Diabetes Mellitus Flashcards
What cells release insulin?
beta cells found in the islets of Langerhans of the endocrine portion of the pancreas
What type of disease is type 1 Diabetes Mellitus?
Type 4 Hypersensitivity Reaction where pancreatic islet cells undergo autoimmune destruction
What kills the beta cells of the pancreas in type 1 Diabetes Mellitus?
Type 4 Hypersensitivity, cell-mediated (CD8+ lymphocytes invade islets, target and kill beta cells) + autoAb against cells
What population is most affected by Type 1 DM?
Children
Is type 1 DM associated with genetic mutations? If so, which ones?
Mutations in HLA-DR3 and HLA-DR4
Is insulin treatment needed for type 1 DM?
Always
Is type 1 DM associated with obesity? Type 2?
Type 1, no, then to be thin. Type 2 usually associated with obesity
Is there a genetic predisposition associated with Type 1 and 2 DM? If so, is it weak or strong? How many genes are involved?
Yes
Type 1 = weak predisposition, polygenic
Type 2 = strong predisposition, polygenic
Is type 2 DM associated with genetic mutations? If so, which ones?
No
What is the glucose intolerance for type 1 diabetes? Type 2? (mild-moderate-severe)
Type 1 = severe
Type 2 = mild to moderate
Is insulin treatment needed for type 2 diabetes?
Sometimes
What is the pathophysiology of Type 2 DM?
insulin resistance (cells cannot properly respond to insulin) + decreased insulin secretion (endocrine pancreas deficient, cannot raise insulin levels to compensate for insulin resistance) + high glucagon levels
What risk factors are associated with Type 2 DM?
obesity (especially those w/ excess intra-abdominal fat (visceral fat))
Sedentary lifestyle (low exercise, high triglycerides diet, smoking, alc consumption, sleep duration)
Family hx
Ethnicity (Asian, Hispanic, and African American at higher incidence)
Polycystic Ovary Syndrome
Inflammation + secretion of cytokines by adipocytes
What population is type 2 DM most seen?
Obese adults, can still see it in children and non-obese
What is the identical twin concordance rate of getting type 2 diabetes?
70-90%
What syndrome is strongly associated with type 2 DM? How can this present?
Metabolic syndrome, seen as overweight/obese due to visceral fat
What type of DM is associated with ketoacidosis? Can it be seen with the other type?
Type 1 DM, is rare with type 2 DM
How are pancreatic cells affected in type 2 DM?
are present but have decreased insulin secretion
What are the serum insulin levels in type 1 DM?
Very low or zero
What are the serum insulin levels in type 2 DM?
Variable, often high
How many patients in type 1 DM have autoAb against islet cells? What about in type 2?
Type 1: 85%-95%
Type 2: 5%-10%
What are the general sxs of diabetes? What are they caused by?
Polyuria, Polydipsia, polyphagia –> caused by hyperglycemia
Why do we see polyuria, polydipsia, and polyphagia in DM?
hyperglycemia causes increased glucose secretion by the K, results in osmotic diuresis as water follows (polyuria). Increased fluid excretion causes hypovolemia, increased thirst (polydipsia). Although there is hyperglycemia, glucose can’t enter cells = low energy, increased appetite (polyphagia)
What is one short term consequence of hyperglycemia and is seen with diabetes?
irreversible glycosylation of Hb, forms Hb A1C
What are the diagnostic tests used for DM?
Fasting blood glucose, glycated Hb (HbA1C), random venous blood glucose, and oral glucose tolerance test
What is the cut-off value for diagnosing DM using fasting blood glucose? What should be kept in mind? What about for Hb A1C, random venous blood glucose, and oral glucose tolerance test?
FBG = ≥126 mg/dL, must fast for ≥8 hrs HbA1C = ≥6.5%, results can be influenced by other conditions RVBG = ≥200 mg/dL, only use for pts w/ hyperglycemia sxs OGTT = serum glucose ≥200 mg/dL 2hr after pt ingests glucose
What can affect accuracy of HbA1C test?
can be influenced by other conditions such as CKD and hemolytic anemia
What comorbidities are associated with obesity?
HTN
Hyperlipidemia = higher incidence of non-alcoholic fatty liver disease + increased fat around neck can cause obstructive sleep apnea
How many of the 4 tests used to dx DM must be abnormal when pt has no hyperglycemic sxs?
2 abnormal results of the 4 tests
Which of the 4 tests used to diagnose DM requires pt to show sxs of hyperglycemia?
Random venous blood glucose
What is a benefit of HbA1C?
tracks glucose levels over the past 3 months
How is HbA1C formed?
glucose attaches to Hb via nonenzymatic glycosylation in high glucose environment
Why does HbA1C last for 3 months?
Stays in body until RBC turnover (120 days)
What is C-peptide?
pt cleaved from pro-insulin as it matures to insulin active form, released with insulin
What can C-peptide tell us?
If insulin is made or not
What are the expected levels of C-peptide in type 1 DM? Type 2 DM?
Type 1 - no insulin is made, so low or zero C-peptide
Type 2 - insulin levels normal, if a bit low later on so C-peptide will be normal or a bit low
What antibodies can be used to diagnose type 1 DM? Type 2? What do they target?
Type 1 = glutamic acid decarboxylase autoAg Ab + Islet cell cytoplasmic autoAg Ab
Type 2 = autoAb only in 5-10% of pts so much less likely
What is the first treatment for DM if it is not life-threatening?
lifestyle modifications = Balanced diet high in fiber, low in fat and refined/simple carbs (sucrose, fructose)
When do you give insulin therapy to pts w/ type 1 DM? What about type 2?
Type 1 = immediately since can’t produce insulin
Type 2 = only if can’t control w/ diet and multiple oral agents to decrease glucose (metformin)
What is the pathophysiology of Type 1 DM? What is this process called?
APC presents Beta-cells with autoantigens to CD4 T cells → release cyk → recruit T and B lymphocytes → direct cytotoxic and Ab-mediated destruction of pancreatic beta cells
= lymphocytic infiltration insulitis
What do they autoAb target in type 1 DM?
pancreatic iselt cells and glutamic acid decarboxylase (which controls insulin release from beta cells)
What does the serum glucose level have to be to see polyuria?
> 240 mg/dL
What type of DM do you see weight loss associated with? What about weakness?
Type 1 DM, cells cannot uptake glucose and use it as food or energy source
What is the common acute complication associated with type 1 DM? What is this caused by?
Diabetic Ketoacidosis = hyperglycemia + metabolic acidosis
What clinical presentation can polyuria result in?
dehydration, hypotension, dry mucous membranes, increased capillary refill time, decreased skin turgor