Insulin and controlling blood glucose Flashcards
Describe insulin and its role in metabolism
Physiologic role is nutrient metabolism
Made in pancreatic B-cells as pro-insulin
What is insulin’s mechanism of action?
Interacts with insulin receptors on cell membranes associated with tyrosine kinase.
Activation then leads to phosphorylation and activation og GTP binding proteins
Finally get transcription factors to be stimulated, affecting gene regulation
See metabolic effects with increasing glucose transport and glycogen synthetase
In diabetes mellitus, what is the difference between an absolute lack of insulin and just a lack of insulin?
Lack of insulin, is just that, not enough insulin
Absolute lack of insulin is the lack of beta cells
Describe type 1 Diabetes
Insulin dependent diabetes mellitus; apparent lack of insulin/decreased insulin sensitivity
Unrelated to diet/exercise.
Treated with insulin for a life time
Describe type 2 Diabetes
Non-insulin dependent diabetes mellitus
Treated with oral agents and possibly can resolve with diet/exercise
Can you inject human insulin?
Yes, cannot be absorbed and must be injected
What is the difference between the insulin preparations?
Duration of action
What are the insulin preparations?
Regular insulin - Humulin/Humalog - Short acting
Isophane insulin suspension - Humulin N/Novolin N; intermediate (18-24 hours)
Insulin glargine - Lantus
What are some toxicites with insulin and insulin preparations?
Hypoglycemia/Insulin Shock
CV symptoms - tachycardia, pallor, sweating
CNS symptoms - Tremor, nervousness, unrest, convulsions
Coma/death if not treated with glucose
Allergic hypersensitivity
Insulin resistance (but rare with use of human insulin)
Oral agents for controlling blood glucose require the patient to have something to work
Working beta cells
Is it type 1 or type 2 diabetes that tends to develop at 35?
Type 2; probably due to decreased sensitivity for insulin receptors/decreased efficiency of signal transduction of insulin-receptor complexes
People with type 2 diabetes can control their glucose through diet and exercise, true or false?
True
What is the general method of action for oral hypoglycemics?
Work to increase release of insulin from any remaining active beta cells instead of being an insulin replacement
Describe the sulfonylurea drugs
Bind to ATP dependent K channel to decrease K efflux, increase Ca++ influx, causing greater insulin upon stimulated release
Also cause increased sensitivity in peripheral tissues to insulin, more glucose uptake
Name the first and second generation sulfonylurea drugs
Tolbutamide (Orinase) Second generation: Glipizide (Glucotrol) Glyburide (Micronase) Glimepiride (Ammaryl)
What are toxicities of sulfoonyrea drugs?
Profound hypoglycemia possible Nausea Rash Blood disorders Jaundice Muscle weakness and ataxia Dizziness and mental confusion Allergic sensitivity to sulfa drugs
How do secretagogues work?
Like sulfonyruleas, stimulating insulin from functioning beta cells.
Describe secretagogues drugs
Short duration of action, use pre-prandial before eating
Can cause hypoglycemia (less than sulfyonureleas), nausea, dyspepsia, diarrhea
Describe sulfa interactions with secretagogue drugs
Not possible
Name the secretagogue drugs
Repaglinide (Prandin)
Nateglinide (Starlix)
What drug classifications are considered to be antihyperglycemic?
Biguanides Alpha-glucosidase inhibitors Thiazolidinediones "Incretin mimicking" "Gliptins"
What drug is considered to be an oral biguanide?
Metformin (Glucophage)
Describe the method of action for metformin
May decrease glucose output from liver (gluconeogenesis), increasing insulin action on muscle and fat to uptake into cell.
What is the major toxicity seen with metformin?
Significant increase in lactic acidosis, can be fatal in those with renal insufficiency
Rarely see megaloblastic anemia
Commonly see diarrhea, nausea or other GIT symptoms
