Page 1: Carbohydrates

• Primary source of energy for brain, erythrocytes, retinal cells

• Major food source and energy supply for the body

• Stored as Glycogen in the liver and muscle

• Diseases: Hyperglycemia and Hypoglycemia

• Carbohydrates are hydrates of aldehyde or ketone derivatives

Page 2: General description of carbohydrates

• Carbohydrates contain CHO (Carbon, Hydrogen, Oxygen)

• Classifications based on:

  • Number of carbons (Trioses, tetroses, pentoses, hexoses)

  • Properties (Size of the carbon, Location of the functional group, Number of sugar units, Stereochemistry of the compound)

Page 3: Classification of carbohydrates based on the number of sugar units

• Monosaccharides: Simple sugars with more than 3 carbons (e.g., glucose, fructose, galactose)

• Disaccharides: Two monosaccharides joined by Glycosidic linkages (e.g., maltose, sucrose, lactose)

• Oligosaccharides: Chaining of 2 to 10 sugar units

• Polysaccharides: Linkages of many monosaccharide units (e.g., starch and glycogen)

Page 5: Pathways in Glucose Metabolism

• Glycolysis: Metabolism of glucose to pyruvate/lactate for energy production

• Gluconeogenesis: Formation of glucose-6-phosphate (G6P) from non-carbohydrate sources

• Glycogenolysis: Breakdown of glycogen to glucose

• Glycogenesis: Conversion of glucose to glycogen

• Lipogenesis: Conversion of carbohydrates to fatty acids

• Lipolysis: Decomposition of fats

Page 7: INSULIN

• Hypoglycemic agent

• Hormone responsible for the entry of glucose into the cell

• Synthesized by the cells of the Islet of Langerhans

• Increases glycogenesis, lipogenesis, and glycolysis

• Inhibits glycogenolysis

Page 8: Glucagon

• Hyperglycemic agent

• Primary hormone responsible for increasing glucose levels

• Synthesized by the A cells of Islets of Langerhans

• Released during stress and fasting

• Promotes glycogenolysis and gluconeogenesis

Page 9: Hormones

• Epinephrine: Increases plasma glucose by inhibiting insulin, promotes glycogenolysis and lipolysis

• Cortisol: Increases plasma glucose by decreasing intestinal entry to the cell, increases gluconeogenesis and lipolysis

• Growth hormone: Increases glucose by decreasing entry of glucose into the cell, increases glycolysis

• ACTH: Conversion of glycogen to glucose, promoting gluconeogenesis

• Thyroxine: Increases plasma glucose, increasing glycogenolysis and gluconeogenesis

• Somatostatin: Inhibits insulin, glucagon, and growth hormone

Page 13: Conditions: HYPERGLYCEMIA

• Increase in plasma glucose

• Diabetes Mellitus: Metabolic disorder with a defect in insulin secretion or action

• Types: Type I, Type II, Other specific types, Gestational DM

Page 14: Laboratory findings in Hyperglycemia

• Increase in glucose in plasma and urine

• Increase in specific gravity

• Presence of ketones in serum and urine

• Decrease in blood and urine pH

• Electrolyte imbalance: Low sodium and bicarbonate, high potassium

Page 15: Type I Diabetes Mellitus

• Pancreatic islet B cell destruction

• Cellular-mediated autoimmune destruction of B cells, insulin secretion deficiency (insulinopenia)

• Onset in childhood or adolescence

• Initiated by environmental factors or infection

• Abrupt onset

• Insulin-dependent

• Ketosis prone

• Symptoms: Polydipsia, polyphagia, polyuria, weight loss, hyperventilation, mental confusion, loss of consciousness

• Complications: Nephropathy, neuropathy, retinopathy, heart disease

Page 17: Type II Diabetes Mellitus

• Due to insulin resistance with an insulin secretory defect

• Common in obese individuals

• Associated with age, obesity, and lack of exercise

Page 18: Other specific types of Diabetes Mellitus

• Genetic defects: Down syndrome, Klinefelter syndrome

• Pancreatic disease

• Drugs and Chemicals: Dilantin and pentamidine, Thiazides and glucocorticoid

• Maturity onset diabetes of youth: Rare form, inherited, autosomal dominant

Page 19: Gestational Diabetes Mellitus

• Recognized during pregnancy (24 to 28 weeks of gestation)

• Metabolic and hormonal changes

• Complications for the baby: Respiratory distress, hypocalcemia, hyperbilirubinemia

Page 20: Idiopathic Type I Diabetes and Impaired fasting glucose

• Idiopathic Type I Diabetes: No known etiology, strongly inherited

• Impaired fasting glucose: Intermediate stage between normal and diabetes level

Page 21: Risk factors for Diabetes Mellitus

• Glucosuria

• Age: 45 years old, FBG every 3 years

• BMI >25

• Risk factors: Physically inactive, family history, high-risk population, history of GDM (Gestational DM), hypertension, high HDL (high-density lipoprotein)

Page 27: Hypoglycemia

• Symptoms appear at 50 to 55 mg/dL

• Diagnostic hypoglycemia at <50 mg/dL

• Results from imbalance in glucose utilization and production

• Symptoms: Increased hunger, sweating, nausea, vomiting, dizziness, nervousness, shaking, blurring of speech and sight, mental confusion

Page 28: Diagnostic criteria for Diabetes Mellitus

• FPG (Fasting Plasma Glucose):

  • Pre-diabetes: <100 mg/dL

  • Impaired PG: 100-125 mg/dL

  • DM: >126 mg/dL

• OGTT (Oral Glucose Tolerance Test):

  • Non/Normal: <140 mg/dL

  • Impaired GTT: 140-199 mg/dL

  • DM: >200 mg/dL

Page 29: Diagnostic criteria for Gestational Diabetes Mellitus

• Age: >25 years old

• Overweight

• Family history

• History of abnormal glucose metabolism

• Glucosuria

• PCOS (Polycystic Ovary Syndrome)

• Ethnic group

Page 25: Impaired Fasting Glucose and Impaired Glucose Tolerance

• Impaired Fasting Glucose: Fasting Blood Glucose (FBG) between 100-126 mg/dL

• Impaired Glucose Tolerance: 2-hour Oral Glucose Tolerance Test (OGTT) between 140-199 mg/dL

Page 26: Diagnostic criteria for Gestational Diabetes Mellitus

• Fasting: >95 mg/dL

• 1 hour: >180 mg/dL

• 2 hours: >155 mg/dL