Diabetes mellitus Regulation of glucose metabolism Insulin a ins. sensitivity vs. resistance Classification of DM PP of primary types of DM – T1DM and T2DM Acute and chronic complications of DM Definition of diabetes mellitus (DM) • DM is a group of metabolic disorders characterized by hyperglycemia resulting from a lack of insulin effect • due to either defect in insulin secretion or insulin action • chronic hyperglycemialeads to long-term cell, tissue & organ damage = diabetic complications • retina • kidney • nerves Fasting vs. absorptive state Regulation of glycemia • humoral • principal • insulin • glucagon • auxiliary • glucocorticoids • adrenalin • growth hormone • neural • sympaticus • hyperglycemia • parasympaticus • hypoglycemia plasma (glycaemia 3–6 mmol/l) FOOD PRODUCTION of GLUCOSE by LIVER CNS A OTHER TISSUES MUSCLE, ADIPOSE TISSUE glykogenolysis inzulin-dependent utilisation non-inzulindependent utilisation glukoneogeneze - pyruvát - laktát - aminokyseliny - glycerol INSULIN GLUCAGON What happens (in healthy man) after meal = insulin orchestrates allocation and utilisation of nutrients diabetic “triumvirate” What happens (in healthy man) after meal = insulin orchestrates allocation and utilisation of nutrients • liver • stimulation of glycogen formation (up to 5% of liver weight) •  hexokinase, phosphophructokinase, glycogensynthase •  G-6-P-kinase • inhibition of gluconeogenesis •  PEPCK • fat formation •  synthesis of FFA and VLDL • proteosynthesis •  transport of AA • inhibition of ketogenesis • muscle • translocation of GLUT4 • formation of glycogen • proteosynthesis •  transport of AA • adipose tissue • translocation of GLUT4 • Glc  glycerol • stimulation of adipogenesis •  activity of LPL • hydrolysisof VLDLand resynthesis of TAG •  hormone-sensitive lipase • brain • insulin participates in the control of appetite/satiety Diagnosis of DM • diabetes • classical symptoms+ random plasma glycemia 11.1 mmol/l (venousplasma) • random= any time of the day • symptoms includepolyuriaandpolydipsia • FPG (fasting plasma glucose) 7.0 mmol/l • fasting means at least 8 h from the last meal • 2-h PG (postprandialglucose)11.1 mmol/l during oGTT • oGTT:according to the WHO consistsof FPG examination followedby a standardloadof 75g of glucose (dilutedin water) and examination ofglycemia in 60th and 120th minute • impaired glucosetolerance (IGT) • excluded<7.8 mmol/l • 2-h PG 7.8 - <11.1 mmol/l during oGTT • impaired fasting glucose (IFG) • diabetesexcludedby FPG 5.6 mmol/l • FPG 5.6 – <7 mmol/l Importance of fasting plasma glucose measurement an intensity of liver glucose productionis a very sensitive „marker“ of insulin sensitivity Q1: The way glucose enters the cell?? glukózaNa+ glukóza INSULIN SECRETION VS. INSULIN SENSITIVITY / RESISTANCE Insulin – world diabetes day • 14/11 (od 1991) • birthday of the man who co-discovered insulin, Frederick Banting • Banting discovered insulin in 1922 alongside Charles Best under the directorship of John McLeod and with assistance of James Collip • The Nobel Prize in Physiology or Medicine 1923 was awarded jointly to Frederick Grant Banting and John James Rickard Macleod "for the discovery of insulin" Langerhans islets - architecture • The pancreaticislet blood flow is 5–10 times higher than that of the exocrinepancreas,and can be selectively enhanced whenever theneed for insulin secretion is increased • B-A-D flow hypothesis • that is why contra-regulation insulin/glucagon works so well Insulin • exocytosis from B-cells of islets of Langerhansinto portal circulation • 50% degraded duringfirst pass through liver • parallel cleavage of the C-peptide • total daily production in healthy subject~20-40U • 1/2 basal (postabsortive)secretion • pulsatile (5 - 15 min intervals) • 1/2 stimulated (postprandial) • early phase (ready insulin) • Glc/KATP-dependent • late phase (synthesis de novo) • other secretagogues • stimulation of secretion • <<> after i.v. Glc • hypoglycemia – if the patient still conscious thenbetter to give Glc per os • “forward”regulatory mechanism – anticipationof increase of Glc • 2 majorincretin hormones • GIP (glucose-dependent insulinotropicpeptide orgastric inhibitory peptide) • GLP-1 (glucagon-like peptide-1) • treatment of T2DM [= delayed effect of Glc on Ins stimulation]by incretin analogues • GLP-1 analogue - exenatide (GLP-receptor agonist) • DPP-4 inhibitors (dipeptyl peptidase 4 - proteolytic degradationof incretins) - gliptins • improvement of Glc-stimulatedIns secretion after meal • supression ofpostprandial glucagon release • delayed gastric emptying • protection ofβ-cells from apoptosis Gula monster (Heloderma suspectum) Gila monster Jens Juul Holst Physiol Rev 2007;87:1409-1439 ©2007 by American Physiological Society Effect of GLP-1 – anticipation of need to rise insulin Incretins have systemic effects too INSULIN SIGNALLING Insulin receptor Insulin receptor made simple • insulin receptor is a tyrosinkinase type (2  and 2  subunits) receptor • signal transduction consists of series of phosphorylation events • intracellular proteins, other kinases and finaly enzymes • i.e. theiractivationorinhibition • activation of anabolic pathways (i.e. glycegenogenesis, lipogenesis) • inhibition of catabolic pathways (e.g. lipolysis, glycogenolysis) and gluconeogenesis • two main effects happen in insulin-dependent tissues • (1)  glucose uptake • by translocationof GLUT4 in sceleatl muscle andadipose tissue • (2) metabolic: IRS  PI-3-K  PDK  PKB (=Akt) •  GSK (glycogen-synthase-kinase)  glycogen synthesis •  cAMP phosphodiesterase  inhibitionof lipolysis •  gluconeogenesis • ubiquitously (3)  gen. expression (mitogenic effect) • MAPK  transcriptionfactors Classification of tissues according to insulin action: • insulin-dependent • skeletal and heart muscle • adipose tissue • in both glucose uptake facilitated by GLUT4, which becomes integratedinto cell membrane after insulinreceptoractivation • liver • metabolicactions • insulin-independent • all others • glucose uptake is realized by facilitated diffusion by GLUT1, 2, 3, 5, … permanently localized in the cell membrane • transport of glucose depends solely on • concentrationgradient • type and density of GLUTs • NOTE skeletal and heart muscle, adipose and liver also express insulinindependent GLUTs Insulin sensitivity – a hyperbolic relation between i. secretion and sensitivity • Insulin sensitivity refers to the body’sability to disposeof glucose • x-axis represents the amountof glucose cleared at a given insulindose • A variety of evidencehas shown that active individualsclear greater glucosewith lower insulin secretion than sedentary individuals • that is, active individualsare more insulin sensitive • becominginactiveand or obese makes you insulinresistant • As sedentary individualsbecome progressively more insulin resistant, pancreaticbeta cells hypertrophy and eventually becomeunable to secrete sufficientinsulin to clear glucose fromthe blood after a meal • This end state is referred to as glucose intolerance Insulin sensitivity assessment • insulin sensitivity (= given effect of dose of insulin on individual‘s glycaemia) is a continuous trait • distinct interindividual variability • it can be assessed by: • hyperinsulinemic euglycemic clamp • calculated indexes (based on relationship between glycaemia and insulin during fasting or oGTT) • e.g. HOMA, QUICKI,… • insulin sensitivity changes (= insulin resistance) in many situations • physiologically inpregnancy • pathologically inobesity,inflammationetc. • should increasing insulin resistance always lead to compensatory increase of insulin secretion than glycaemia would stay stable • however capacity to compensatory increase secretion of insulin by beta-cells is apparently limited CLASSIFICATION OF DM, T1DM A T2DM Pathophysiology of diabetes mellitus • heterogeneoussyndrome characterized by hyperglycemia due to deficiency of insulin action as a result of • absolute insulin deficiency • destruction of the -cells of the islets of Langerhans • relative deficiency of insulin secretion and/or action • abnormal molecule of insulin (mutation of insulin gene) • defective conversion of preproinsulin to insulin • circulating antibodies against insulin or its receptor • insulin resistance in peripheral tissues + secondary failure of -cells of the islets of Langerhans • receptor defect • post-receptordefect • prevalence of DM in general population 5%, over the age of 65 already 25% Prevalence (%) of diabetes (population 20-79 years) 2010– 4.3 bil. (from a total of 7 bil.) 285mil. diabetics 0.75mil. diabeticsin Czechrep. 