T2DM Flashcards
composition of islets of Langerhans
- beta cells produce insulin to lower BG by increasing glucose uptake, marcomolecule synthesis, and inhibition of TG breakdown
- alpha cells produce glucagon to raise BG via liver glycogenolysis and gluconeogenesis
- delta cells produce somatostatin
- F cell produce pancreatic polypeptide
diabetes overview
- diabetes is a group of metabolic disease characterized by hyperglycemia
- type I is the inability to regulate BG due to deficient insulin secretion from beta cells
- type II is the inability to reg BG due to lack of insulin sensitivity in normally insulin-sensitive tissues
glucose regulation
1. insulin
2. exercise and glucose uptake
- insulin increases the speed of glucose uptake from blood into cells, with insulin res lose the ability stim translocation of GLUT4 transporter (how majority glucose gets transported), still able to transport glucose through GLUT1 but much slower, BG rises
- exercise can induce GLUT4 translocation, allowing skeletal muscle to act as a glucose sink
T1DM therapeutic intervention
1. monitoring glucose
2. exogenous insulin
3. insulin delivery
- BG measured throughout day to keep BG in noroglycemic range (70-180 mg/dL)
- since beta cells cannot produce insulin, deliver exogenous insulin; 4 types: rapid-acting controls spike, short-acting is regular insulin peaking at 2-3 hr, intermediate-acting allows peak in 4-12 hrs, and long-acting with no peaks working over 24 hr
- insulin injected into subQ fat with needle, modern ver use BG monitor which detects increase in glucose and signal tube under skin to release of rapid-acting insulin from pump
diabetes epidemiology
1. overview
2. T2DM risk factors
- type I and type II affect 15% if pop; with 5-10% T1DM and 90% T2DM; diabetics x3 more likely to be hospitalized with CVD
- age due to dysreg of cellular functions, POC, family history of T2DM or genetic factors; symptoms of MetS, obesity, poor lifestyle choices
T2DM clinical manifestations
1. non-specific clinical manifestation
2. long term manifestation
3. mechanisms and pathogenesis
- have symptoms of MetS such as overweight, dyslipidemia, hyperinsulinemia, and high BP; fatigue, classical symptoms of polyuria, polydispsia, and polyphagia (too much urination, drinking, and eating); unexplain weight loss due to poor metabolic cycling (glucose cannot be uptaken, fats and proteins are broken down to provide fuel); recurrent infections (high BG breakdown neural and vascular tissue) and poor wound healing (breeding ground for organisms consuming glucose)
- microvascular and macrovascular complications and steatohepatitis
- due to B cell dysfunction, insulin res, whole body chronic inflammation
insulin resistance and altered beta cell physiology
dysregulation of BG feedback sys begins when too much glucose is in body for long time, beta cells become stressed/overactive and hypertrophy to compensate for high BG; beta cells fail, ratio of alpha to beta cells increase and beta cell sensitivity decrease, dev glucolipotoxicity and insulin res; beta cells then undergo differentiation and death, decreasing beta cell mass by 30-40% leading to diabetes
genetic vs. lifestyle factors of T2DM
- mother > father T2DM risks; SNP in adipocyte TCF7L2 (Wnt signalling pathway) increase risk by 10-20% and in vitro or in vivo inactivation of TCF7L2 increase adipocyte hypertrophy and insulin res; however 55% of people w/o T2DM have risk allele so influence of genetics is less than influence of lifestyle
- obesity is the single most important predictor; 90% of cases are preventable by following healthy habits
multiorgan cause of chronic hyperglycemia: adipose tissue
- adipose tissue produce leptin and adiponectin, obesity increases leptin decreases leptin sensitivity, gen less satiety
- decreases adiponectin decrease BG reg high food intake increase BG, increases inflammation and decrease insulin sensitivity
- adiposity assoc with high amounts of serum (bound to albumin) FFAs, inflammatory cytokine TNF alpha, and decrease insulin receptor density, all of which increase inflammation and insulin sensitivity
multiorgan cause of chronic hyperglycemia: pancreas
altered inuslin and glucagon signaling, decrease amylin (beta cell hormone secreted with insulin to increase saitety and decrease glucagon release)
multiorgan cause of chronic hyperglycemia: GI tract
Increase ghrelin (stim hunger and food intake) produced in GI cells for insulin res and decrease fasting insulin; decreased beta cell sensitivity to GLP1 and GIP (big moderating factor of insulin secretion)
multiorgan cause of chronic hyperglycemia: kidneys
reabsorb glucose from urine using sodium glucose cotransporter 2, high glucose saturates SGLT2 and left over glucose goes into urine but high uptake at kidneys worsens hyperglycemia
multiorgan cause of chronic hyperglycemia: brain
manages satiety, insulin, and glucose detection, brain uses 20% of body glucose at rest; high glucose cause neuroinflammation, GLUT1 and GLUT3 have impact on neuro condition such as Alzheimers
- inflammation in dysfunctional adipose cells
- dev of insulin res
- functional adipocytes have high amounts of O2, able to produce lots of ATP; dysfunctional addipocyte stores high amt of TG, hypertrophied, less O2 per cell, decrease ATP production leading to cell death and secrete TNF alphha which recruites macrophages to release more inflammatory cytokines
- TNF alpha inhibit IRS, blocking downstream cascade at the start; cannot uptake FFA to be stored and move FFA to blood thus high serum FFA
- insulin signalling in skeletal muscle on metabolism
- adiposity on dev of insulin res
- insulin bind to receptor, IRS trigger signalling cascade to bring in glucose and FFA; conversion of FFA produce ceramides and DAG, DAG converted to TAG (triacylglycerol) for fuel; GLU either converted to glycogen or metabolize by mitocondria
- bring in high amount of circ FFA, accumulating high amounts of ceramides and DAG, DAG inhibit IRS and thus insulin signalling and ceramides dysregulate AKT and PKB for GLUT4 translocation, less GLU uptake; mitocondria working harder to use up extra E, breakdown due to excessive use due to gen of high amounts of reactive oxidative species