The Connection Between Type 2 Diabetes, Obesity, and Insulin Resistance

"The real heart of type 2 diabetes is insulin resistance"

(Fung, Insulin Toxicity and How to Cure Type 2 Diabetes). Studies show at least 285 million people in the world have type 2 diabetes (T2D). T2D is growing at an epidemic scale worldwide. By 2030, scientists expect T2D to affect around 500 million people globally (Gustafson). Researchers, scientists, and doctors are trying to understand and prevent this catastrophic disorder. People all over the world could reduce the chance of developing type 2 diabetes (T2D) by understanding that overconsumption of processed carbohydrates leading to the body's defense mechanism of insulin resistance is followed by the increased production of fat cells and eventually, induces obesity which is the primary risk factor for type 2 diabetes.

Until recently, scientists believed the symptoms of type 2 diabetes (T2D) were caused because the pancreas stops producing enough insulin, resulting in ever higher blood sugar levels. Current research links increased insulin levels to the insidious development of insulin resistance (IR) as the underlying cause of T2D (Mann). Insulin is an important hormone released by the pancreas that plays a major role in the proper function of the body. One of insulin's major functions is to keep blood sugar levels under control. As a person ingests food, insulin, which is released from the pancreas, moves blood sugar from the bloodstream into the cells to be used for energy.

Science shows that a calorie is not a calorie and not all types of foods provoke the same insulin response from the pancreas. Dr. David Ludwig states, "We know that excess insulin treatment for diabetes causes weight gain, and insulin deficiency causes weight loss . . . and of everything we eat, highly refined and rapidly digestible carbohydrates produce the most insulin" (Spell). For example, easily digestible, high glycemic, refined carbohydrates such as white bread, pasta, cereal grains, starchy vegetables, table sugar, and high-fructose corn syrup will cause blood sugar to spike which increases insulin production above normal levels. Occasional, spikes in blood sugar are manageable by the body. The release of small bursts of insulin brings the blood sugar back to normal or puts the body back into homeostasis - a state of internal equilibrium. Frequent or continuously high blood sugar causes levels of insulin to go up and stay up. To achieve homeostasis, the body begins to change to protect itself from the long-term excess insulin levels.

Dr. Jason Fung explains the process with effective metaphors. Insulin moves sugar from digested food into cells to be used for energy that is needed for immediate cell function. Excess sugar is turned into glycogen in the liver and is used for quick energy between meals. Dr. Fung compares this process to a wallet. Money moves in and out of a wallet easily. Glycogen moves in an out of the liver easily, but the supply is limited. When the body has too much glucose for the liver to process into glycogen, the insulin turns the glucose into fat cells. Fat is like money in a bank account. It is harder to access, but there is unlimited storage space for money in the bank. Likewise, the body has unlimited space to store fat. From here the process becomes more complicated (Fung, Insulin restistance protects against . . . insulin! T2D).

Diabetes involves several mechanisms in the body at once and is known to be a systemic disease. Dr. Fung describes the process of insulin resistance in a parable he calls Diabetesville. In the parable insulin is a delivery man driving a truck carrying glucose through the body. Each cell in the body is a house in the town of Diabetesville. The delivery man stops at each house and delivers a cup of glucose. If there is anything left at the end of the route, the delivery man takes the truck to the liver and the liver processes the glucose into glycogen. The glycogen is the money in the wallet (Fung, The Obesity Code: Unlocking the Secrets of Weight Loss).

As the person eats more insulin provoking foods, the delivery man drives by more frequently and instead of delivering a cup full of glucose, tries to deliver huge barrels of glucose. This symbolizes the increasing high levels of insulin in the blood stream. Hoping the delivery man will find a new place to dump glucose, the homeowner bars the door. The delivery man leaves the glucose outside hoping some will find its way inside. The glucose makes the houses rot and stink and is toxic at those excessive levels. Barring the door is insulin resistance. When IR occurs, fat cells accumulate. Fat cells are where the delivery man eventually dumps the toxic levels of glucose. The first fat cells are created in the liver and in the pancreas. These fat cells in the liver and pancreas change the way those organs function. Once the liver and pancreas are full of fat cells, the insulin delivery man starts dumping or creating fat cells in other parts of the body and the person starts gaining weight.

