My daughter is being treated by an endocrinologist for hypothyroidism. She has what looks like ‘dirty skin’ around her neck. The doctor said this is a sign of insulin intolerance and that she is borderline diabetic. What is insulin intolerance and is this ‘dirty skin’ look a symptom?

I suspect the “dirty skin” you’re seeing actually represents a skin condition called Acanthosis nigricans. This is a skin disorder present in association with endocrine diseases (i.e., diabetes, obesity, pituitary tumors, or Cushing’s disease). It is characterized by brown, velvety hyperkeratotic patches in the body folds. I also suspect that your physician used the term “insulin resistance” in describing why that velvety skin was present. Insulin resistance is:
A state in which a given level of serum insulin produces a less than expected biological effect. Patients may vary from normoglycemic to severely diabetic despite large doses of insulin. Many people with Type 2 diabetes produce enough insulin, but their bodies do not respond to the action of insulin. This may happen because the person is overweight and does not respond well to insulin. Also, as people age, their body cells lose some of the ability to respond to insulin. Insulin resistance is also linked to high blood pressure and high levels of fat in the blood (see Syndrome X).

Another kind of insulin resistance may rarely happen in people who take insulin injections. They may have to take very high doses of insulin every day (e.g., 200 units or more (in adults) to bring their blood glucose down to the normal range. This has also been called “insulin insensitivity.”

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