Diabetes Mellitus Eiman Ali Basheir Mob: 091520385 27/1/2019
Learning Outcomes Discuss the WHO criteria for Diabetes Mellitus diagnosis Describe the steps taken to confirm diagnosis Interpret GTT. Discuss HbA1C and its significance. Discuss Laboratory tests to prevent and delay complications of diabetes mellitus.
Diagnosis of Diabetes Diagnosis cannot be made from: Blood glucose strips read visually or by a meter. Urine testing Glycosalated Haemoglobin - HbA1c
Diagnosis of Diabetes Two pieces of evidence required Symptoms Random Venous Plasma Glucose > 11.1 Fasting Venous Plasma Glucose > 7.0 2 Hour Venous Plasma Glucose > 11.1 WHO 1999
Action following fasting venous plasma glucose Criteria have been recommended by NZGG for the diagnosis of diabetes, IGT and IFG. Normal Diabetes Fasting glucose result < 5.5 5.5-6.0 6.1-6.9 7.0 Interpretation Normal result Borderline result IFG Diabetic Action Retest in five years or three years for those at risk. OGTT for those at increased risk of diabetes. Re-test annually those with IFG or IGT. Assess with OGTT. Re-test annually Two results > 7 on two different days are diagnostic of diabetes. OGTT is not required. Critieria for the diagnosis of diabetes, IGT and IFG (NZGG, 2003)
Glucose Tolerance Test 3 days of unrestricted diet and exercise Evening meal as normal the night before Overnight fast of 8-14 hours TEST Fasting blood on the morning Drink 75g of anhydrous glucose in 250-300ml water over 5 mins Blood sample 2 hours later No smoking during the test
(WHO,2006) DIAGNOSIS AFTER AN OGTT Impaired Fasting Glucose (IFG) Impaired Glucose Tolerance (IGT) Diabetes Fasting Venous Plasma Glucose 6.1 mmol/l to 6.9 mmol/l <7.0 mmol/l > 7.0 mmol/l 2 hr post < 7.8 mmo/l >7.8 mmol/l up to 11.1 mmol/l >11.1 mmol/l
Interpretation of the glucose tolerance test A 75 gram oral glucose tolerance test (OGTT) is used to follow up people with equivocal results who may have diabetes, IFG or IGT. Fasting mmol/l 2 hours post load mmol/l Normal < 5.5 and < 7.8 IFG 6.1 6.9 and < 7.8 IGT < 7.0 and 7.8 11.0 Diabetes mellitus 7.0 and/or 11.1 GDM 5.5 and/or 9.0 Diagnosis of diabetes, IGT and IFG
Gestational diabetes mellitus Gestational diabetes mellitus (GDM) increases the risk of many foetal and maternal complications in pregnancy and the development of type 2 diabetes later in life. Screening is currently recommended for all women between 24-28 weeks gestation. Screening for GDM using 50 gram load If the one hour blood glucose is 7.8 mmol/l, a two hour OGTT is performed. OGTT for diagnosis of GDM A fasting glucose 5.5 and/or a 2 hour value 9.0 mmol/l is diagnostic of GDM.
Impaired Glucose Regulation Impaired Glucose Tolerance (IGT) - Abnormalities in glucose regulation in the postprandial state. - More common in women Impaired Fasting Glucose (IFG) - Elevated fasting glucose concentrations, but lower than those required to diagnose diabetes - More common in men
Impaired Glucose Regulation IFG and IGT are not interchangeable. Both can lead to diabetes or revert to normoglycaemia Both are associated with an increased risk of Cardiovascular disease Identify & Read Code Adhere to local guidelines regarding follow up
HbA1c Criteria Recently agreed by WHO & Diabetes UK Provides positive identification (ie specific) - If Hba1c > 48mmol/mol, twice or once in prescence of osmotic symptoms, and - if no confounding clinical problems Fails to rule out normality - Hba1c <48mmol/mol does not rule out diabetes - glucose criteria then remain essential Algorithm not widely agreed. Awaiting WEDS approval.
