360 - Glucose & Diabetes

Question 1

Hypoglycemia in diabetes may be the result of…

Answer 1

defective glucagon secretion or by a decreased epinephrine response to hypoglycemia

hypoglycemia in nondiabetic adults may be differentiated as fasting or postprandial hypoglycemia

Question 2

fasting hypoglycemia

Answer 2

most commonly associated with drugs such as ethanol and salicylates

Question 3

Postprandial hypoglycemia

Answer 3

associated with drugs such as insulin, antibodies to insulin or insulin receptors and inborn errors of metabolism

Question 4

Whipple Triad

Answer 4

hypoglycemia diagnosis is made when an individual meets this criteria

Question 5

insulin-dependent diabetes or immune-mediated diabetes.

Answer 5

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

Question 6

the result of insulin resistance with or without defective secretion of insulin

Answer 6

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

Question 7

Gestational diabetes mellitus

Answer 7

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

Question 8

prediabetes

Answer 8

• 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

Question 9

complications of diabetes

Answer 9

retinopathy, neuropathy, angiopathy, nephropathy,
infection, and dyslipidemia and atherosclerosis.

Question 10

how often should adults get screened for diabetes

Answer 10

every three years using fasting blood glucose or HbA1C

Question 11

how is diabetes diagnosed?

Answer 11

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

Question 12

purpose of the OGTT test

Answer 12

evaluate glucose clearance from the circulation after loading with a defined dose and under controlled conditions

Question 13

T or F. glucose is diurnal

Answer 13

T! OGTT performed between 7 to 9 am

Question 14

OGTT procedure

Answer 14

• 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*

Question 15

specimen conditions for glucose testing

Answer 15

• 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

Question 16

interferences in hexokinase method for glucose

Answer 16

• gross hemolysis, extreme icterus and lipemia = neg interference
• NOT affected by ascorbate or uric acid

Question 17

glucose oxidase method specimen and interferences

Answer 17

only suitable for blood and CSF; not urine bc of uric acid interference

Hb, bili, ascorbic acid can inihibit the rxn as well

Question 18

T or F. whole blood has lower glucose levels than plasma or serum

Answer 18

T! POCT instruments use whole blood

Question 19

what is HbA1C and what is its purpose?

Answer 19

• can diagnose and monitor diabetes
• Hb A1C is hemoglobin A that has become
  irreversibly bound to glucose, glycated

Question 20

how are HbA1C levels determined?

Answer 20

HPLC chromatography or immunoassay

Question 21

fruoctosamine

Answer 21

the non-enzymatic attachment of glucose to amino groups of proteins other than
hemoglobin, e.g. albumin

Question 22

T or F. serum protein turnover is faster than Hb

Answer 22

T

Question 23

how is fructosamine measured?

Answer 23

chromatography and photometric methods

Question 24

this is used to monitor the kidney function of ppl w diabetes

Answer 24

urine albumin:creatinine ratio

Question 25

The ideal urine specimen for measuring albuminuria is a 24-hour collection. However, 24-hour urine collections present many
challenges, so…

Answer 25

• 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

Question 26

what happens when there is a decreased use of carbs for energy production?

Answer 26

• 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

Question 27

how is B-hydroxybutyrate detected?

Answer 27

colorimetric method
gas chromatography-mass spec

Question 28

if metabolic acidosis is suspected, what should a physician order?

Answer 28

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

Question 29

intermediary product of carbohydrate metabolism and is derived mainly from muscle cells, medulla of the kidney, and erythrocytes

Answer 29

lactic acid

Question 30

how does blood lactate level rise?

Answer 30

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

Question 31

two types of lactic acidosis

Answer 31

• 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

Question 32

specimen for lactate

Answer 32

• potassium oxalate, or heparinized blood on ice
• NO TOURNIQUET
• specimen should be immediately cooled & separated
• lactate will increase rapidly due to glycolysis

Question 33

lactate dehydrogenase

Answer 33

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