Insulin resistance

Insulin resistance (IR) is a physiological condition in which cells fail to respond to the normal actions of the hormone insulin. The body produces insulin, but the cells in the body become resistant to insulin and are unable to use it effectively, leading to hyperglycemia. Beta cells in the pancreas subsequently increase their production of insulin, further contributing to hyperinsulinemia. This often remains undetected and can contribute to a diagnosis of Type 2 Diabetes.

Causation of type 2 diabetes

Explanation

• Insulin is a hormone that helps regulate the delivery of glucose into cells, providing them with energy.
• When cells become resistant to insulin, they are unable to take in glucose, amino acids, and fatty acids, causing these substances to 'leak' out of the cells.
• This can lead to a decrease in the insulin/glucagon ratio, which in turn decreases energy production and may cause an increase in blood glucose levels.
• Some cells, such as fat and muscle cells, require insulin in order to absorb glucose.
• When these cells do not respond adequately to insulin, blood glucose levels rise.
• The liver helps regulate glucose levels by decreasing its production of glucose in the presence of insulin.
• However, in people with insulin resistance, this normal reduction in liver glucose production may not occur.

In muscle and fat cells

• Insulin resistance in muscle and fat cells reduces glucose uptake and storage as glycogen and triglycerides, respectively.
• In liver cells, insulin resistance results in reduced glycogen synthesis and storage, as well as a failure to suppress glucose production and release into the blood. Insulin resistance often refers to reduced glucose-lowering effects of insulin, but it can also affect other functions of insulin, such as its effects on lipids in fat cells.
• Insulin resistance in fat cells reduces the normal uptake of circulating lipids and increases the hydrolysis of stored triglycerides, leading to increased mobilization of stored lipids and elevated levels of free fatty acids in the blood plasma.
• High levels of insulin and glucose due to insulin resistance are a major component of the metabolic syndrome.
• If insulin resistance is not compensated for by an increase in insulin secretion by the pancreas, blood glucose concentrations can increase and lead to the development of type 2 diabetes.

Causes of Insulin Resistance

Insulin resistance can be caused by genetic predisposition, obesity, lack of exercise, aging, and certain medications. It is often associated with metabolic disorders such as Type 2 Diabetes, obesity, and metabolic syndrome.

Effects of Insulin Resistance

When the body becomes resistant to insulin, beta cells in the pancreas increase their production of insulin to maintain normal blood glucose levels. This leads to hyperinsulinemia, or high levels of insulin in the blood. Over time, the increased demand for insulin production can lead to beta cell dysfunction and eventual beta cell failure, further contributing to the development of Type 2 Diabetes. It also causes darker, thicker, and velvety areas on the skin called acanthosis nigricans, especially on the neck, underarms, groin, and face.

Acanthosis nigricans of the neck

Insulin resistance can also lead to other health problems, including an increased risk of cardiovascular disease, fatty liver disease, and polycystic ovary syndrome (PCOS).

Diagnosis of Insulin Resistance

Insulin resistance is often diagnosed through blood tests, including a fasting blood glucose test, an oral glucose tolerance test, and a hemoglobin A1C test. These tests can indicate the level of insulin resistance and the likelihood of developing Type 2 Diabetes.

Treatment and Prevention of Insulin Resistance

Treatment and prevention of insulin resistance involve lifestyle modifications such as regular exercise, weight loss, and a healthy diet low in processed sugars and carbohydrates. In some cases, medications such as metformin or thiazolidinediones may be prescribed to improve insulin sensitivity and control blood glucose levels.

External links

• W8MD's article on Insulin resistance

See also

• Chronic Somogyi rebound
• Hyperinsulinemia
• Resistin
• Chronic stress
• Systemic inflammation
• Circadian rhythm disruption
• Advanced glycation end-products

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References

• Taylor, R., & Zimmet, P. (2010). Insulin resistance and Type 2 Diabetes. Lancet, 375(9733), 2252-2253.
• DeFronzo, R. A., Ferrannini, E. (1991). Insulin Resistance: A Multifaceted Syndrome Responsible for NIDDM, Obesity, Hypertension, Dyslipidemia, and Atherosclerotic Cardiovascular Disease. Diabetes Care, 14(3), 173-194.
• National Institute of Diabetes and Digestive and Kidney Diseases. (2020). Insulin Resistance and Prediabetes. Retrieved from [1]
• American Diabetes Association. (2021). Standards of Medical Care in Diabetes. Diabetes Care, 44(Supplement_1), S1-S232.