5 - Diabetes Mellitus Flashcards
What are the effects of insulin on glucose?
- decreases glucose output
- increases uptake of glucose by muscles
What are the effects of insulin on lipids?
- decreases lipolysis
- decreases ketogenesis
How does insulin decrease proteolysis?
- cortisol increases proteolysis when stressed
- insulin prevents amino acid oxidation in muscle cells
- insulin increases re-synthesis of proteins from amino acids
- amino acids could get into circulation and move to liver for glucose production
What is a ketone body and its function?
- 3 water soluble molecules produced by liver from fatty acids during low food intake
- acetone, acetoacetic acid and β-hydroxybutyric acid
- enter circulation and used by muscles
How is insulin deficiency identified?
- high blood glucose
- high ketone bodies
Which hormones inhibit and stimulate gluconeogenesis?
- inhibit: insulin
- stimulate: somatotrophin, cortisol, catecholamines and glucagon
What are the features of gluconeogenesis in the liver?
- gluconeogenic amino acids enter liver by specific transporter channels
- glucagon increases uptake of amino acids by liver
- protein synthesis stimulated by liver
- amino acids used to make glucose in gluconeogenesis
- glucose from gluconeogenesis enters circulation as hepatic glucose output (HGO)
What are the effects of insulin on adipocytes?
- triglycerides from vasculature too big to directly enter adipocytes
- lipoprotein lipase breaks down triglycerides into glycerol and fatty acids so can be absorbed by adipocytes
- insulin stimulates lipoprotein lipase
- glucose entering adipocyte used to make NEFA or chopped to make 2 glycerols (fatty acids stuck on to make triglycerides)
- insulin stops lipolysis
What are the features of glucose transporter 4 (GLUT-4)?
- glucose mainly taken up by GLUT-4
- abundant in muscle and adipose tissue
- insulin stimulates GLUT-4
- hydrophobic elements on outside embedded into membrane
- hydrophilic core allows glucose into cell
- sits in vesicles in cytoplasm (insulin recruits them to membrane)
- stress hormone inhibits uptake of glucose by GLUT-4
What are features of the fasted state?
- low insulin:glycogen ratio
- normal blood glucose concentration due to change in insulin ratio
- glucagon ratio maintains normal blood glucose conc.
- muscle uses lipids
brain uses glucose then ketone bodies - increase in NEFA concentration, proteolysis, lipolysis and HPO
- decrease in amino acid concentration
What are features of the fed state?
- high insulin:glucagon ratio
- stored insulin released and then 2nd phase insulin released
- stops HPO
- increases glycogen, protein synthesis and lipogenesis
- decreases gluconeogenesis and proteolysis
What are the features of insulin resistance?
- hypertension
- high triglyceride
- low HDL
- high LDL
- fasting blood glucose > 6mmol/l
- adipocytokines
- inflammatory state
- energy expenditure
- high omental fat (large waist circumference)
What are the features of insulin resistance?
- resides in liver, muscle and adipose tissue
- insulin and receptor normal but post-receptor effect not the same
- increase in LDL (dyslipidaemia)
What are the features of dyslipidaemia?
- major cause of heart disease in people with diabetes
- causes damage to blood vessels leading to heart attacks
How is type 2 diabetes mellitus managed through the diet?
- control calorie intake
- reduce fat, refined carbohydrate and sodium (lower hypertension risk)
- increase complex carbohydrate and soluble fibre