2030 – 5.6 bil. (from a total of 8.5 bil.) 30% 438 mil. diabetics 54% 1.2 mil.diabetics in Czech Rep. 60% [IDF Diabetes Atlas, 4th ed. International Diabetes Federation, 2009 ] Classification of DM • Diabetes mellitus type 1 (T1DM) 5% • Diabetes mellitus type 2 (T2DM) 90% • Gestational diabetes mellitus (GDM) 10 - 15% of pregnant women • Monogenic DM 2% • neonatal • MODY (1 - 6) • Secondary • diseases of exocrine pancreas • chron. pancreatitis, tumor, cystic fibrosis, hemochromatosis • endocrine disorders (insulin contraregulation) • Cushing syndrome, acromegaly, pheochromocytoma,hyperthyreosis • Drug induced (iatrogenic) DM • glucocorticoidsand others • Other forms (syndromic) • mutation of mitochondrialDNA • genetic defects leading to insulin resistance (type A insulin resistance,leprechaunismus, Rabson-Mendenhal syndrome, lipoatrophic DM) • other genetic syndromes associated with DM (m. Down, Klinefelter, Turner) T2DM Classification of DM 1. Diabetes mellitus type 1 (T1DM) ~5% 2. Diabetes mellitus type 2 (T2DM) ~90% 3. Other specific types: a. genetic defects of B-cell - monogenic DM (MODY1 - 6) - mutation of mitochondrial DNA b. genetic defects leading to insulin resistance - type A insulin resistance, leprechaunismus, RabsonMendenhal syndrome, lipoatrophic DM c. diseases of exocrine pancreas - pancreatitis, tumor, cystic fibrosis, hemochromatosis d. endokrinopathies - Cushing syndrome, acromegaly, pheochromocytoma, hyperthyreosis e. iatrogenic DM (i.e. drugs and toxins) f. other genetic syndromes associated with DM - Down, Klinefelter, Turner syndromes, … 4. Gestational diabetes mellitus From insulin resistance to T2DM • insulin sensitivity changes (= insulin resistance) in many situations • physiologically in pregnancy • pathologically in obesity, inflammation etc. • should increasing insulin resistance always lead to compensatory increase of insulin secretion than glycaemia would stay stable • however capacity to compensatory increase secretion of insulin by beta-cells is apparently limited • main pathophysiologicfeature of T2DM is an imbalance between insulin secretion and its effect • in the time of clinical manifestation there are both insulin resistance and impairment of insulin secretion • what is “chicken” and what is “egg”?? • see later T2DM genetics What determines insulin resistance and/or insulin secretion? • insulin resistance • genetic predisposition (polygenic)– thrifty genotype/phenotype • acquiredfactors • diet – high fat/lowfiber • competitionof Gls withNEFA!!! • obesity – 90% T2DM are obese • effect of adipokines fromadipose tissue (visceral!) • low-grade inflammation • lipid spillover – competitionwithGlc • several other mechaisms • physical inactivity - mobilizationofGLUT4 • down-regulationofins.receptor due to hyperinsulinemia • impairment of insulin secretion • inheritedfactors - genetics • fewer B-cells (~20-40%) • defect of 1. phase of Ins secretion (~80% reduction) • acquiredfactors • – gluco- and lipotoxicity for B-cells Metabolicsyndrome – a unifyingeffect of obesity Genetics of T2DM • Genome-wide association studies (GWAS) have identified over 400 genetic signals that are associated with altered risk of T2DM. Human physiology and epigenomic data support a central role for the pancreatic islet in the pathogenesis of T2DM Genetics of T2DM – a spectrum of impairments Natural history of T2DM – time course Natural history of T2DM – disease mechanisms Insulin- and “sport”-dependent translocation of GLUT4 • 2 intracellular “pools” of GLUT4 • insulin-dependent (see cascade of Ins-receptor) • Ca2+ / NO / AMPK?