Quiz 9: Glucose Lab

Normal Glucose-Related Lab Values: Blood Glucose (BG) Levels

variable, depending on timing

normal fasting (no food for >= 8 hours)

- BG <100 mg/dL

normal 2-hour post-Oral Glucose Tolerance Test (OGTT)

- <140 mg/dL

- oral glucose tolerance test: 75g of glucose delivered by oral solution consumed over 5 minutes

Normal Glucose-Related Lab Values: Urine Glucose Levels

normal: negative

glucose does not usually "spill" into the urine until BG >180 mg/dL, when renal threshold for renal glucose reabsorption is exceeded

Normal Glucose-Related Lab Values: CSF Glucose Levels

normal: 50-80 mg/dL (~2/3 of BG)

low CSF glucose levels

- may be associated with hypoglycemia, bacterial/fungal infection, etc.

high CSF glucose levels

- associated with hyperglycemia

Methods of Evaluating Blood Glucose Levels

laboratory blood draw

self-monitoring of blood glucose with point-of-care devices

Normal Glucose-Related Lab Values: Glycated Hemoglobin (AKA "Hemoglobin A1c (HgbA1c)")

normal HgbA1c: 4-5.6%

a red blood cell lives for approx 120 days

hemoglobin is contained in the red blood cell

glucose (sugar) enters in the bloodstream and the red blood cell

glucose naturally binds to hemoglobin

this binding creates glycated hemoglobin (HbA1c)

Normal Glucose-Related Lab Values: C-Peptide Levels

normal fasting C-Peptide: 0.78-1.89 mg/dL

Hypoglycemia: Blood Glucose (BG) Levels

<70 mg/dL

Hypoglycemia: Causes

medication

activities/disease states

Hypoglycemia: Body's Response - Epinephrine

release of counter-regulatory hormones

sympathetic nervous system activation

promotes gluconeogenesis (production of glucose by the liver from lactate, amino acids, and glycerol)

prevents tissues from storing glucose

Hypoglycemia: Body's Response - Glucagon

promotes gluconeogenesis (production of glucose from liver from lactate, amino acids, and glycerol)

promotes breakdown of stored glucose in the liver

prevents glucose from being stored as glycogen within the liver until blood glucose levels normalize

promotes breakdown of triglycerides found in fat tissue into fatty acids that can be used by the muscles for energy

Hypoglycemia: Signs and Symptoms - Mild

54-69 mg/dL

sweating

shaking

trembling

rapid heartbeat

difficulty concentrating

heavy breathing

dizziness

Hypoglycemia: Signs and Symptoms - Severe

<54 mg/dL

mental confusion

unconsciousness

seizure

Hypoglycemia: Treatment - Mild

15 grams of simple carbohydrate (fat and protein slow carb absorption and do not increase blood glucose levels quickly)

- 4 oz fruit juice or soda

- 3-4 glucose tablets

- 8-10 Life Savers candies

re-check blood glucose 15 minutes later

- if BG still <70 mg/dL: re-treat with 15 more grams of carbohydrate

- if BG is >= 70 mg/dL: consume a meal or a long-acting source of sugar (ex. crackers and cheese or a sandwich with meat)

Hypoglycemia: Treatment - Severe

unconscious or unable to swallow

administer glucagon injection follow by treatment described in mild treatment section

if still unconscious after 15 minutes

- repeat glucagon injection and call 911

Hyperglycemia

elevated blood glucose levels

Hyperglycemia: Causes

low levels of insulin production

insulin resistance:

- insulin receptor dysfunction in the muscles, fat, and liver, causing glucose to not be properly taken up from the bloodstream into these cells

medications:

- corticosteroids

- 2nd generation antipsychotics

- thiazide diuretics

- beta blockers

- etc.

