Type 2 Diabetes Flashcards
What is the modern T2D diagnostic criteria?
- Fasting plasma glucose >=126mg/dl on two separate occasions
- Random glucose >200mg/dl with classic symptoms
- 2 hr postprandial glucose >=200mg/dl after consuming 75g carbs (ie oral glucose tolerance test)
- HbA1c>=6.5
What is HbA1c?
Reflects the average plasma glucose level over the past 2-3 mo. Non enzymatic glycosylation of Hb amnio acid residues
What is type 2 diabetes?
May range from predominantly insulin resistance with relative insulin deficiency to a predominantly secretory defect with insulin resistance. Result of multiple defects.
What is a major contributor to the dev of insulin resistance?
Obesity
When does progression to type 2 diabetes occur?
When B cells are no longer able to secrete sufficient insulin to overcome insulin resistance. Before that it is “prediabetes”
What two hormones regulate normal glucose homeostasis?
Insulin and glucagon
When is glucagon secreted
Fasting state, gluconeo and glycogenolysis–>inc blood glucose levels
What causes hyperglycemia?
Insulin resistance at the tissue level causes reduced glucose uptake into fat and muscle. This, in combo with excess glucose output by the liver, causes hyperglycemia
Inherited insulin resistant conditions are…
RARE
What environmental factors worsen insulin resistance?
- Smoking
- Aging
- Obesity
- In-activity
What is glucotoxicity
Toxic effect of sustained hyperglycemia that causes worsening of insulin resistance in skeletal muscle, liver, and also worsens secretory defects in the pancreas
What do high levels of free fatty acids do
Also increase insulin resistance
Why do beta cells fail?
More insulin resistance=more demand on beta cells=start to fail because can’t keep up with demand
Visceral fat
More associated with insulin sensitivity than ‘pear shape’
Describe the adipocyte dysfunction and ectopic lipid deposition model for insulin resistance
Overnutrition can overwhelm adipose ability to store fat and keep it from having toxic effects
XS free FAs travel in portal system and get despised in the liver and skeletal muscle where they interfere with insulin
Can’t store fat safely in adipose tissue..
What is the initial response to insulin resistance?
Hyperinsulinemia and islet hypertrophy
What is the long term response to insulin resistance?
There is a progressive decrease in pancreatic function, beta cells eventually fail, leading to diabetes
What types of toxicity induce beta cell dysfxn
Lipotoxicity and glucotoxicity
What is the sign of beta cell failure?
Loss of first phase insulin response (initial burst of insulin normally shuts down hepatic glucose production). This causes postmeal glucose to start rising
-In type II second phase must now deal with cab load and liver glucose that is pouring out
What is pre-diabetes?
HbA1c: =5.7%
Fasting glucose: =100mg/dl (impaired fasting glucose)
Oral glucose tolerance test (OGTT): =140mg/dl (impaired glucose tolerance)
What % US adults age 20+ have prediabetes
35%