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- What is insulin resistance?
Insulin resistance is defined as subnormal biological response to optimal con-
centration of insulin. In clinical practice, glucose lowering effect is often used
to define the biological response to insulin. However, the optimal concentration
of insulin required to produce normal biological response is variable as it
depends on age, gender, ethnicity, adipose tissue mass, and physical activity of
an individual. The clinical markers of insulin resistance include central obesity,
acanthosis nigricans, skin tags and double chin, and polycystic ovarian disease
in women (Fig. 12.8).- What are the causes of insulin resistance?
Insulin resistance may be classified as inherited or acquired. The genetic causes
of insulin resistance primarily include disorders associated with insulin recep-
tor mutation (leprechaunism, Rabson–Mendenhall syndrome, and type A insu-
lin resistance) or post-receptor signaling defect (lipodystrophies). The acquired
causes of insulin resistance include obesity, sedentary lifestyle, T2DM, endo-
crine disorders (Cushing’s syndrome, pheochromocytoma, PCOS), type B
insulin resistance (anti-insulin receptor antibody), and drugs (e.g.,
glucocorticoids).Fig 12.8 A young girl
with hyperandrogenism,
insulin resistance, and
acanthosis nigricans
(HAIRAN syndrome)
12 Diabetes in the Young