-dependent • this mechanism is responsible for improvement of insulin sensitivity in physically active subjects Secondary failure of  cells • hyperglycemia induces: • oxidative stress • endoplasmic reticulum (ER) stress • high concentration of NEFA causes lipotoxicity • short term increase of NEFA stimulates secretion of insulin • long term exposure to NEFA, esp. long-chain saturated (e.g. palmitate), suppress secretion of insulin and damages B-cells •  ceramide  apoptosis ER stress  Unfolded protein response • The unfolded protein response (UPR) is activated in response to an accumulationof unfolded or misfolded proteins in the lumen of ER • incl. insulin in -cells • UPR has two primary aims: • initially to restorenormal function of the cell by halting protein translation and activate the signaling pathwaysthat lead to increasingthe productionof molecular chaperonesinvolved in protein folding • if these objectivesare not achieved within a certain time lapse or the disruption is prolonged,the UPR aims to apoptosis Overt T2DM • manifest T2DM is characterized by (variable degree of): • fasting hyperglycemia (due to gluconeogenesis) • insulinresistance inliver • postprandialhyperglycemia (due to decreased peripheral glucose uptake • insulinresistance inmuscle andadipose tissue • mixed dyslipidemia • increased plasma NEFA (due to unsuppressed lipolysis) • insulin resistance in adipose tissue • pro-atherogenic dyslipidemia (due to stimulated VLDL production in liver) • substrate effect GESTATIONAL DM (GDM) Gestational diabetes mellitus (GDM) • GDMdevelops during pregnancy (gestation)and it is one of the most common health problems of pregnancy • up to 10% of expectant mothers • GDMis a serious problem because high blood sugar affect both mother and offspring • GDMpathophysiology • hormonalchanges in physiological pregnancy (i.e. placental hormones) cause mild insulin resistance • this is beneficial for the foetus and baby since glucose is the nutrient and insulin a growth hormone • placenta is ready and glucose-screening test is thus performed typically between 24 and 28 weeks • this requires additional insulin and normal pancreas can keep up with increased demands • if not, blood glucose levels rise too high, resulting in GDM • risk factors: age, overweight/obesity, susceptibility genes for T2DM, diet • maternal hyperglycaemia stimulates baby’s pancreas to produce more insulinto process the extra glucose • as a result baby can put on extra weight (macrosomia) with subsequentcomplications during the birth(shoulder dystocia, fractured bone or nerve damage) • hence the recommendation for early caesarean section • additionally, foetal hyperinsulinemia increases the risk of post-delivery hypoglycaemia • babies who have excessive fat stores as a result of high maternal sugar levels during pregnancy often continue to be overweightin childhood and adulthood (foetal programming) • blood sugar usually returns to normal soon after delivery, however, GDM increases the risk for gettingit again during the future pregnancy and for developing diabetes (T2DM)later in life (up to 50%post-GDM subjects!!!) T1DM T2DM – key points • The incidence of T1DMin childhood has increased and the age at diagnosis has decreased due to environmentalchangesduring the last half of the twentieth century • Inherited defects in central and peripheral immune tolerance (geneticsusceptibility)allow the generation of autoimmune responses directed against pancreatic islets • T1DMas a clinical disease is diagnosed at the end of a prodromeof β-cell autoimmunity • Environmental factors thatmodify the immune system, such as microbiome,infectionsand nutrition, affect the development and course of the autoimmune response • T1DM is a heterogeneous disease with multiple different features,but two majorpathways can be discerned with either insulin autoantibodies or glutamic acid decarboxylase autoantibodiesas the first