Lab Values Diagnostic for PRE-Diabetes: Blood Glucose (BG) Levels

Pre-Diabetes Fasting (no good for >= 8 hours)

- BG: 100-125 mg/dL

Pre-Diabetes 2-hour post-Oral Glucose Tolerance Test (OGTT):

- 140-199 mg/dL

Lab Values Diagnostic for PRE-Diabetes: Blood Glucose (BG) Levels - Pre-Diabetes Fasting (no food for >= 8 hours)

100-125 mg/dL

Lab Values Diagnostic for PRE-Diabetes: Blood Glucose (BG) Levels - Pre-Diabetes 2-hour post-Oral Glucose Tolerance Test (OGTT)

140-199 mg/dL

Lab Values Diagnostic for PRE-Diabetes: Glycated Hemoglobin (AKA "Hemoglobin A1c (HgbA1c)") - Pre-Diabetes HgbA1c

5.7-6.4%

Slide 13: Lab Values Diagnostic for Diabetes (Table 2.1)

*In the absence of unequivocal hyperglycemia, diagnosis requires two abnormal results from different tests which may be obtained at the same time (e.g. A1C and FPG), or the same test at two different time points

Lab Values Diagnostic for Diabetes: C-Peptide Levels

help differentiate between Type 1 and Type 2 DM

C-Peptide levels are low in Type 1 DM

- low insulin production from pancreatic beta cells

C-Peptide levels are normal or high in Type 2 DM

- high C-Peptide levels result from excessive insulin production in response to insulin resistance

C-Peptide levels are ___ in Type 1 DM.

low

C-Peptide levels are _____ in Type 2 DM

normal or high

Low insulin production from _______ ________ _______ in Type I DM.

pancreatic beta cells

High C-Peptide levels result from what in Type 2 DM?

excessive insulin production in response to insulin resistance

Slide 15

*

Slide 16

*

What are the products of fatty acid breakdown?

ketone bodies

Ketone Bodies

produced when glucose and glycogen stores are depleted leading to fatty acids being broken down in the liver

Ketone Bodies: Serum Ketones - Normal Range

<0.6 mmol/L

Ketone Bodies: Serum Ketones - Slightly High

0.6-1.0 mmol/L

Ketone Bodies: Serum Ketones - Moderately High

1.0-3.0 mmol/L

Ketone Bodies: Serum Ketones - Very High

>3.0 mmol/L

Ketone Bodies: Urine Ketones - Normal

negative

Ketone Bodies: Urine Ketones - Positive (Trace)

5 mg/dL

Ketone Bodies: Urine Ketones - Positive (Small)

15 mg/dL

Ketone Bodies: Urine Ketones - Positive (Moderate)

40 mg/dL

Ketone Bodies: Urine Ketones - Positive (Large)

80 mg/dL

Ketone Bodies: Urine Ketones - Positive (Very Large)

160 mg/dL

Desired Lab Values ("Goals") in Patients with Diabetes: Target/Goal Blood Glucose (BG) Levels - Preprandial BG

80-130 mg/dL

Desired Lab Values ("Goals") in Patients with Diabetes: Target/Goal Blood Glucose (BG) Levels - Postprandial (~2 hours after eating) BG

<180 mg/dL

Desired Lab Values ("Goals") in Patients with Diabetes: Target/Goal Glycated Hemoglobin (AKA "Hemoglobin A1c") - HgbA1c

<7%

Desired Lab Values ("Goals") in Patients with Diabetes: Urine Glucose Levels - Normal

negative

glucose does not usually "spill" into the urine until BG>180 mg/dL, when renal threshold for renal glucose reabsorption is exceeded

Consequences of Mild to Moderately Elevated Blood Glucose: Transient

body produces extra insulin to move glucose from extracellular space into cells to lower blood glucose

Consequences of Mild to Moderately Elevated Blood Glucose: Chronic (as seen with Type 1 and Type II Diabetes)

polydipsia

polyuria

polyphagia

nephropathy

neuropathy

retinopathy

Consequences of Severely Elevated Blood Glucose: Hyperglycemic Emergency

Diabetic Ketoacidosis (DKA)

Hyperosmolar Hyperglycemic Syndrome (HHS)

Counseling Points with Diabetes: Health Maintenance

proper diet

- access to healthy food

- transportation

- financial means to pay for healthy food

regular exercise

yearly influenza vaccine

regular doctor's visits

- primary care -> overall care

- podiatrist -> foot care

- ophthalmologist -> eye care

Counseling Patients with Diabetes: Blood Glucose Goals - Pre-Prandial Glucose

80-130 mg/dL

Counseling Patients with Diabetes: Blood Glucose Goals - Post-Prandial Glucose

<180 mg/dL

Counseling Patients with Diabetes: Blood Glucose Goals - A1C

<7%

Diabetes Plate Method: Proportions

1/2 plate non-starchy vegetables

1/4 plate carbohydrate foods

1/4 plate protein foods

4 cups water or 0-calorie drink