Peripheral Obesity: SubQ fat; excess below the waist; not a major health risk factor"
Central (Abdominal) Obesity: Excess visceral fat around stomach & waist; very strong
indicator of health risk! "
-visceral fat is best quantiﬁed by MRI, CT scans, but $$$"
-waist circumference = easiest clinical measure to predict visceral fat stores"
-independent predictor of all-cause mortality in men"
-associated with insulin resistance"
•a consequence of defects in insulin signalling that leads to impaired GLUT4
translocation to the membrane"
•leads to reduced insulin-stimulated glucose uptake into skeletal muscle"
Insulin Resistance & Type II Diabetes
-Fasting hyperglycaemia: >7 mM (indicative of type II diabetes)"
-Increased, normal or low [ ] of insulin — depending on stage of development"
-Insulin resistance & type II diabetes can be assessed by:"
•Oral Glucose Tolerance Test (OGTT)"
•Euglycemic/Hyperinsulinemic Clamp "
-measures acute metabolic response to glucose ingesting at the whole body level "
-Method: 75g oral glucose test"
-Diagnostic Criteria at2 hours after the drink:"
7.8 mM = impaired glucose tolerance 11.1 mM = type II diabetes "
‣However, with this test, both lean and obese
individuals respond in the same way! The
glucose data looks pretty good and are not in
the range of impaired glucose tolerance or type
‣This test is done clinically and often only
glucose is measured - the doctor has no idea
that the insulin response levels are much
greater (compared to a lean individual) in order
to have a similar glucose curve"
•the pancreas secretes a lot of insulin into the
blood and are nowhere close to returning to
baseline at the end of the test"
Hyperinsulinemic Euglycemic Clamp
-the “gold standard” to measure whole body
insulin sensitivity; measures responsiveness to
insulin but used in research ($$$)"