Chemical Pathology Lesson on Diabetes Mellitus by Professor Aamir Ijaz

PAKISTAN SOCIETY OF CHEMICAL PATHOLOGISTS DISTANCE LEARNING PROGRAMME IN CHEMICAL PATHOLOGY LESSON NO 4 DIABETES MELLITUS (1STPART) By SURG COMMODORE AAMIR IJAZ MCPS, FCPS, FRCP (EDIN) PROFESSOR OF PATHOLOGY / CONSULTANT CHEMICAL PATHOLOGIST BAHRIA UNIVERSITY MEDICAL & DENTAL COLLEGE / PNS SHIFA KARACHI

Q 1: Essential feature for the diagnosis of Diabetes Mellitus (DM) a. Anti-islet cell antibodies b. Glucagon deficiency c. Hyperglycaemia d. Hyperinsulinaemia e. Insulin deficiency Best Answer: c. Hyperglycaemia

Definition of DM By definition DM is a state of Chronic Hyperglycaemia Deficiency of insulin is NOT an essential feature of DM. In fact many type 2 DM patients are Hyperinsulinaemic.

Q 2:Greater genetic predisposition is associated with: a. DM due to acromegaly b. DM due to Cushing Syndrome c. Type 1 DM d. Type 1B DM e. Type 2 DM Best Answer: e. Type 2 DM

Genetics of Type 2 DM (T2DM) Family studies have revealed that first degree relatives of individuals with T2DM are about 3 times more likely to develop the disease than individuals without a positive family history of the disease. It has also been shown that concordance rates for monozygotic twins, which have ranged from 60-90%, are significantly higher than Type 1 DM 30-40% Type I A DM has much greater genetic susceptibility than Type I B DM Thus, it is clear that T2DM has a strong genetic component as compared to Type 1 DM.

Q 3: Fasting Plasma Glucose (FPG) of a 48 year old senior male officer during his Annual Check-up was found to be 7.9 mmol/L (142 mg/dl). He was advised re-testing for DM by Glycosylated Haemoglobin (A1C). The result of A1C was found to be 6.8%. Now he wants your opinion. Keeping in view the latest recommendations by international bodies (and ignoring the social aspects for the time being, at least) which of the following you think is the best option for this patient: a. b. c. d. e. DM is confirmed Requires repeating of FPG Requires repeating of A1C Requires OGTT Requires Urinalysis Best Answer: a. DM is confirmed

Criteria for the diagnosis of diabetes FPG > 7.0 mmol/l (>126 mg/dl) Repeat at interval of at least one week or when stress-free OR Two-hour plasma glucose > 11.1 mmol/l in OGTT OGTT may done due to any indication (see a subsequent slide).

Criteria for the diagnosis of diabetes FPG > 7.0 mmol/l (>126 mg/dl) AND A1C > 6.5% If one of these is higher than the cut-off value repeat the same e.g. if FPG > 7.0 mmol/L and A1C < 6.5% repeat FPG to confirm. If both these tests are above these levels no need to repeat any of the two tests (as the patient in scenario of Q.3).

Criteria for the diagnosis of diabetes (cont) In a patient with classic symptoms of hyperglycemia, a random plasma glucose > 11.1 mmol/L (>200mg/dl) OR A1C > 6.5% .

Criteria for the diagnosis of Pre-diabetes Pre-diabetes: Categories of increased risk for diabetes Impaired Fasting Glucose (IFG) : FPG: 5.6-6.9 mmol/l (100-126 mg/dl) Impaired Glucose Tolerance (IGT) : IGT : 2-h plasma glucose in the OGTT: 7.8-11.0 mmol/l (140 200 mg/dl) Glycosylated Hemoglobin (Hba1c) : 5.7-6.4 %

Indication of OGTT Plasma Fasting glucose between 5.6 mmol/L (100 mg/dl) and 7.0 mmol/L (126 mg/dl) Patients with family history of diabetes mellitus Patients with previous history of large babies Contraindication Plasma Fasting glucose > 7.0 mmol/L (126 mg/dl)

Interpretation of OGTT Based on 2 h Post Glucose Load: Normal: < 7.8 mmol/L (140 mg/dl) IGT: 7.8 11.1 mmol/L (140-200 mg/dl) DM: > 11.1 mmol/L (200 mg/dl)

