Nutritional Aspects of DM

Question 1

describe why weight loss is seen in patients with T1D

Answer 1

• accelerated lipolysis and muscle proteolysis
  
  • insulin facilitates storage of triacylglycerol in adipose tissue. insulin deficiency = lipolysis
  • insulin facilitates entry of AAs into muscle and increases protein synthesis. insulin deficient = muscle proteolysis and negative nitrogen balance

Question 2

describe basis of glycosuria and polyuria

Answer 2

• hyperglycemia = more glucose being filtered through to kidney
• large amount of glucose filtered that exceeds the reabsorptive capacity of tubule; glucose is osmotically active which results in polyuria

Question 3

describe T2D

Answer 3

• target tissues for insulin (liver, adipose, muscle) do not respond to circulating insulin (insulin resistance) and there is a decrease in insulin secretion with time (B-cell fatigue)
  *

Question 4

describe the mechanism of insulin resistance

Answer 4

• reduced serum levels of adiponectin impair metabolism of fats
• elevated levels of leptin impairs insulin action
• elevated cirucling FFAs
  
  • high FFAs impair action of insulin on the liver and impair insulin secretion from pancreas
• low levels of glucagon-like peptide 1 (GLP-1) that increases insulin secretion

Question 5

describe normal action of insulin on blood glucose

Answer 5

1. insulin decreases hepatic glucose output
2. insulin increases the uptake of glucose by adipose tissue and skeletal muscle via GLUT-4
3. as a result of combined action on liver and extrahepatic tissues, insulin reduces the blood glucose level

Question 6

describe mechanism of hyperglycemia in T1 and T2 diabetes

Answer 6

• increased glucose production by liver
• decreased number of GLUT-4 in peripheral tissues
• decreased secretion of insulin from the pancreas

Question 7

describe diabetes flowchart

Answer 7

Question 8

describe dyslipidemia

Answer 8

• increased LDL
• decreased HDL
• increased serum triacylglycerol (increased VLDL) and reduced activity of lipoprotein lipase (insulin needed for optimal LPL activity)
• increased circulating FFAs due to increased breakdown of TAGs in adipose tissue

Question 9

describe laboratory tests for diagnosis of DM

Answer 9

• fasting plasma glucose >126 mg/dL
• oral glucose tolerance test (OGTT)
  
  • used to evaluate ability to regulate glucose metabolism
  • used to identify patients with prediabetes and gestational diabetes
  • 2 hour plasma glucose >200 mg/dL after 75 gms of glucose

Question 10

significance of HbA1c?

Answer 10

• HbA1c is the non-enzymatic glycation of hemoglobin
• indicator of long term glucose levels (past 3-4 months)
• HbA1c levels greater than 6.5% diagnostic for DM

Question 11

describe OGTT

Answer 11

• performed on an individual after an overnight fast
• subject administered a known load of glucose (75 gm)
• a diabetic patient has a high fasting glucose, high 2 hours glucose and a decreased tolerance to glucose

blue = normal

green = prediabetes

red = diabetic

Question 12

describe dietary modifications with carbohydrates

Answer 12

• foods that rapidly increase plasma glucose (high glycemia indexi) should be replaced with foods with lower glycemic index
• refined carbs (mono and disaccharide) content in the diet should be reduced and replaced by artificial sweeteners (aspartame, sugar alcohols)

Question 13

describe dietary lipids and dietary fiber modifications

Answer 13

• lipids:
  
  • low saturated fats
  • no trans fats
  • reduction in dietary cholesterol
  • Mediterranean diet (monounsaturated fatty acids)
  • increase omega-3
• increase dietary fiber content