2 - Glucose Regulation + Diabetes Mellitus Flashcards
What is glucose regulation?
The process of maintaining optimal blood glucose levels
What is euglycemia?
Normal blood glucose (4-7 mmol / L)
Identify the 3 factors that interact to regulate glucose
1) caloric intake
2) hormones (insulin, cortisol, glucagon)
3) glucose uptake by the cells for energy
What is glycogen?
Stored glucose in liver + fat cells
What is gluconeogenesis?
Process by which glycogen is converted to glucose
What is hyperglycemia?
high blood sugar ( > 11 mmol / L)
What is hypoglycemia?
low blood sugar (< 4 mmol / L)
What is glycolysis?
breakdown of glucose to pyruvic acid
What is glucagon?
Glucagon is a glucoregulatory peptide that counteracts the actions of insulin by stimulating hepatic glucose production and thereby increasing blood glucose levels - released when our BG is so low
What is the function of epinephrine in glucose regulation?
when blood glucose levels frop too low - the adrenal glands secrete epinephrine which causes the liver to convert stored glycogen to glucose (gluconeogenesis) thereby raising blood glucose levels
What is the function of GH in glucose regulation?
exerts anti-insulin activity by suppressing insulin’s ability to promote glucose uptake in the peripheral tissues; increases gluconeogenesis in the liver
What is diabetes mellitus?
Disorder of the endocrine clels of the pancreas involving a deficiency of insulin function, either:
- decreased secretion
- insulin resistance
or both
Where are the pancreatic A + B cells located?
In the islets of langerhans
What do pancreatic A cells secrete?
glucagon
What do pancreatic B cells secrete?
insulin
What is insulin?
Insulin is a protein hormone made exclusively by pancreatic B cells.
Why can’t we ingest insulin orally?
Because it is a protein hormone
Once synthesizd, where is insulin stored? How is it secreted?
Stored in vesicles
Secreted via exocyosis when needed
How can we tell if diabetics still have some function in their pancreatic B cells?
We can tell by checking for trace amts of connecting peptide (C-Peptide) in their blood.
People who make their own insulin will have some of this C-Peptide in their blood
Exogenous insulin (by needle) doesn’t have C-Peptide so there won’t be any C-Peptide in someone’s blood who can’t make their own insulin.
What is the primary stimulus for insulin secretion? What are some other stimulants for insulin secretion?
High blood glucose.
Also amino acids + acetylcholine.
What inhibits insulin secretion?
Alpha-adrenergic stimulation
Beta-blockers
How do the pancreatic B cells secrete insulin?
B cells have secretory granules containing stored insulin inside them.
When our blood glucose increases, ATP binds to and inhibits ATP-sensitive potassium channels
Causes the B cell to depolarize which allows calcium to enter the cells which triggers the release of insulin
What is the role of insulin?
Insulin stimulates the conversion of glycogen to glucose + stimulates glucose uptake from the blood into fat and muscle cells
Also stimulates mvmt of potassium into the cells.
what are the 4 types of diabetes?
1) type 1 (IDDM)
2) type 2 (NIDDM)
3) miscellaneous
4) gestational
Describe Type 1 Diabetes.
When do symptoms occur?
What is the age of onset and how do the pts often present?
Type 1 Diabetes is an autoimmune disease - represents 10% of diabetic cases.
Immune system attacks our pancreatic B cells
Symptoms occur when more than 70% of the B cells are eliminated; eventually all B cells are irribersibly lost and insulin secretion is virtually nonexistent.
Type 1 pts will require life-long exogenous insulin therapy (shots) and are often referred to as insulin-dependent diabetics (but this is not the clinical term used anymore)
Age of onset is typically under the age of 30
Pts often present as non-obese w muscle wasting
Describe Type 2 Diabetes in terms of its etiology and key characteristics.
Represents 90% of all cases.