Q 4: A 42 years male has been recently diagnosed to be having DM at a state-of-the-art Karachi hospital. His medical history indicated development of typical symptoms of DM during 6 months. His BMI is 23 kg/m2. His mother has Rheumatoid Arthritis while a brother has been diagnosed as a case of glomerulonephritis. He is quite diet conscious and spends three hours in Gym per week. Which of the following investigations will be most appropriate for further elucidation of his disease: a. A1C b. Anti- GAD antibodies c. HOMA-IR d. Serum Insulin levels e. Urinary Albumin Best Answer: b. Anti- GAD antibodies

Latent Autoimmune Diabetes in Adults (LADA) Rapid development of diabetic Symptoms. Positive Anti-GAD (Glutamic Acid Decarboxylase Antibodies) or Islet-cell antibodies (ICA) Do not require insulin at diagnosis but progress to insulin dependence after several months to years. Family H/O Autoimmune disorders It is Type 1 DM of adults.

Q 5:. Glucose estimation. Sample collected by which of the following options has the most STABLE glucose results: Various sampling options are available for a. b. c. d. e. Arterial Whole blood collected for ABGs Venous plasma collected in a Lithium Heparin tube Venous plasma collected in a Plain Tube with gel Venous plasma collected in a Plain Tube without gel Venous plasma collected in a Sodium Fluoride tube Best Answer: e. Venous plasma collected in a Sodium Fluoride tube

Q 6: An 18 years obese boy being investigated for DM had Fasting Plasma Glucose (FPG) 6.7 mmol/L (121 mg/l). He underwent OGTT which showed 2 hours post glucose load value as 9.2 mmol/L (166 mg/dl). What is the most probable diagnosis in this patient: a. b. c. d. e. Impaired Fasting Glucose (IFG) Impaired Glucose Tolerance (IGT) Normal Result Type 1 DM Type 2 DM Best Answer: b. Impaired Glucose Tolerance (IGT)

Diagnosis of IGT IGT is defined as Hyperglycaemia at 2 h after glucose load. IFG is FPG between 5.6 and 7.0 mmol/L but normal 2 h after glucose load. So when IGT exists with IFG, IGT takes over and will diagnose the patient as IGT.

T2DM or Pre-Diabetes in Children and Adolescence Type 2DM / Pre-Diabetes is no more a disease of adults It is due to increasing obesity and low fibre diet (fast food). Type 1DM presents with very severe hyperglycaemia and not as pre-diabetes. So the patient in the scenario of Q.6 is NOT of Type 1DM in spite of his young age.

Q 7:. A 48 year male was diagnosed to be having IFG about 4 years ago but now his physician has informed him that he has developed Type 2 DM. His BMI is 31 and his compliance to his physician`s advice about lifestyle has always been quite poor. Which of the following pathological processes is most important in this patient leading to worsening of his disease: a. b. c. d. e. Insulin resistance in adipose tissues Insulin resistance in liver Insulin resistance in muscles Insulin secretory defect at beta cells Insulin synthesis defect Best Answer: a. Decline in -cell function

Q.7 This has very low Difficulty Index (number of students who answered correctly / number of students who answered). The details will be available in Facilitators Feedback Report Its results will not be counted in any contest or statistics. The best answer is Decline in -cell function There were two Plausible Options in this question i.e. Insulin Resistance and Increasing Weight. Their explanation is provided in the subsequent slides.

Pathogenesis of Type 2 DM Insulin Resistance or Impaired Insulin Secretion? Most of the available evidence favors the view that the ultimate triggering event is impaired insulin secretion, which, when superimposed on a background of insulin resistance, leads to overt type 2 DM. Insulin resistance is neither necessary nor sufficient for the development of Type 2 DM but that defective insulin secretion is the primary defect responsible for unmasking overt diabetes.

Pathogenesis of Type 2 DM Insulin Resistance or Impaired Insulin Secretion? (CONT) Although most patients with type 2 DM had some degree of insulin resistance, there are patients with a confirmed diagnosis of diabetes who had no evidence of insulin resistance. These individuals remain normoglycemic by compensating for the reduction in insulin sensitivity with increased insulin secretion

Pathogenesis of Type 2 DM Insulin Resistance or Impaired Insulin Secretion? (CONT) In summary, insulin resistance is an early and characteristic feature of the natural history of type 2 diabetes in high-risk populations. Overt diabetes develops only when the beta cells are unable to appropriately augment their secretion of insulin to compensate for the defect in insulin action.

