high in refined sugars and fats, and as a consequence, gaining too much body fat. These actions and subsequent fat gain cause huge surpluses in glucose that must be cleared from the blood by huge surpluses in insulin.
Excess blood sugar causes glycation, the unintended bonding of sugar with proteins and lipids. Picture billiard balls bouncing around on a pool table, smashing into each other, but every time they do, the balls stick together. This haphazard bonding creates what are known as advanced glycation end products (AGEs) and free radicals that wreak all sorts of havoc in the body, leading to diabetes and a host of other degenerative diseases. AGEs damage the beta cells, causing even higher blood sugar and insulin resistance. They damage the endothelial lining of the blood vessels, causing plaque to form in the larger arteries. This stiffens the arteries, causing atherosclerosis, putting you at risk of a heart attack or stroke. Glycation also stiffens the collagen in blood vessels, increasing blood pressure and these risks even further. And since glycated cells are cleared very slowly from the body, the kidneys, eyes, nerves, and DNA are damaged over time.
Interestingly, not all forms of sugar cause the same degree of glycation. Fructose found in fruit, fruit juice, and soda, and galactose–found in dairy products–are far more glycating than straight glucose. In fact, fructose causes ten times the glycation compared to glucose. It shouldn’t be surprising then that sodas and other products containing high fructose corn syrup are linked to obesity and diabetes.
Excess insulin in the blood causes insulin resistance by destroying the GLUT4 insulin receptors on the exterior of cells. These receptors actually move glucose into cells without the help of insulin. As a side note, these GLUT4 receptors are why exercise is awesome for diabetics – just moving around can get glucose into your cells without any insulin at all! However, losing your GLUT4 receptors means even less glucose can get into the cells, forcing the body to produce even more insulin. With each increase in insulin, more insulin receptors are damaged, and the process ensues. Glucose that cannot enter the muscle cells will be diverted to the fat cells, making them larger. Further, all that extra insulin severely blocks hormone-sensitive lipase (HSL), the enzyme that breaks down body fat.
So the more insulin circulating through your system, the more fat you’ll gain, especially in your gut. Have you ever noticed people who are stressed, have heart problems, or have diabetes tend to carry most of their fat around their middle? Diabetics and pre-diabetics often have an “apple-shaped” build, where fat is concentrated in the abdomen rather than through- out the entire body. There is a very good reason for this. It’s the center of your body and home to a kind of fat that surrounds your internal organs, known as visceral fat. This special kind of abdominal fat is responsible for a pot belly. It’s different from the fat you can pinch around your belly button, love handles, buttocks, or thighs – that is, fat just under the skin, dubbed subcutaneous fat.
Visceral fat is full of toxins and hormones that, due its close placement near internal organs, can be easily released directly into your bloodstream and liver. All that excess fat releases abnormal amounts of hormones and chemical messengers like cytokines that cause inflammation to your endothelial tissue, the thin lining around blood vessels that helps transport nutrients into cells. These inflammatory markers also distort how insulin interacts with your fat and muscle tissue, further increasing insulin resistance. For this reason, visceral fat is regarded as a marker for cardiovascular disease and diabetes. Just having a large waist circumference greater than forty inches in men and thirty-five inches in women increases your likelihood of having a heart attack or stroke.
Visceral fat’s close proximity to the liver also contributes to non-alcoholic fatty liver disease (NAFLD). The excess fat that’s been created causes the liver to overproduce triglycerides, cholesterol, and even more blood sugar, exacerbating insulin resistance even further.
Once all these problems are in place, you still may not be a full blown diabetic. You may only have insulin resistance and a weight problem. The body is still putting up a fight against the invasion of excessively high blood sugar levels by manufacturing an army of insulin to clear it all from the blood. Unfortunately, it’s a lot easier to create more glucose than it is to manufacture more and more insulin. After all, all it takes to make more glucose is another doughnut! If you continue to not exercise, and eat a diet high in calories from refined flour, sugar, and saturated fat, the loser will be your pancreas. It will fail to produce enough insulin to clear glucose from the blood, and your blood sugar will rise. The breakdown will happen in two stages, leading to diabetes. Initially, your pancreas stops releasing the first big bolus of insulin with the first bite of food. It then tries to “make up” for the lack of first response by excreting too much insulin after the meal. With this response, your blood sugar swings wildly from too high to too low, causing hunger and carbohydrate cravings. Acting on those cravings only makes fat gain, insulin resistance, and pancreatic exhaustion worse. In the second stage, the pancreas will stop producing and releasing as much insulin in boluses after eating. Blood sugar will invariably be high enough now to diagnose you with diabetes. The pancreas may completely stop producing insulin. You may need insulin injections, as much as four times the normal amount for someone of your weight, to counter the insulin resistance. This is the last stage in the development of type II diabetes.