Insulin resistance syndrome is defined as a reduced response of cells of the human body to the hormone insulin. Above all, the muscles, liver and fat tissue are less sensitive to the hormone insulin.
The concept of insulin resistance has been around since the 1960’s. It was felt that the pancreas could distribute up to 200 units of insulin and was defined as “severe insulin resistance,” an insulin requirement of more than 200 IU over several days to reach normal blood glucose levels. Although it is now clear that a normal physiological insulin production is from 20 to 40 units, this old definition is further considered appropriate to differentiate so that patients with severe, unusual insulin have no resistance problems. Since 1985, the term has a broader scope and refers to a reduced response of cells of the human or animal body to insulin.
Insulin resistance during the day is highest in the early morning. There is often late in the afternoon a second, less high increase in insulin resistance.
Insulin resistance is the main cause of type 2 diabetes. The exact mechanisms that lead to insulin resistance in humans are currently poorly understood, but are under intense research. In this context, and in addition to polygenic predisposition, a number of secondary environmental factors are discussed. These include obesity, metabolic factors, age and lack of physical activity.
Not all scientists see the influence of carbohydrate-rich foods with a high glycemic index as a factor. The insulin resistance of type 2 diabetic patients is caused primarily by obesity and physical inactivity. Genetic factors are also a cause. In people the same age, same sex, same body weight and size, with the same caloric intake and physical activity, they can still have a different effect of insulin on the target cells. These differences are probably due to hereditary factors. Insulin resistance may also be increased by drugs. Infectious diseases may increase insulin resistance.
Mechanisms of insulin resistance
Insulin resistancy is increased by reducing the number of receptors with permanently elevated levels of insulin by IgG antibodies, which inhibit the biological activity of the insulin increased by enzymatic cleavage of insulin and decreased binding of insulin to its receptors. There are proteins: Tumour necrosis factor alpha (TNF-alpha); Plasminogen activator inhibitor I (PAI-1) and Resistin.
Determine the insulin resistance
A first indication of the presence of insulin resistance is the body weight. In all obese diabetics insulin resistance is assumed. It is now thought that especially the fat in the abdominal area distributes more substances which promote and strengthen resistance to insulin.
Waist circumference is a measure of supposedly dangerous abdominal fat, and body mass index (BMI), which has starting values of 27 kg/m2, together with an indication of familial predisposition to insulin tolerance. Furthermore, the blood lipid level (triglyceride levels above 2.44 mmol / l or can 215 mg / dL can be an indication of insulin resistance.
In the production of insulin, the pancreas is first a precursor molecule – the so-called proinsulin and is synthesized. This is again split. It then creates the actual hormone insulin, and an ineffective waste product, the C-peptide. In the context of insulin resistance there is more and more insulin, while disproportionately makes a lot of proinsulin. The latter is split into insufficient insulin and can be higher than that which is detected in the blood.
The insulin resistance in type 2 diabetics is best broken up by a strong reduction in caloric intake and by increasing physical activity. Even a short-term increase in insulin delivery to very high doses is needed in order to force a normnahe glycemic control, breaking through after a few days and insulin resistance, as seen by the much lower dose of insulin is necessary after the treatment. Insulin resistance may also be reduced by drugs: Acarbose; Metformin; Insulin sensitizers such as pioglitazone; Omega-3 fatty acids; ACE inhibitors and Rimonabant.
Insulin resistance and other diseases
Metabolic syndrome is closely associated with insulin resistance, because both diseases have the same origin. Furthermore, Type-2 diabetes, which develops from insulin resistance, is a risk factor for the emergence of the metabolic syndrome. Coming to obesity, when two other risk factors – diabetes, lipid disorders and hypertension are added, it is called metabolic syndrome. The metabolic syndrome is the main cause of heart attacks and strokes – the number 1 cause of death in The UK.