Etiology is unknown - however 80% of pts are obese (particularly adominal / central obesity), and 80% have a family history
Key characteristic is peripheral insulin resistance w decreased insulin-stimulated glucose uptake; Hepatic glucose output is increased
In an attempt to compensate for insulin resistance, the pancreas increases its secretion of insulin causing hyperinsulinemia. Over time the pancrease becomes “exhausted” / dysfunctional, resultin in defective insulin secretion + diabetes.
Typically adult onset
Many pts do not require insulin treatment (“NIDDM”) b/c some residual insulin function remains
Describe type 3 diabetes.
“miscellaneous” category
represents many causes of primary or secondary DM
primary: monogenetic disorders (Ex - mature onset diabetes of the youth [MODY]
secondary: diabetic symptoms that occur as a consequence of something else (pancreatitis, pancreatic cancer, cystic fibrosis, hemochromatosis, glucocorticoid excess, hyperthyroidism, drug / infection induced
describe type 4 (gestational) diabetes
diabetes diagnosed during a pregnancy that typically resolves after birth.
occurs in 5-10% of pregnant women in canada
caused by increased levels of hormones w CRH effects
risk increases w subsequent pregnancies
type 4s have an increased risk for developing type 2 diabetes in the future
associated w increased birth weight and adverse maternal and fetal outcomes
What is the fundamental manifestation of diabetes?
hyperglycemia
What is the fundamental manifestation of diabetes?
hyperglycemia, especially fasting + postprandial
What is the glucose tolerance test?
Clinical tool used to evaluate fasting P postrpadial hyperglyceemia.
A pt is instructed to fast over night and we take their base BG
Pt then consumes a 75g glucose load and we test their BG every 30 minutes for 2-3 hrs
The test is +ve (aka pt is diagnosed as diabetic) when the BG exceeds 7 mmol / L OR when the blood glucose exceeds 11.1 mmol / L during the 2 hr follow-up
What is prediabetes (also called impaired glucose tolerance or impaired fasting glucose)?
When BG is elevated but not enough to be diagnosed as diabetic. Implies that diabetes is imminent and the pt should be treated as if they are.
What is the HBA1C test?
a test used to measure the amount of glycosylated hemoglobin - determines if BG has been elevated at any time over the previous 90-120 days.
Which percentage of glycosylated hemoglobin is normal? Which percentage indicates that a pt is diabetic?
normal: 5%
> 6.5 % = diabetes
What are the 4 early manifestations of diabetes?
1) glucosuria (glucose in the urine)
2) polyuria (freq. passage of large volumes or urine)
3) polydipsia (excessive thirst + excess drinking)
4) polyphagia (excessive or extreme hunger)
Why does glucosuria occur as an early manifestation of diabetes?
glomerular filtration of glucose is greater than the renal tubule’s ability to reabsorb [occurs when the SGLTs (sodium dependent glucose transporters)] become saturated - therefore some glucose remains and is excreted in the urine
Why does polyuria occur as an early manifestation of diabetes?
glucose in the urine impairs the osmosis of water - leads to osmotic diuresis - then polyuria
Why does polydipsia occur as a manifestation of diabetes?
Dehydration occurs due to polyuria.
What are the clinical manifestations of hyperglycemia?
- glucosuria
- polyuria
- polydipsia
- polyphagia
- abdominal cramps
- blurred vission
- headache
- nausea + vomiting
- weakness
- fatigue
- nocturia
- glucosuria
- hungies
What are the risk factors for severe hyperglycemia (there are lots)?
- taking corticosteroids
- emotional + physical stress
- illness, infection
- inactivity
- poor absorption or lack of insulin
- too little or lack of diabetes meds
- lack of knowledge regarding diet
- inaccurate knowledge on administration of insulin
- non-adherence to mgmt of blood glucose
- lack of undrstanding regarding the importance of self-monitoring blood glucose
- elderly pt
define glycosylation
process by which glucose non-enzymatically binds to plasma + blood vessel proteins
What is Diabetic Ketoacidosis?