Insulin resistance is demonstrated by an expanding waistline due to the development of fat cells. The NIH research states that "a waist measurement of 40 inches or more for men and 35 inches or more for women is linked to insulin resistance and increases a person's risk for type 2 diabetes" (Center for Disease Control (CDC)). Before the body begins to show signs of weight gain, insulin pushes excess glucose into the liver and pancreas where fat cells begin to build up (Fung, Insulin Toxicity and How to Cure Type 2 Diabetes). The liver stops sensing the rise and fall of the hormone, glucagon. Under normal conditions, glucagon is released from the pancreas to alert the liver to release glucose from glycogen stores (money from the wallet) into the blood stream between meals to keep cells alive. Because the liver no longer senses glucagon, it will continually push out glycogen in an effort to keep blood glucose levels high enough to stay alive (American Association of Diabetes Educators). This causes the pancreas to release more insulin to bring blood glucose levels down to normal levels, which is another cause of excess insulin levels that lead to insulin resistance.

In 1993, a study was published in Diabetes Care Journal which showed that insulin injections can control blood glucose levels in people with T2D. In the study, subjects with T2D were given insulin to bring down their blood glucose levels. At the beginning of the study it took an average of 86 units of insulin per day to keep their blood sugar in control. Six months later, the average amount of insulin needed was 100 units per day. While blood sugars were controlled, insulin resistance worsened, and the subjects gained an average of 19 pounds (Henry).

A rare tumor called insulinoma causes rapid increases secretion of large amounts of insulin in the body. This would prove fatal very quickly if the body did not develop insulin resistance. The high levels of insulin would move blood glucose into the cells rapidly causing extremely low blood sugars or hypoglycemia. Untreated, hypoglycemia causes seizures and death. Homeostasis is the method the body uses to prevent death in this instance and develops insulin resistance quickly, keeping glucose levels in the blood stream within normal limits and preventing hypoglycemia (Fung, The Obesity Code: Unlocking the Secrets of Weight Loss).

How does insulin resistance happen? The opioid crisis is a good example to show how resistance happens in the body to protect and maintain homeostasis. When a person uses opioids, the opioids attach to opioid receptors to provide pain relief. Receptors that have constant stimuli from exposure to the opioid drugs respond by reducing the number of opioid receptors in the body. In order to achieve pain relief, the amount of opioids needed increases. This becomes a vicious cycle. The same cycle occurs with antibiotics which cause bacteria to develop resistance. Viruses, alive or dead, cause the body to build resistance to viruses, and this is why vaccines work to prevent diseases. The same thing happens with insulin. Insulin causes insulin resistance. Resistance is a protective mechanism (Fung, The Obesity Code: Unlocking the Secrets of Weight Loss).

In the 1960s, scientists reported that hormones regulate everything in body including fat tissue. Insulin is the primary hormone regulating blood glucose levels and fat. When there is excess insulin in the body, fat accumulates. When insulin levels fall, fat is burned for fuel. Obesity is ultimately a hormonal imbalance and not a caloric one (Taubes).

So if insulin makes a person fat and lack of insulin makes a person thin, what lifestyle changes are necessary to reduce the risk for T2D? Preventing the weight gain or reversing weight gain can reduce the risk for developing T2D. The Diabetes Prevention Program (DPP) was a study that spanned more than a decade and was sponsored by the National Institutes of Health (Center for Disease Control (CDC)). The study demonstrated that lifestyle changes resulting in weight loss of 7% or more reduced the incidence of developing T2D by 58%. Research was done by the American Diabetes Association (ADA) in the Look AHEAD study. This study supports the finding that weight loss is the single most important factor to reducing the progression of prediabetes to diabetes and to reducing the need for medications in patients already diagnosed with T2D (ADA). The Pre-Diabetes Risk Assessment, a self-assessment that the CDC recommends that Americans take yearly, ranks weight as the highest risk factor for the development of T2D (Center for Disease Control (CDC)).

Dr. Jason Fung is a kidney specialist or nephrologist in Toronto, Canada. Dr. Fung was discouraged because he saw patients with end stage renal disease (ESRD) after T2D had caused irreversible damage to their kidneys. Most patients who receive standardized T2D treatment of medication and insulin required more and more doses as time went on and their T2D continued to progress. He started looking for solutions to prevent the damage and found that T2D was reversed in more than 90% of the people who had gastric bypass surgery within six to 26 weeks after the procedure.

He started researching the cause for the reversal because he had been taught in medical school that T2D is a progressive, irreversible disease. He found that the gastric bypass surgery reduces the amount calories ingested in the body which lead to lower glucose levels and therefore lower insulin levels. By studying gastric bypass surgery patients, Fung connected the dots and discovered that high insulin levels were the force behind the development and progression of T2D.(Fung, Insulin Toxicity and How to Cure Type 2 Diabetes).