autoantibodyindicating initiation of the autoimmune process • Multiple trials aiming to prevent development of the disease in different phases of the autoimmune process are ongoing or being planned T1DM genetic susceptibility • selective autoimmune destruction of  cells in genetically predisposed individuals • genetics of T1DM is extremelycomplicated!!! with many population-specificand age-specificeffects • genetic susceptibility • (1) HLA loci – chromosome 6 – MHC class II and I • association with HLA-DR3-DQ2 or HLA-DR4-DQ8 haplotypes (or both) • DR3-DQ2 and DR4-DQ8 • (2) non-HLA loci • chromosome 11 - insulingene • promotor polymorphism(VNTR) affectinsulinexpression in thethymus • PTPN gene = lymphocyte activity • some loci can contributeto initiation of autoimmunedestruction and othersto the rate of progression of the disease • T1DM is therefore a clinically heterogeneous disease • in both cases genetic background leadsto insufficientdeletion of autoreactiveTlymphocytesin thymus and therefore suboptimalcentralimmune(auto)tolerance Crucial role of thymus in establishing a central autotolerance Presentation of peptides by MHC I or II class • MHC loci on the short arm of chromosome 6 represent a most variable part of human genome • this is essential to mount a flexible immune response againstever changing microbial pathogen antigens T1DM autoimmunity principles • (1) genetic background conferred by HLA loci leads to insufficient deletion of autoreactive T-lymphocytes in thymus and therefore suboptimal central immune (auto)tolerance • cytotoxicautoimmunity mediated by T-lymphocytes is a primary driver of the b-cell destruction • CD8+ present in inflammatory infiltration of the Langerhans islets (i.e. insulitis) • CD4+ mediated B-lymphocyte activation towards theauto-antibody production • humoral autoimmunity(antibodiesagainst  cell structures) is a secondary mechanism amplifying the destruction • antibodies are diagnostic and prognostic markers of autoimmunity rather than causalagents • HLA loci contributeto event. clustering of autoimmune diseases • T1DM+ celiac disease • T1DM+ thyreopathy • autoimmune polyendocrine syndrometype 2 (APS-2) =T1DM+ m. Addison + Hashimoto + event. others • (2) non-HLA loci influence • tissue specificity – INS gene • the aggressiveness of the autoimmune process – PTPN gene heterogeneous pattern of antibody panel • early age by autoantibodies primarily directed against insulin or glutamic acid decarboxylase, or both, but rarely against islet antigen-2. After the initial appearance of one of these autoantibody biomarkers, a second, third, or fourth autoantibody against either islet antigen-2 or the ZnT8 transporter might also appear. The larger the number of β-cell autoantibody types, the greater the risk of rapid progression to clinical onset of diabetes. This association does not necessarily mean that the β-cell autoantibodies are pathogenic, but rather that they represent reproducible biomarkers of the pathogenesis T1DM environmental triggers T1DM environmental triggers • autoimmunity has to be triggered by various environmental factors (according to the epidemiologic evidence) • (1) infection • viruses • rubella, measles, coxsackie B, CMV, EBV, enteroviruses, retro-viruses • mechanism is unclear • cytolytic ( sequestration of antigens • formation of neoantigens • molecular mimicry or superantigens • (2) diet – early exposition proteins of cow’s milk plus short breastfeeding • bovine insulin • (3) vitamin D • deficiency correlates with northern-southern geographical gradient? • toxins (diet, water, bacteria) • gluten??? • manifestation typically in childhood • absolute dependence on exogenous supplementation by insulin Natural historyof T1DM Summary of T1DM etiopathogenesis Insulin treatment historically 2 tuny prasečích slinivek  cca 100g inzulinu Insulin treatment nowadays (analogues) Insulin treatment nowadays (analogues) Rare forms of DM • LADA (Latent Autoimmune Diabetes in Adults )= slow-onset T1DM • diagnosis in > 30yrs of age,clinically