Absence of insulin function results in uncontrolled lipolysis + ketogenesis
Keto acids enter the blood and cause metabolic acidosis which results in the formation of ketone bodies
In which type of diabetes does DKA commonly occur?
Type 1 - typically w a missed insulin dosage
Rarer in type 2 because residua insulin function inhibits profound lipolysis + ketogenesis
What will happen if DKA is left untreated?
coma + death
What are the 3 manifestations of DKA?
1) severe hyperglycemia
2) metabolic acidosis
3) rapid respirations + fruity breath
What is severe hyperglycemia?
BG > 25 mmol / L
Why does fruity breath occur as a manifestation of DKA?
Pt has rapid, deep respirations (kussmaul) to compensate for metabolic acidosis (to try lower the amt of CO2 in the blood)
ketones spontaneously convert to acetone in the blood which vaporize in the alveoli and give the breath a characteristic fruity odor
What is the treatment for DKA?
IV insulin therapy + fluid mgmt K+ supplement b/c: - insulin increases the cellular uptake of K+ - K+ is lost in the urine + vomit - K+ diluted w fluids
What is the cause of hypoglycemia?
occurs when there is too much insulin in proportion to the amt of available glucose in the blood which causes the plasma glucose to drop
Occurs w over-administration of drugs, w exercise, fasting or a missed meal, or excessive alcohol consumption
When do the neurogenic / autonomic (SNS stimulatio) symptoms of hypoglycemia occur?
when blood glucose in below 3.5 mmol / L
When do the neuroglycopenic (CNS depression) symptoms of hypoglycemia occur?
appear when the blood glucose is below 2.5 mmol / L
Why do neurogenic symptoms occur due to hypoglycemia?
Related to the release of epinephrine
Why do neuroglycopenic symptoms occur due to hypoglycemia?
CNS shutdown - occur when the brain isn’t getting enough glucose.
What are the neurogenic / autonomic symptoms of hypoglycemia?
sweating tachycardia trembling anxiety weakness palpitations light-headedness nausea irritability
What are the neuroglycopenic symptoms symptoms of hypoglycemia?
confusion irritability headaches drowsiness loss of coordination difficulty speaking convulsions seizures coma
What are the potential treatments of hypoglycemia?
- oral or IV glucose (15 g or more to stabilize their BG)
- IV glucagon (glucagon triggers stored glucose in the liver - so if the pt hasn’t eaten in a long time the IV glucagon won’t work)
- repeated bouts of hypoglycemia or beta-blocker use can reduce the SNS response
What is hyperosmolar coma?
Results from hyperosmolarity (hyperglycemia + dehydration) - cellular dehydration of CNS neurons is believed to be the cause of this coma
What is HHNS?
Hyperosmolar hyperglycemic non-ketotic syndrome
blood sugar is super high, pt is dehydrated and they are losing consiousness
What is HHNC?
Hyperosmolar hyperglycemic nonketotic coma - progression from HHNS
What usually precipitates episodes of HHNS?
these episodes are often precipitated by inadequate fluid intake during another illness; infection, HF, or MI are often contributing factors; decreased GFR
Why are pts asymptomatic for much longer with HHNC?
Because there is no ketoacidosis with HHNC - therefore this delays medical care.
How high can BG reach in the case of HHNC?
45-100 mmol / L
How much higher is the mortality rate in HHNC than DKA?
x 10 higher
How do we treat HHNC?
F - fluids I - insulin G - glucose (monitor) P - potassium I - infection C - chart fluid balance K - ketones
T or F: insulin can cause lethal arrhythmias due to hypokalemia from potassium uptake into the cells
true
What are the 4 chronic complications of diabetes mellitus?