HbA1c > 48mmol/mol Symptomatic Asymptomatic Repeat within 2 weeks HbA1c > 48mmol/mol Type 2 Diabetes Diagnosed
HbA1c < 47mmol/mol Does not exclude Diabetes Hba1c 42 47mmol/mol Lifestyle changes & monitor at least annually Symptoms present exclude diabetes using conventional glucose tests
Under 18yrs Do not use HbA1c Possible Type 1 Where glucose may rise rapidly e.g.: steroids, antipsychotics. Reduced red cell survival e.g. haemolytic anaemia Gestational Diabetes Pancreatic damage/surgery Anaemia/Haemoglobinopathy
Use HbA1c for patients under investigation, or annual assessment of at risk groups including IFG / IGT Metabolic syndrome PMH Gestational Diabetes or large for dates baby (>4kg) Established Vascular disease CVA, IHD, PVD Age > 45 plus +ve Family history Age > 40 (or >30 if Asian or Pacific island descent) with hypertension & BMI>30 PCOS
Do Not Use HbA1c as it is unreliable as a screening tool in: Anyone under age 18 Possible Type 1 Diabetes, e.g. Symptoms of Diabetes for under 2 months or clinically unwell Situations where glucose may rise rapidly e.g. patient on atypical antipsychotics, steroids Patients known to have reduced red cell survival e.g. haemolytic anaemia Gestational diabetes Acute pancreatic damage / pancreatic surgery Anaemia / Haemoglobinopathy
WHO recommendation 2011 1 HbA1c can be used as a diagnostic test for diagnosing diabetes providing Stringent quality assurance tests are in place Assays are standardised to criteria aligned to the international reference values There are no conditions present which precludes its accurate measurement An Hba1c of 48mmol/mol (6.5%) is recommended as the cut point for diagnosing Diabetes. A value of less than 48 mmol/mol (6.5%) does not exclude diabetes, which can still be diagnosed using glucose tests.
Notes Caution: HbA1c should not be used to assess glycaemic status 6 weeks post partum use OGTT HbA1c can also be elevated by: Age. HbA1c is 4.5 mmol/mol higher at 70 than 40 years of age, Ethnicity. Afro-Caribbean and South Asians HbA1c is 4.5 mmol/mol higher than comparable Caucasians
Self monitoring blood glucose (SMBG) People who take insulin should regularly self monitor blood glucose. For people with non-insulin treated type 2 diabetes testing is most useful if patients use the results to learn and alter behaviour, or medication....smbg is most useful if patients use the results to learn, as part of an overall diabetes education package.
Laboratory tests to prevent and delay complications of diabetes People with diabetes usually die from macrovascular complications of their diabetes; namely cardiovascular disease. This is influenced by all of the commonly recognised risk factors for cardiovascular disease as well as glycaemic control. Fasting lipid levels are measured three monthly until stable and then 6-12 monthly thereafter. Parameter Total cholesterol LDL cholesterol HDL cholesterol Optimal value < 4 mmol/l < 2.5 mmol/l > 1 mmol/l It is important that management should be individualised TC:HDL ratio < 4.5 Triglycerides < 1.7 mmol/l HbA 1C < 7 mmol/l
Diabetic renal disease The best way of testing for diabetic renal disease is by urinary albumin:creatinine ratio (ACR) and serum creatinine with estimated glomerular filtration rate (egfr). These tests are performed on everyone with diabetes at diagnosis and repeated at least annually more frequently if there is proteinuria, microalbuminuria or reduced egfr.
Albumin:creatinine ratio ACR provides an estimate of daily urinary albumin excretion. Microalbuminuria cannot be detected on a conventional urinary protein dip stick. Microalbuminuria is urinary albumin excretion between 30 and 300 mg/day; above 300mg/day represents proteinuria. ACR is best measured in the laboratory using a first morning urine sample where possible when the patient is well. An abnormal initial test requires confirmation by testing on two further occasions. If at least one of these tests is positive microalbuminuria has been confirmed.
Renal testing in diabetes ACR mg/mmol (confirmed) egfr ml/min/1.73 2 Risk Management men < 2.5 women < 3.5 and > 60 2-4% per year progress to microalbuminuria. Annual ACR and egfr. Good diabetes & BP management. men 2.5 women 3.5 or < 60 One third progress to overt nephropathy. CVD risk doubled. Review ACR and egfr at each visit. Intensive management of glycaemia and CVD risk factors. Use ACE inhibitor and low-dose aspirin. Avoid nephrotoxic drugs. Investigate if suspicious of causes other than diabetes* > 30 or < 30 Almost all proceed to end stage renal disease or die prematurely of CVD. Overt nephropathy Refer specialist *Non-diabetic renal disease is suspected when there is absence of diabetic retinopathy in a person with renal disease, there are urinary abnormalities such as haematuria or casts, or when there is renal disease without microalbuminuria or proteinuria.
Other Tests Testing of LFTs is recommended for people with diabetes: at diagnosis, at the start of antidiabetic drug therapy, and at any other time indicated by clinical judgement Other laboratory tests In patients with type 1 diabetes, intermittent checks for other autoimmune conditions may be useful. This could include testing for thyroid dysfunction or coeliac disease.
Key points Fasting morning venous glucose is the best initial test for diagnosing diabetes. An oral glucose tolerance test is reserved for people with equivocal fasting glucose results. Patients with impaired glucose tolerance or impaired fasting glucose benefit from lifestyle intervention and annual review. HbA 1C is the best test of glycaemic control in diabetes. Patients with diabetes benefit from aggressive monitoring and management of all cardiovascular risk factors.
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