Insulin resistance is the condition in which normal amounts of insulin are inadequate to produce a normal insulin response from fat, muscle and liver cells. Insulin resistance (IR) in fat cells reduces the effects of insulin and results in elevated hydrolysis of stored triglycerides in the absence of measures which either increase insulin sensitivity or which provide additional insulin. Increased mobilization of stored lipids in these cells elevates free fatty acids in the blood plasma. Insulin resistance in muscle cells reduces glucose uptake (and so local storage of glucose as glycogen), whereas insulin resistance in liver cells reduces storage of glycogen, making it unavailable for release into the blood when blood insulin levels fall (normally only when blood glucose levels are low). Both cause elevated blood glucose levels. High plasma levels of insulin and glucose due to insulin resistance often lead to metabolic syndrome and type 2 diabetes, including its complications.

Symptoms of IR

1. Fatigue.
2. Brain fogginess and inability to focus. Sometimes the fatigue is physical, but often it is mental.
3. Low blood sugar. Mild, brief periods of low blood sugar are normal during the day, especially if meals are not eaten on a regular schedule; they are normally raised by mobilization of glucose into the blood from stored glycogen made from blood glucose previously taken by liver cells. But prolonged hypoglycemia, with some of the symptoms listed here, especially physical and mental fatigue, is not normal. Feeling agitated, jittery, moody, nauseous, or having a headache is common in insulin resistance, commonly with rapid relief once food is eaten.
4. Intestinal bloating. Most intestinal gas is produced from carbohydrates in the diet. Insulin resistance sufferers who eat carbohydrates sometimes suffer from gas.
5. Sleepiness. Many people with insulin resistance get sleepy immediately after eating a meal containing more than 20% or 30% carbohydrates.
6. Weight gain, fat storage, difficulty losing weight. For most people, too much weight is too much fat. The fat in IR is generally stored in and around abdominal organs in both males and females. It is currently suspected that hormonal effects from such fat are a precipitating cause of insulin resistance.
7. Increased blood triglyceride levels.
8. Increased blood pressure. Many people with hypertension are either diabetic or pre-diabetic and have elevated insulin levels due to insulin resistance. One of insulin's effects is on arterial walls throughout the body.
9. Depression. Because of the deranged metabolism resulting from insulin resistance, psychological effects are not uncommon. Depression is said to be the prevalent psychological symptom.

   Pathophysiology

   In a person with normal metabolism, insulin is released from the beta (β) cells of the Islets of Langerhans located in the pancreas after eating ("postprandial"), and it signals insulin-sensitive tissues in the body (e.g., muscle, adipose) to absorb glucose to lower blood glucose. The beta cells reduce their insulin output as blood glucose levels fall, with the result that blood glucose is maintained at approximately 5 mmol/L (mM) (90 mg/dL). In an insulin-resistant person, normal levels of insulin do not have the same effect on muscle and adipose cells, with the result that glucose levels stay higher than normal. To compensate for this, the pancreas in an insulin-resistant individual is stimulated to release more insulin. The elevated insulin levels have additional effects (see insulin) which further cause biological effects throughout the body.