Carbohydrates

• Insulin is secreted by beta cells of the pancreas

  The mechanism of action (MOA) of insulin includes cellular uptake, glycolysis, glycogenesis, and lipogenesis.
• Glucagon is secreted by alpha cells of the pancreas.

  The mechanism of action (MOA) of glucagon includes gluconeogenesis and glycogenolysis.
• Somatostatin is secreted by delta cells of the pancreas.

  The mechanism of action (MOA) of somatostatin includes regulating insulin and glucagon.
• Cortisol is produced from the zona fasciculata of the adrenal cortex.

  The mechanism of action (MOA) of cortisol includes gluconeogenesis and lipolysis.
• Epinephrine is produced from the adrenal medulla.

  The mechanism of action (MOA) of epinephrine includes glycogenolysis and lipolysis.
• ACTH is produced from the anterior pituitary gland.

  The mechanism of action (MOA) of ACTH includes gluconeogenesis, glycogenolysis, and cortisol secretion.
• Growth Hormone is produced from the anterior pituitary gland.

  The mechanism of action (MOA) of growth hormone includes inhibiting cellular uptake and glycolysis.
• Thyroxine is produced from the thyroid gland.

  The mechanism of action (MOA) of thyroxine includes intestinal absorption of glucose, gluconeogenesis, and glycogenolysis.
• Random Plasma Glucose

  Normal: <200 mg/dL

  DM: ≥200 mg/dL with symptoms
• FPG

  Normal: <100 mg/dL

  Pre-diabetes: 100-125 mg/dL

  DM: ≥126 mg/dL
• 2-hour PG (OGTT)

  Normal: <140 mg/dL

  Pre-diabetes: 140-199 mg/dL

  DM: ≥200 mg/dL
• HbA1C

  Normal: <5.7%

  Pre-diabetes: 5.7 - 6.4%

  DM: ≥6.5%
• Standard Glucose Load for OGTT: 75g Glucose
• One-step Method for GDM

  Glucose load: 75g

  Diagnosis is made if any of the following is met

  FPG: ≥92 mg/dL

  1-hr PG: ≥180 mg/dL

  2-hr PG: ≥153 mg/dL
• Two-step Method

  Step 1 (O' Sullivan Test): 1-hr PG

  Glucose load: 50g

  • If the 1-hr PG is ≥130, 135, or 140 mg/dL proceed to step 2

  Step 2: 3-hr PG

  Glucose load: 100g

  Diagnosis is made if 2 or more criteria is met

  FPG: ≥95 mg/dL

  1 hr: ≥180 mg/dL

  2 hr: ≥155 mg/dL

  3 hr: ≥140 mg/dL
• Whole blood glucose is 10-15% lower than plasma glucose
• HBA1C or Glycated Hemoglobin

  • Provides an index of average blood glucose levels over the past 2-3 months
• Fructosamine

  Used to asses glycemic control over the past 2-3 weeks
• Half-life of Albumin: 17 days
• Microalbuminuria - Early indicator of diabetic nephropathy
• Rate of Glycolysis in normal serum

  • Room temperature: 7 mg/dL/hour
  • Ref temperature: 2 mg/dL/hour
• Copper Reduction Method

  • Most useful in testing galactosemia
• Glucose Oxidase - Specific for Beta-D-Glucose
• Mutarotase - Enzyme that converts alpha-glucose to beta-glucose
• Polarographic Glucose Oxidase - Measurement of the degree of oxygen consumption using a Clark electrode
• Hexokinase - Reference method for glucose determination

  Enzymes used: Hexokinase & G6PD

  Effect of hemolyzed or icteric sample: Falsely decreased
• Glucose Dehydrogenase - Specific for glucose; Used mainly in POCT Glucometers
• Folin-Wu: Phosphomolybdenum

  Nelson-Somogyi: Arsenomolybdenum

  Neocuproine: Cu-Neocuproine complex
• 10% Contamination of 5% dextrose can increase plasma glucose by 500 mg/dL
• Ia (Von Gierke): Glucose-6-phosphatase (G6P)
• II (Pompe): Lysosomal acid alpha glucosidase
• IIIa (Cori-Forbes): Glycogen debranching enzyme
• IV (Anderson): Glycogen branching enzyme
• V (McArdle): Phosphorylase
• VI (Hers): Glycogen phosphorylase
• VII (Tarui): Phosphofructokinase
• IXa: Phosporylase kinase
• XI (Fanconi-Bickel): Glucose transporter 2