Insulin Resistance

Insulin resistance is an increasingly common and very important risk factor for type 2 diabetes.

Insulin resistance occurs when the cells of the body, specifically the muscle, liver and fat cells, stop responding properly to insulin. This leads to glucose remaining in the bloodstream instead of being absorbed for energy and storage.

Over time these elevated blood glucose levels often lead to prediabetes, metabolic syndrome and type 2 diabetes. This is the result of the insulin-producing beta cells in the pancreas becoming overwhelmed by the body’s need for more insulin, itself a result of the diminished “insulin sensitivity” of the aforementioned muscle, liver and fat cells. Not enough insulin and glucose absorption to maintain glucose homeostasis translates to diabetes, and if not properly managed, serious diabetes complications like cardiovascular disease.

While prediabetes and diabetes can be diagnosed by measuring fasting glucose levels in the blood and the A1C test, insulin resistance has no such accessible test to this point. It can be diagnosed through measuring insulin levels in the blood (a test called the euglycemic clamp), but this is an expensive and rarely available clinical tool. Typically diagnosis of insulin resistance accompanies a diagnosis of prediabetes or metabolic syndrome, which is not ideal since insulin resistance often occurs first, but these conditions are all very closely linked.

The specific mechanisms that cause insulin resistance are still hot topics for research, but people that are overweight and obese are known to have a much higher likelihood of developing insulin resistance. This is possibly due at least in part to “chronic low-grade inflammation.” Some recent research is also suggesting that many people with insulin resistance have added difficulty in losing weight, so it is a potentially dangerous two-way street that is important to never go down in the first place.

Smoking, sleeping problems, and stress may also increase risk of insulin resistance, and are themselves major modifiable risk factors for type 2 diabetes. Genetics, pre-existing medical conditions and certain medications may also increase the risk of developing insulin resistance.

People that are inactive put themselves at substantially increased risk of insulin resistance and eventual diabetes. The physiological reason for this is that physical activity leads to the use of stored glucose for energy, requiring cells to absorb more glucose from the blood and maintaining healthy blood glucose levels. Muscle cells also require more energy, so for fit individuals with good muscle-to-fat ratios, glucose is naturally absorbed from the bloodstream at a greater rate than unfit individuals without the need for extra insulin production. Furthermore, research is demonstrating that regular physical activity actually increases the insulin sensitivity of muscle cells, in effect preventing or reversing insulin resistance. Being sedentary, on the other hand, eliminates all of these potential benefits for glucose metabolism and prolonged sitting itself may be an independent risk factor for type 2 diabetes.

Eating diverse and healthful diets of whole and fresh foods also is important in preventing insulin resistance, and reversing the condition before it leads to diabetes. This is best accomplished by eating dark leafy green vegetables, whole grains and many fresh fruits. These foods are typically high in fiber, micronutrients and phytonutrients, and also have low glycemic indices, which means the body slowly digests and absorbs essential nutrients while avoiding spikes in blood glucose levels. Therefore, less of a strain is put on the beta cells of the pancreas to produce enough insulin, and on cells in the body to absorb vast amounts of glucose at one time.

So like with so many topics related to type 2 diabetes, insulin resistance can be avoided, and reversed, through living healthfully and mindfully.

Resources and Further Reading

A solid and standard resource about insulin resistance: 
https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance

A study showing that daily physical exercise increases insulin sensitivity: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2551669/

A study showing that it is best to combine exercise and dietary changes to reduce weight and improve insulin sensitivity: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625541/

The firm connection between obesity and insulin resistance, and the specific mechanisms that explain this cause-and-effect, namely “visceral” fat buildup: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4038351/

A comprehensive analysis about insulin resistance and its connection to type 2 diabetes: 
http://diabetes.diabetesjournals.org/content/61/4/778

While insulin resistance is most commonly associated with type 2 diabetes, type 1 diabetics can also have insulin resistance, which is a dangerous circumstance known as “double diabetes”(link): 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671104/

Potentially dangerous cycle, insulin resistance also can lead to more weight gain: 
http://www.pre-diabetes.com/prediabetes/why-does-insulin-resistance-cause-weight-gain.html

The possible use of medications in improving insulin sensitivity in order to prevent or treat type 2 diabetes: 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3936017/