360 - Glucose & Diabetes Flashcards
Hypoglycemia in diabetes may be the result of…
defective glucagon secretion or by a decreased epinephrine response to hypoglycemia
hypoglycemia in nondiabetic adults may be differentiated as fasting or postprandial hypoglycemia
fasting hypoglycemia
most commonly associated with drugs such as ethanol and salicylates
Postprandial hypoglycemia
associated with drugs such as insulin, antibodies to insulin or insulin receptors and inborn errors of metabolism
Whipple Triad
hypoglycemia diagnosis is made when an individual meets this criteria
insulin-dependent diabetes or immune-mediated diabetes.
Type I DM
- the insulin-producing cells of the pancreas are destroyed by the host immune system
- presence of one or more Abs
- treatment: insulin + meal planning
- prone to ketosis
the result of insulin resistance with or without defective secretion of insulin
Type II DM
- there are normal levels of blood insulin; however, the action of insulin at the cells is
defective
- the beta cells of the pancreas produce more insulin => death of cells and eventually decreased the secretion of insulin
- treatment: lifestyle modification (exercise, diet), meds such as insulin may be required
Gestational diabetes mellitus
a temporary condition characterized by glucose intolerance that begins or is first recognized during pregnancy
- usually asymptomatic
- both mother and child are at increased risk of developing diabetes
prediabetes
- high risk for TII
- abnormal fasting, OGTT, or HbA1c but do not neet criteria for DM diagnosis
- some can revert to normal glycemia but can at high risk for CV disease
complications of diabetes
retinopathy, neuropathy, angiopathy, nephropathy,
infection, and dyslipidemia and atherosclerosis.
how often should adults get screened for diabetes
every three years using fasting blood glucose or HbA1C
how is diabetes diagnosed?
fasting blood glucose >7.0mmol/L or an
HbA1C ≥6.5%
- individuals at higher risk or with indeterminate results, additional and more frequent testing is recommended
- also diagnosed by 2-hour OGTT ≥11.1 mmol/L
purpose of the OGTT test
evaluate glucose clearance from the circulation after loading with a defined dose and under controlled conditions
T or F. glucose is diurnal
T! OGTT performed between 7 to 9 am
OGTT procedure
- fasting blood glucose specimen is drawn
- patient ingests a 75 g glucose drink within 5 minutes
- second blood specimen drawn after 2 hours.
- test for pregnant women is the same except an additional specimen collected after 1 hour*
specimen conditions for glucose testing
- serum or plasma
-separated immediately = glycolysis occurs fast at RT in whole blood - glucose stale for 8hrs at RT in separated sample
- sodium fluoride can temporarily inhibit glycolysis
- leukocytosis + bacterial contam = decrease glucose
- 24 hr urine should be collected with 5mL glacial acetic acid to inhibit contam
- urines ref
- CSF analyzed immediately
interferences in hexokinase method for glucose
- gross hemolysis, extreme icterus and lipemia = neg interference
- NOT affected by ascorbate or uric acid
glucose oxidase method specimen and interferences
only suitable for blood and CSF; not urine bc of uric acid interference
Hb, bili, ascorbic acid can inihibit the rxn as well
T or F. whole blood has lower glucose levels than plasma or serum
T! POCT instruments use whole blood
what is HbA1C and what is its purpose?
- can diagnose and monitor diabetes
- Hb A1C is hemoglobin A that has become
irreversibly bound to glucose, glycated
how are HbA1C levels determined?
HPLC chromatography or immunoassay
fruoctosamine
the non-enzymatic attachment of glucose to amino groups of proteins other than
hemoglobin, e.g. albumin
T or F. serum protein turnover is faster than Hb
T
how is fructosamine measured?
chromatography and photometric methods
this is used to monitor the kidney function of ppl w diabetes
urine albumin:creatinine ratio
The ideal urine specimen for measuring albuminuria is a 24-hour collection. However, 24-hour urine collections present many
challenges, so…
- the ratio of albumin to creatinine is measured instead
- the ratio of albumin to creatinine
corrects for variations in the patient’s hydration status - first-morning void
- ACR of 3 mg/mmol or more should be regarded as clinically significant
what happens when there is a decreased use of carbs for energy production?
- fatty acids metabolized = acetyl coA
- occurs during prolonged starvation or impaired carb metabolism (DM)
- mitochondria = acetyl coA converted to acetoacetate; if accumulates = acetone or B-hydroxybutyrate
how is B-hydroxybutyrate detected?
colorimetric method
gas chromatography-mass spec
if metabolic acidosis is suspected, what should a physician order?
quantitative B-hydrobyturate
- acetone only tested when ingestion is suspected
- AHS tests for B-hydroxybutrate on unspun whole blood (lithium, EDTA)
- specimen stable for 2 hrs at RT or 48 hrs refrigerated
intermediary product of carbohydrate metabolism and is derived mainly from muscle cells, medulla of the kidney, and erythrocytes
lactic acid
how does blood lactate level rise?
severe oxygen deprivation = tissue blockage of aerobic oxidation of pyruvic acid in TCA cycle
pyruvate reduced to lactate instead of to acetyl coA
= lactate:pyruvate ratio increases
two types of lactic acidosis
- Type A is more common and is associated with severe tissue hypoxia
- Type B is metabolic and is associated with diabetes mellitus, liver disease, drugs such as
ethanol, methanol and salicylates as well as inborn errors of metabolism
specimen for lactate
- potassium oxalate, or heparinized blood on ice
- NO TOURNIQUET
- specimen should be immediately cooled & separated
- lactate will increase rapidly due to glycolysis
lactate dehydrogenase
alkaline pH (9.0-9.6) lactate dehydrogenase oxidizes lactate to pyruvate, which is accompanied by the reduction of NAD+ to NADH. An increase in absorption is measured at 340 nm