1) microangiopathy (microvascular disease)
2) macroangiopathy (macrovascular disease)
3) neuropathy
4) infections + foot ulcers
provide 2 examples of microangiopathy associated with DM
- retinopathy
- nephropathy
Provide 3 examples of macroangiopathy associated w DM
- coronary artery disease
- cerebral artery disease
- peripheral artery disease
Why does microangiopathy (disease of the small vessels) occur in DM?
- basement membranes of capillaries are thickened in diabetes + contain an increased amt of collagen and decreased amts of proteoglycan - makes the vessels stiff + rigid
- w prolonged hyperglycemia, more glucose irreversibly binds to proteins creating advanced end glycosylation end products (AGE)
- AGEs cause the accumulation of basement membrane proteins, capture LDLs, and rhe release of inflammatory cytokines
Diabetes is the leading cause of adult-onset blindness. What are the 2 stages of diabetic retinopathy?
1) non-proliferative stage
2) proliferative stage
Describe the non-proliferative stage of diabetic retinopathy
- microaneurysms occur in the retinal blood vessles as a result of microangiopathy and loss of pericytes
- aneurysms can become permeable or can rupture resulting in retinal exudate formation and hemorrhage
- retinal ischemia, infarction, and visual impairment ensue (ex - blind spots)
describe the proliferative stage of diabetic retinopathy
worse than the non-proliferative stage
retinal ischemia stimulates angiogenesis and new blood vessels form w/in the retina - infarction of the retina causes fibrous scar tissue to replace the necrotic neural tissue
fibrous tissue accumulates, tension increases in the retina, and often results in retinal detachment + blindness.
Does the proliferative stage of diabetic retinopathy occur more frequently in type 1 or type 2 DM?
Type 1
T or F: Diabetes is the leading cause of end-stage chronic renal failure requiring dialysis and transplant
true
What is diabetic nephropathy? What is the first sign?
primarily involves the glomerular capillaries.
fibrosis and thickening of the capillary basement membrane occurs (glomerularsclerosis) - nephrons are lost and renal failure occurs
the first sign is microalbuminuria (b/c proteoglycan is lost which allows albumin to enter the tubules and then the urine), also see elevated BUN + creatinine
What are the 3 main drug classes used to treat diabetic nephropathy?
1) ace inhibitors
2) ARBs
3) SGLT2 inhibitors
describe diabetic macroangioathy
essentially describes how diabetes accelerates atherosclerosis
AGEs (advanced glycosylation end products) w/in blood vessels capture more LDL, activate more macrophages and inflammatory cytokines, and promote the proliferation of vascular cells - all of which accelerate atherosclerosis
how much higher is the prevalence of coronary artery disease in diabetics?
which percentage of diabetics will die from atherosclerotic related illnesses?
x 2-4 higher
80%
which medications are most often prescribed for diabetic macroangiopathy?
statins + blood presure meds like ace inhibitors or arbs
what are the 2 estimated causes of diabetic neuropathy?
combined consequence of microangiopathy and the accumulation of sorbitol w/in neurons
complication of microangiopathy in which nutrient delivery to neurons is impaired
what are the 2 types of diabetic neuropathy?
- symmetrical distal polyneuropathy
- autonomic neuropathy
Describe symmetrical distal neuropathy
demyelination of distal peripheral nerves is the hallmark of this neuropathy.
usually manifests as symmetric sensory loss in the lower extremities (ex - stocking distribution, numbness, tingling
Describe autonomic neuropathy
affects autonomic innervation of many different systems
fixed, resting tachycardia and orthostatic hypotension are signs of cardiovascular involvement.
incomplete emptying of the urinary bladder (ex – neurogenic bladder) causes overflow incontinence and predisposes to urinary tract infection.
50% of diabetic men suffer from impotence related to vascular and autonomic dysfunction. female sexual dysfunction has been less studied (OF COURSE), but failure to achieve orgasm has been reported
a decreased glucagon and epinephrine response to hypoglycemia, and exertional hypoglycemia can also occur.