similar to T2DM(slow onset) • initially ondiet and pills, no ketoacidosis • later insulin dependent (during months – 1 year) • positive antibodies (= autoimmunity), low or no C-peptide • negative family history of T2DM • MODY (Maturity-onset diabetes ofthe young) – cca 5% T2DM • monogenicdiabetes withfamiliarclusteringandwell defined (Mendelian) inheritance (usually AD), early manifestation(childhoodoradolescence) and without obesity • 6 types (MODY1-6) • pathophysiology: genetically conditioned dysfunctionof -cells but long-termmeasurable C-peptide without the signs of autoimmunity • MODY due to glucokinase mutations (MODY2) • glucokinase=“glucose sensor”(impaired insulinsecretion) • milder formwithoutthecomplicationrisk • MODY due to transcription factor mutations (other5 types) • severedefects of -cellsprogressively leadingto diabeteswith complications • impairmentof glucose-stimulated insulinsecretionandproliferation and differentiation of -cells MODY lokus gen produkt prim. defekt závažn o s t k o m p l i k a c e 1 2 0 q HNF4A hepatocyte nuclear factor-4 pankreas vysoká časté 2 7 p GCK glukokináza pancreas/játra mírná vzácně 3 1 2 q TCF1 (HNF1A) hepatocyte nuclear factor-1 pancreas/ledviny vysoká časté 4 1 3 q IPF1 insulin promoter factor-1 pancreas vysoká ? 5 17q TCF2 (HNF4B) hepatocyte nuclear factor-1 pancreas/ledviny vysoká renální 6 2q32 NEUROD1 NEUROD1 pankreas vysoká ? Main characteristics – comparison of T1DM, T2DM and MODY T1DM T2DM MODY onset childhood (≤30 yrs) adults (middle to older age) youth genetic susceptibility yes (oligogenic) yes (polygenic) yes (monogenic) clinical manifestation often acute mild or none gradual/often mild autoimmunity yes no no insulin resistance no yes no (often problem with secretion) dependence on insulin yes no (only in late stages) no obesity no yes no Acute manifestation and long-term consequences (complications) of diabetes Q2: Effect of rising plasma glucose ??? OSMOLARITA = 2 Na+ + urea + glukóza 275 - 295 = 2 x 140 + 2.5 + 5 > 300 = 2 x 140 + 2.5 + 35 Clinical presentation of DM • due to the mild increase of blood osmolarity, osmotic diuresis and dehydratation • classical • polyuria, thirst, polydipsia • tiredness • temporary impairment of vision • others • recurrent infections • perio-/parodontitis • extreme hyperglycemia (>40 mmol/l, osmolarity >350 mosmol/l) • ketoacidosis/coma •  ketone bodies, metabolic acidosis an d hyperglycemia • non-ketoticidotic hyperglycemic coma • hyperglycemia, dehydration and pre-renal uremia • lactic acidosis/coma • either complication of therapy (biguanides / type of peroral antidiabetics) • associated with hypoxic states (sepsis, shock, heart failure, …) Diabetic ketoacidosis • Excessive thirst • Frequenturination • Nausea and vomiting • Abdominal pain • Weakness or fatigue • Shortness of breath • Fruity-scented breath • Confusion Late complications of DM • microvascular • diabetic retinopathy • diabetic nephropathy • diabetickidneydisease (DKD) • diabetic neuropathy • sensoric • motoric • autonomous • macrovascular • accelerated atherosclerosis (CAD, peripheral and cerebrovascular vascular disease) • combined • diabetic foot (ulcerations, amputations and Charcot´s joint) • others • periodontitis • cataract • glaucoma Chronic hyperglycemia Pathogenesis of complications Advanced glycation end products (AGEs) • cross-linking of extracellular proteins • modification of intracellular proteins and DNA • ubiquitin/proteasom • binding to patternrecognition receptors and activation of signaling pathways Maillard reaction in food – AGEs in diet • AGEs are similar to products of Maillard reaction (MRP) formed during thermal processing of food • sugar + protein • Louis Camille Maillard (1878 - 1936) • original descriptionof reactions during cooking (“browning”)leading to formationof MRPs (=AGEs) •MRP influence taste and visual characteristics, smell, shelve life • biologic properties of MRP •positive– antioxidants •melanoidins,polyphenols •negative– carcinogens •acrylamid Pathophysiology of DKD