Glucose Flashcards
Hyperglycemia
Blood glucose concentration above upper end of reference range (although typically > 200)
Hypoglycemia
- Blood glucose concentration below lower end of reference range (although typically < 60)
- due to insulin producing tumor, medications, etc.
Glycolysis
Process that breaks down glucose to pyruvate for the eventual production of energy
Glycogenesis
Formation of glycogen (storage form of glucose)
Glycogenolysis
Breakdown of glycogen for the release of glucose
Gluconeogenesis
Formation of glucose from non-carbohydrate sources (i.e., amino acids, triglycerides)
Polysaccharides, Disaccharides, Monosaccharides
carbohydrates
poly = > 10 sugar units
di = 2 sugar units
mono = single sugar
Ketoacidosis
acidic state of the body due to increased ketones (from the utilization of fats instead of glucose as an energy source)
Ketonemia
when ketones are found in the blood
Ketonuria
when ketones are found in the urine
Oral Glucose Tolerance Test (OGTT)
test used to help diagnose diabetes
Gestational Diabetes Milletus (GDM)
secondary diabetes that can be seen in pregnancy
3 monosaccharides utilized in the body
Glucose, galactose, fructose
3 disaccharides utilized in the body
sucrose, maltose, lactose
Lactose composition
glucose + galactose
Maltose composition
glucose + glucose
Sucrose composition
glucose + fructose
Polysaccharide storage
stored as glycogen or starch
Metabolism of carbohydrates
Broken down in the mouth by salivary amylase
Denatured in the stomach by acid
Disacchridases break down disaccharides in the intestine and monosaccharides are absorbed
Glucose is processed in the liver and is stored in fat cells or is sent to be utilized by other cells
Major hormones controlling glucose blood levels
insulin and glucagon
Pathways for G-6-P
Embden-Myerhof pathway for glycolysis
Hexose Monophosphate pathway
Converted to glycogen
Insulin action
decreases blood glucose (glucose enters cells)
hypoglycemic agent
Glucagon action
increases blood glucose (glycogenolysis, gluconeogenesis)
hyperglycemic agent
Minor hormones controlling glucose
Epinephrine, cortisol (adrenal hormones)
Growth hormone, ACTH (pituitary hormones)
Thyroxine
Somatostatin
Epinephrine action
increases blood glucose concentration through glycogenolysis, gluconeogenesis, etc.
Cortisol action
increases blood glucose concentration through primarily gluconeogenesis using amino acids
Growth hormone action
increases blood glucose concentration
ACTH action
increases blood glucose concentration by stimulating cortisol release
Thyroxine (T4) action
increases blood glucose concentration by increasing metabolic rate (faster protein turnover, more gluconeogenesis, increased glucose absorption in GI tract)
Somatostatin (IGF) action
influences growth hormone
Type I Diabetes
- insulin-dependent diabetes mellitus
- insulin deficiency
- autoimmune destruction of beta islet cells
- usually young people
Type I Diabetes Chronic problems
- retinopathy (optic nerve susceptible to excess glucose)
- renal disease and nephropathy
- peripheral neuropathy
Type I Diabetes Lab Testing
Fasting glucose Urine specific gravity (increases with more glucose) Serum and urine osmolalities Ketones Blood and urine pH Electrolyte imbalance
Type II Diabetes
- non-insulin dependent diabetes mellitus
- many are obese
- 90% of diabetes cases are Type II
- lack adequate insulin receptors or adequate insulin synthesis
- treatment can lead to hypoglycemia
Secondary Diabetes
- diabetic state due to condition/disease
- gestational diabetes
- cancer of the pancreas (dec. insulin), pancreatitis
- hemochromatosis
- Cushings syndrome (inc. cortisol), acromegaly (inc. GH)
Glucose methods
Glucose oxidase
Hexokinase method
Poloragraphic method
Glucose oxidase
- B-D glucose + glucose oxidase (enz) + O2 –> D-glucono-&-lactone –> Gluconic acid + H2O2
- H2O2 + peroxidase (enz) + chromogen –> ox-chromogen + H2O
- mutarotase converts a-D glucose to B-D glucose
- can have interference of other substances with peroxidase
Hexokinase method
- most common method used
- less susceptible to interference
- glucose + hexokinase (enz) + ATP –> G-6-P + ADP
- G-6-P + G-6-PD (enz) + NADP –> 6-phosgluc + NADPH + H
Poloragraphic method
- measures rate of O2 consumption with an electrode
- uses glucose oxidase reagent
- eliminate H2O2 produced with molybdate or catalase reactions
Renal glucose limits
glucose is excreted in urine when above renal threshold
Testing for unclear diabetes cases
- 2 of these tests must be positive on separate days
- symptoms + random glucose (> 200)
- fasting glucose > 126
- OGTT > 200
Tests for monitoring diabetes
- Hemoglobin A1C will show glucose control for last 2-3 months (RBC lifespan), normal is < 5.5%
- Look for Ketonemia, Ketonuria with glucose > 300
- Microalbumin increases in urine with glomerular damage
Inborn errors of metabolism leading to hypoglycemia
- Galactosemia
- Fructosuria
- Von Gierke’s
Galactosemia
- decreased galactose-1-phosphatase
- leads to inability to break down galactose to monosaccharide units
Fructosuria
- decreased fructo-1-phosphatase aldolase
- leads to excess fructose in the urine
Von Gierke’s disease
- decreased glucose-6-phosphatase
- enzyme moves glycogen –> glucose into blood
- leads to inability to utilize glucose (can’t break down glycogen and can’t make G6P)