T or F - hyperglycemia is a pro-inflammatory phase
true
what are the long term consequences of hyperglycemia?
- blood vessel damage
- peripheral neuropathy
- fluid + electrolyte imbalances
- acid base disturbances
what are the long term consequences of hypoglycemia?
- seizures
- LOC
- hypoglycemia unawareness syndrome
- death
what are the steps we can take to address mild-moderate hyperglycemia?
- adjust meal plan
- adjust physical activity
- adjust meds ot insulin
- increase hourly intake of water / fluids
what are the steps we can take to address severe hyperglycemia?
- medical attention required
- monitor serum glucose
- fluid replacement + short-acting insulin by IV
- monitor and treat electrolytes + renal function
- monitor neurological status
what are the risk factors for severe hypoglycemia?
- prior episodes of severe hypoglycemia
- current low A1C ( < 6.0%)
- hypoglycemia unawareness
- long duration of insulin therapy or sulfonylureas
- autonomic neuropathy
- chronic kidney disease
- cognitive impairment
- low socio-economic status, food insecurity
- low health literacy
- preschool-age children or adolescents
- pregnancy
- elderly pts
what are the risk factors for type 2 diabetes?
- age over 40
- first-degree relative w type 2 diabetes
- member of high risk population (asia, african, arab, hispanic)
- history of prediabetes
- history of GDM
- delivery of a macrosomic infant
- presence of end-organ damage associated w diabetes
- vascular risk factors (HTN, overweight, abdominal obesity, smoking)
describe the differences between type 1 and type 2 diabetes
type 1: destruction of beta cells leading to lack of insulin
type 2: progressive loss of beta cell function, cellular insulin resistance
type 1: cannot be managed w diet or exercise alone
type 2 can be managed w diet, exercise, oral antihyperglycemics or insulin
How often should we screen individuals over 40 and individuals at high risk for type 2 diabetes?
how often should we screen for people with additional risk factors?
every 3 years.
every 6-12 mo for people with additional risk factors
What do the following lab results indicate? How often should we rescreen?
- FPG < 5.6 mmol / L or A1C < 5.5%
This is normal. Rescreen as recommended.
What do the following lab results indicate? How often should we rescreen?
- FPG 5.6-6.0 mmol / L or A1C 5.5-5.9%
This pt is at risk - rescreen more often.
What do the following lab results indicate? How often should we rescreen?
- FPG 6.1-6.9 mmol / L or A1C 6.0-6.4%
Pt is prediabetic - recreen more often.
What do the following lab results indicate? How often should we rescreen?
- FPG greater than or equal to 7.0 mmol / L or A1C greater than or equal to 6.5%
Pt is diabetic.
What is the critical high level for blood sugar?
Critical low?
33 mmol / L
2.8 mmol / L
why is infection more likely to occur in DM?
- decreased immune response
- delayed wound healing
- glucose is fuel for microorganisms
- diabetes is a pro-inflammatory state. increases cytokines in the blood
- worsened blood flow
what is lipodystrophy?
hypertrophy of fat cells
What is the dawn phenomenon?
takes place early in the morning
growth hormone is released during the night which decreases peripheral glucose uptake - causing hyperglycemia
w the sun rise, a rise in the blood glucose concentration occurs w no hypoglycemia during the night.
T or F: insulin is also used in the case of severe hypercalcemia
True :)
Identify the 3 risk factors shared between diabetes + heart disease
1) high BP
2) obesity
3) high cholesterol
on a h2t assessment of a diabetic pt, describe what we would look for.
CNS: LOC, neuropathy
CVS: HR, BP, cap refill, CWCM
RESP: Kussmaul resps, crackles, fruity breath
GI / GU: NVD, diet, appetite
INTEGUMENT: sores, ulcers, signs of infection, open areas
MSK: weakness, activity levels, muscle wasting, intermittent claudication, activity tolerance