Pathogenesis of Type 2 DM Impaired Insulin Secretion or Weight Gain? Obesity is a very important predisposing factor in the pathogenesis of Type 2 DM but studies have shown that many obese patients remain normal or with pre-diabetes (IFG or IGT) throughout their lives and never become overt diabetic. Only those obese go into Type 2 DM phase who have in-built insulin secretion defect due to one or more of the genetic and environmental factors. Obesity is a contributory factor mainly to insulin resistance. Here again the real culprit is Impaired Insulin Secretion

An Analogy Remember Margala Tower of Islamabad which had a construction defect. An Analogy During Oct 2005 earthquake, only Margala Tower collapsed and many precious lives were lost but other buildings were unaffected or minimally damaged (IFG or IGT). But the solution is to avoid earthquake !!! Not Possible? In DM it is possible by Total Life Style Change i.e. reducing weight and physical activity.

Q 8: A1C is a well-recognized marker used for monitoring of DM. While working in a tertiary care hospital you want to switch this test to a more sensitive and specific method. Please answer following queries in this regard: a. standardization of this test b. Name the current technique widely used now for this test at many well-reputed laboratories. c. What is the ONE most important advantage of using this test for the diagnosis of DM as recently recommended? Name the international organization which provides technical d. diagnosis in our country. Name TWO major challenges for use of this test for the e. Name one group of disorders in which the test gives poor clinical correlation even when carried out by a modern method.

Suggested Answer Q.8 a International organizations which provides technical standardization The National Glycohemoglobin Standardization Programme (NGSP) certified methods and reagents having documented traceability to the Diabetes Control and Complications Trial Reference Method. International Federation of Clinical Chemistry (IFCC) Reference method of HbA1c (Mentioning either of these two was sufficient for this question)

Glycosylated Haemoglobin (A1C) Assay A1C is difficult to assay as compared to Glucose or colourimetric assays. In 1993 a vary large study was published called DCCT (Diabetes Complications and Control Trial). In this study A1C was established was used as the main outcome rather than Plasma Glucose in Type 1 DM patients. In 1998 a similar study UKPDS (United Kingdom Prospective Diabetes Study) was published in Type 2 DM patients. Again A1C was the main outcome. (We will discuss these two studies in Lesson No 5-DM-2nd Part).

Glycosylated Haemoglobin (A1C) Assay (Contd) So it was decided by a major International Body of Chem Path (AACC) that for A1C same methods should be used as used in DCCT or UKPDS But there was a major problem in Standardization of A1C. In 1993, data showed that there was a lot of variability among methods measuring different glycated Hb fractions i.e. measurement of Hb A or Hb A1c or other fractions. Clearly this was not acceptable for achieving specific A1C goals.

Glycosylated Haemoglobin (A1C) Assay (Contd) In 1996, NGSP was formed to implement the AACC programme. Manufacturers usually give details about the traceability of their method to NGSP. But manufacture`s claim should be verified by consulting the NGSP data from their website (List attached with this ppt).

IFCC Reference Methods IFCC has developed two reference methods for HbA1c analysis: Mass spectroscopy Capillary electrophoresis.

Units of A1C NGSP Methods: HbA1c % of total Hb IFCC Methods mmol/mol of Hb

The relationship between NGSP (%HbA1c) and the IFCC (mmol/mol) A master equation has been developed: NGSP = [0.09148 x IFCC] + 2.152.

Estimated Average Glucose Estimated Average Glucose (eAG) is a new way to talk to patients about diabetes management. The measurement of A1C expressed as a percentage is usually not very clear to patients who uses gucometer or lab values. This may make A1C targets difficult for patients to translate into action. Doctors can now report A1C results to patients using the same units (mg/dl or mmol/l) that patients see routinely in blood glucose measurements.

Estimated Average Glucose The relationship between Estimated Average Glucose (eAG) and HbA1c based on linear regression analysis was: eAG (mg/dl)= (28.7xA1C)-46.7 Or eAG (mmol/l)=(1.59xA1C)-2.59 You can calculate at fol link: http://professional.diabetes.org/Glucos eCalculator.aspx

Estimated Average Glucose A1C% eAG (mg/dl) eAG (mmol/L) 5 97 5.4 6 126 7.0 7 154 8.6 8 183 10.2 9 212 11.8 10 240 13.4 11 269 14.9 12 298 16.5 (

Suggested Answer Q.8 b Currently techniques used for this test at many well-reputed laboratories Ion-exchange HPLC TINIA

Suggested Answer Q.8 c One most important advantage of using this test for the diagnosis of DM The sample can be collected at any time of the day and fasting state is not required.

