What would be the effect on blood sugar if insulin receptors stopped working?

If insulin receptors stopped working, it would have several effects on blood sugar levels:

1. Hyperglycemia: Insulin is a hormone that helps regulate blood sugar levels by allowing glucose to enter cells for energy. Without functional insulin receptors, cells would not be able to take up glucose from the bloodstream, leading to a buildup of glucose in the blood, resulting in hyperglycemia.

2. Impaired Glucose Uptake: Insulin receptors are critical for the transport of glucose into various tissues, particularly muscle, liver, and adipose tissue. Without functional insulin receptors, these tissues would not be able to effectively take up glucose from the blood, leading to reduced glucose utilization and increased blood sugar levels.

3. Reduced Glucose Storage: Insulin also promotes the storage of glucose in the form of glycogen in the liver and muscles. Without functional insulin receptors, the ability of these tissues to store glucose would be impaired, contributing to elevated blood sugar levels.

4. Increased Gluconeogenesis: In response to insulin resistance or deficiency, the body may increase the production of glucose by a process called gluconeogenesis, primarily in the liver. This process converts non-carbohydrate substances into glucose, further contributing to higher blood sugar levels.

5. Ketoacidosis: In severe cases, the inability to utilize glucose for energy can lead to a buildup of ketones in the bloodstream, a condition known as ketoacidosis. This is especially common in people with type 1 diabetes where there is an absolute lack of insulin.

Therefore, if insulin receptors stopped working, the overall effect would be an impaired ability of cells to take up and utilize glucose, resulting in elevated blood sugar levels and potentially leading to serious complications such as hyperglycemia, ketoacidosis, and long-term damage to various tissues.