What are normal insulin levels?
The exact values for normal or high insulin levels vary according to the laboratory and the type of test performed. With insulin resistance, there is a high fasting insulin level and a normal to high fasting blood glucose level. High or elevated insulin levels can be seen with other medical conditions as well, including insulin-producing tumors (insulinomas), Cushing syndrome, and fructose or galactose intolerance.
What medical conditions are associated with insulin resistance?
While the metabolic syndrome links insulin resistance with abdominal obesity, elevated cholesterol, and high blood pressure; several other medical other conditions are specifically associated with insulin resistance. Insulin resistance may contribute to the following conditions:
Type 2 Diabetes: Overt diabetes may be the first sign insulin resistance is present. Insulin resistance can be noted long before type 2 diabetes develops. Individuals reluctant or unable to see a health-care professional often seek medical attention when they have already developed type 2 diabetes and insulin resistance.
Fatty liver: Fatty liver is strongly associated with insulin resistance. Accumulation of fat in the liver is a manifestation of the disordered control of lipids that occurs with insulin resistance. Fatty liver associated with insulin resistance may be mild or severe. Newer evidence suggests fatty liver may even lead to cirrhosis of the liver and, possibly, liver cancer.
Arteriosclerosis: Arteriosclerosis (also known as atherosclerosis) is a process of progressive thickening and hardening of the walls of medium-sized and large arteries. Arteriosclerosis is responsible for:
Other risk factors for arteriosclerosis include:
- High levels of "bad" (LDL) cholesterol
- High blood pressure (hypertension)
- Diabetes mellitus from any cause
- Family history of arteriosclerosis
Skin Lesions: Skin lesions include increased skin tags and a condition called acanthosis nigerians (AN). Acanthosis nigricans is a darkening and thickening of the skin, especially in folds such as the neck, under the arms, and in the groin. This condition is directly related to the insulin resistance, though the exact mechanism is not clear.
- Acanthosis nigricans is a cosmetic condition strongly associated with insulin resistance in which the skin darkens and thickens in creased areas (for example, the neck, armpits, and groin).
- Skin tags occur more frequently in patients with insulin resistance. A skin tag is a common, benign condition where a bit of skin projects from the surrounding skin. Skin tags vary significantly in appearance. A skin tag may appear smooth or irregular, flesh-colored or darker than surrounding skin, and either be simply raised above surrounding skin or attached by a stalk (peduncle) so that it hangs from the skin.
Picture of skin tags on an adult armpit
Polycystic ovary syndrome (PCOS): Polycystic ovary syndrome is a common hormonal problem which affects menstruating women. It is associated with irregular periods or no periods at all (amenorrhea), obesity, and increased body hair in a male pattern of distribution (called hirsutism; for example, moustache, sideburns, beard, mid-chest, and central belly hair).
Hyperandrogenism: With PCOS, the ovaries can produce high levels of the hormone testosterone. This high testosterone level can be seen with insulin resistance and may play a role in causing PCOS. Why this association occurs is unclear, but it appears the insulin resistance somehow causes abnormal ovarian hormone production.
Growth abnormalities: High levels of circulating insulin can affect growth. While insulin's effects on glucose metabolism may be impaired, its effects on other mechanisms may remain intact (or at least less impaired). Insulin is an anabolic hormone which promotes growth. Patients may actually grow larger with a noticeable coarsening of features. Children with open growth plates in their bones may actually grow faster than their peers. However, neither children nor adults with insulin resistance become taller than predicted by their familial growth pattern. Indeed, most adults simply appear larger with coarser features. The increased incidence of skin tags mentioned earlier may occur through this mechanism too.
Reproductive abnormalities in women