A1C as Diagnostic Test of DM In 2009 ADA finally recommended A1C to be used as diagnostic test. After a lot of resistance, WHO also endorsed this recommendation in 2011 and A1C is now widely used as diagnostic test. The biggest advantage is fasting state is not required. Merely dispensing with this requirement of fasting has lead to broadening of screening base and many of those patient can be screened who cant get their test done in fating state.

Other Advantage of A1C for Diagnosis and Monitoring of DM Standardized and aligned to the DCCT/UKPDS while measurement of glucose is less well standardized Better index of overall glycemic exposure and risk for long-term complications Substantially less biologic variability Substantially less pre-analytic instability Relatively unaffected by acute perturbations Currently used to guide management and adjust therapy

Suggested Answer Q.8 d TWO major challenges of using A1C for diagnosis in our country: 1. High cost : Several hundred per test as compared to Rs. 10-20 per test. 2. Non-Standard methods: probably our Lab persons are not even aware of the standardization etc.

Suggested Answer Q.8 e Group of disorders in which the test gives poor clinical correlation: Heamoglbinopathies

Q 9: You have conducted an interactive session on Classification of DM with your PG Trainees. Now you have received some queries by email form one of the PGs. Please answer her queries related to WHO Classification of DM: a. Why the older names Insulin Dependent DM and Non-Insulin Dependent DM have been replaced by new terms like Type1 DM and Type 2 DM? b. Similarly why terms like Juvenile onset and Maturity Onset have been abandoned for Type 1 and Type 2 DM, respectively? c. Why Maturity Onset Diabetes of the Young is placed in 3rd etiological category i.e. other specific types and not in Type 2 DM. d. Does a patient of Type 2 DM, when on high dose of insulin, become a patient of Type 1 DM?

Classification of diabetes Type 1 diabetes -cell destruction Type 2 diabetes Progressive insulin secretary defect Other specific types of diabetes Genetic defects in -cell function, insulin action MODY Disease of the exocrine pancreas Drug or chemical-induced Gestational diabetes mellitus

Clinical Stages of DM (WHO) a. Normoglycaemia b. Impaired Glucose Regulation Impaired Fasting Glycaemia (IFG) Impaired Glucose Tolerance (IGT) c. Diabetes Mellitus (DM) DM not requiring insulin DM requiring insulin for Control DM requiring insulin for Survival

Suggested Answer of Q. 9 a Why the older names Insulin Dependent DM and Non-Insulin Dependent DM have been replaced by new terms like Type1 DM and Type 2 DM? Type 1 and Type 2 are etiological classes recommended by WHO in 1999. Older terms indicates treatment modalities. A type 2 patient may become dependent on insulin at later stages.

Suggested Answer of Q. 9 b Similarly why terms like Juvenile onset and Maturity Onset have been abandoned for Type 1 and Type 2 DM, respectively? Although majority of type 1 has its onset in early age, it can occur later in life as well and similarly a lot of young people/ adolescents can have type 2 Diabetes starting earlier in life. So age as a criteria for type1 and 2 were abolished.

Suggested Answer of Q. 9 c Why Maturity Onset Diabetes of the Young is placed in 3rd etiological category i.e. other specific types and not in Type 2 DM? MODY is a group of monogenetic disorders while Type 2 DM is polygenetic disorders MODY is characterized by insulin deficiency and not insulin resistance while Type 2 DM both are important.

Suggested Answer of Q. 9 d Does a patient of Type 2 DM, when on high dose of insulin, become a patient of Type 1 DM? No. Type 1 DM and Type 2 DM are two different etiological classes.

Q 10: A Naib Qasid, 51 y of age has been referred to you by a friend of yours for advice on humanitarian grounds. This poor chap is quite confused about his disease. The story starts with his reporting to a General Physician (GP) for early fatigability and calf pain. The GP gave some symptomatic treatment and advised Blood Glucose Random which came out to be 135 mg/dl or 7.5 mmol/L (ref range : 80-200 mg/dl). Since the value was within given range he was declared normal and no specific treatment was given. Totally unsatisfied he went to another doctor who repeated the test but this time in fasting state. The result was 115 mg/dl or 6.4 mmol/L (ref range upto 100 mg/dl). He was advised Tab Daonil (1/2 tab Daily) by the doctor. Hearing this story, plz answer these questions about this patient: a. Why there is a discrepancy between the glucose reports, assuming there is no analytical error in the tests? b. In your opinion which of the test is more reliable? c. In which category of the disease you will place this patient and what will be your exact label for this patient? d. Name a test you will like to carry out in this patient for the exact diagnosis of glucose disorder? e. Is giving a Sulfonylurea appropriate in this patient?