Gastric surgery can be done by cutting out a portion of the stomach or by putting a band around the stomach, making it difficult to overeat. Subjects have a very low calorie intake and blood glucose levels come down quickly. In fact, weight loss begins to accelerate once the blood glucose levels have normalized (Fung, Insulin Toxicity and How to Cure Type 2 Diabetes). Fung theorizes that fat is lost from the pancreas and liver before weight loss is seen. One study done at Newcastle University in Wales found that when subjects with T2D had gastric banding surgery they lost fat from the pancreas. The study found that losing less than one gram of fat from the pancreas restored insulin production in the subjects (Knapton).

To see if this could be replicated without the surgery, a study was done with subjects eating a gastric bypass diet. The subjects experienced the same outcome as the subjects who had gastric bypass surgery. The subjects lost fat in their liver and pancreas. The beta cells in the pancreas that produce insulin began normal function. The study demonstrated that T2D can be reversed with weight loss (Fung, Insulin Toxicity and How to Cure Type 2 Diabetes).

Research has shown that insulin leads to weight gain. Elevated blood glucose triggers the release of insulin. Dr. David Ludwig states that the fastest way to stabilize blood glucose and lower insulin levels is to reduce carbohydrate intake (Harvard TH Chan School of Public Health). All cells in the body use glucose. However, not all types of foods provoke the same insulin response from the pancreas. Eating high-glycemic processed carbohydrate will cause insulin levels spike which will cause hormone-sensitive lipase, an enzyme needed for the release of triglycerides from fat tissue, to be shut off. This results in more calories being stored in fat cells rather than in the blood, which leads the brain to think that the body is hungry and increasing appetite. On the other hand, foods like non-starchy vegetables, meats, and nuts take longer to digest, therefore blood sugar levels remain fairly low resulting in a moderate insulin response from the pancreas.

There are multiple ways to lose weight. Fung recommends a ketogenic diet - high fat, moderate protein, low carbohydrate - to reduce insulin release. For some of his patients he adds therapeutic fasting to their regimen. This involves eating very low calorie diets similar gastric bypass patients - surgery without the surgery. Fung recommends a fast that is at least 12 hours, and sleep hours count toward time fasting. For example, if a person stops eating at 8 p.m., the next meal would not occur before 8 a.m.

Ludwig explains that research supports that low carbohydrate diets are beneficial for many people. For people who need to lose weight to prevent T2D, very low carbohydrate diets including the ketogenic diet may be the long-term option. "In some cases, a very low carbohydrate diet can reverse diabetes rapidly, without severe calorie deprivation" (Harvard TH Chan School of Public Health). A diet that reduces the production of insulin leading to weight loss not only can reverse T2D, it can prevent T2D. In addition, cardio exercise such as walking has been shown to reduce insulin resistance. The DPP recommendation for lifestyle changes to reduce the risk for developing T2D is for people to engage in 150 minutes of exercise per week that raises the heart rate (Center for Disease Control (CDC)). Walking 30 minutes, five days of the week, will accomplish this goal.

Almost everybody who has access to the traditional diet of high refined carbohydrates has known someone or has experienced personally the effects of T2D. Like many individuals, they were probably told that their T2D was progressive and irreversible. To help manage their T2D they were most likely told by their health provider to begin a standardized treatment of medication that may include insulin. Although many scientists, researchers and doctors are coming to the conclusion that T2D can be improved and reversed with lifestyle changes, such as weight loss and exercise. To help reduce the risk for developing T2D people should be educated that overconsumption of processed carbohydrates and a sedentary lifestyle leads to the protective mechanism of insulin resistance. Insulin resistance causes an increase of the fat cells and eventually induces obesity, which is the primary risk factor for type 2 diabetes. Additional research is needed into prevention of T2D. Individual who decide to eat a diets that rich in unprocessed foods, healthy fats, and adequate protein while reducing added sugars and refined starchy foods may provide a model for future generations free from type 2 diabetes.

Rachel, are you writing this as a paper for your peers or a paper for lay people? The audience that will be reading this research should be the primary consideration of your opening statement. If this is a paper for fellow professionals, then the presentation is just fine. Although, I feel that a stronger introduction is required because, in a normal research paper, the first quote should not come until after the paragraph that explains the purpose and gives a simple definition of the illness as the basis of the upcoming discussions and reasoning.

This is a very well researched paper. However, I feel that it should open with the "How does insulin resistance happen?" because it reads like the actual definition, problem presentation, and thesis proposal in a highly accurate manner. Then this should be followed up by the story about Diabetesville because the story helps to illustrate the complicated explanation that the early part of the paper contains. In my point of view, this presentation will make the paper more engaging for both the regular people reading the paper and your peers. The rest of the paper, I believe, is very well researched and explained. It feels like I am reading a simple presentation during most instances, rather than a complicated and highly technical medical presentation. Your concluding statement is a strong finish to the paper and wraps up the discussion in an informed manner. I walked away from reading this paper more educated about T2D and IR.