Obesity Flashcards
obesity
condition of excess body weight. Clinical
definition is typically BMI ≥ 30 (kg/m2 )
Insulin sensitivity
response of peripheral tissue to a given concentration of insulin
Insulin resistance
decreased ability of insulin to adequatley signal to peripheral tissues
impaired glucose tolerance IGT
abnormally high increase in blood glucose after ingestion of carb
What 3 main tissues does insulin act on
AT liver and SKM
What are the metabolic effects of insulin in
each of these tissues?
draw it out
hyperglycaemia
f insulin cannot promote muscle (or adipose) glucose uptake + cannot turn off
liver glucose output = high blood glucose
IR
Hyperlipidemia
If insulin cannot turn off lipolysis = high blood fatty acids
IR
glucose homeostasis
draw it out slide 11
glucose control
ability to keep blood glucose levels within
normal healthy range over time
T2D
clinical condition characterized by
high blood glucose concentrations resulting from defects in
insulin action (i.e., insulin resistance), insulin secretion, or
both
pre-diabetes
high-risk state for developing T2D, characterized
by insulin resistance that leads to glucose levels that are
above normal but not yet in the diabetes range
stage 1
beta cells are still working and producing insulin high insulin and high glucose levels
stage 2
beta cells or pancreas in failing decrease in insulin high glucose levels
Hyperinsulinemic-euglycemic clamp
Infuse insulin at a constant/high rate to
achieve maximal physiological values
(insulin not limiting & “turn off” hepatic
glucose output)
* Infuse glucose at a variable rate to keep
blood glucose at ~5 mmol/L (i.e., normal
fasting levels)
– Requires frequent (every 5 minutes) blood
samples with rapid measurement of blood
glucose to adjust rate of infused glucose
* Greater rate of glucose infusion indicates
greater insulin sensitivity
– Tissues can take up more glucose with
insulin “clamped”
measuring IR
What tissue is primarily responsible for taking up glucose during a clamp
skeletal muscle
Fasting blood sample-derived
insulin resistance index
Fasting plasma glucose (FPG) combined with fasting plasma
insulin (FPI) primarily reflect liver (hepatic) insulin resistance.
i.e., how well insulin is working to inhibit liver glucose output
* High resistance (low sensitivity) = high fasting glucose
* Low resistance (high sensitivity) = normal fasting glucose
measuring IR
HOMA-IR
homeostasis model assessment of insulin resistance è
mathematical modeling based on tests of liver function where healthy humans
given infusions of insulin and glucose at various levels.
HOMA-IR = fasting glucose X fasting insulin / 22.5
oral glucose tolerance test
Consume glucose drink (75g) and measure blood
glucose (and insulin) at various intervals up to 2 hr
* Blood glucose response gives indication of ability
of tissues to “clear” glucose
– Skeletal muscle responsible for ~80% of glucose
uptake!
– Higher blood glucose response = impaired glucose
tolerance
* If insulin measured simultaneously can get
indication of insulin sensitivity
measuring glucose tolerance
Hemoglobin A1C
measuring glucose control
A1C represents the % of
hemoglobin (within red blood
cells) that have been
modified by addition of
glucose residues.
A1c value approximates your
average level of blood sugar
over the last 2-3 months
Continuous subcutaneous glucose
monitoring (CGM)
measuring glucose control
CGM provides detailed information on glucose fluctuations
under free-living conditions for up to 7 days
* Post-prandial glycemic excursions predict diabetic
complications (Ceriello et al. 2004; Aryangat & Gerich, 2010)
CGM average 24 hr
glucose is correlated with
A1C but may provide
additional information on
pattern of glucose control
diagnosing T2D and pre diabetes
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