Post on 17-Dec-2015
Screening, diagnosis and classification of diabetes
A. Prof Jonathan Shaw
Associate Director Baker IDI
Melbourne
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Identifying people at risk of developing type 2 diabetes• Test everyone – mass screening
• Test people who have risk factors for diabetes
• Undertake large-scale, non-invasive, self completed screening, with a validated tool, followed by blood tests for those at high-risk– FINDRISK– AUSDRISK
AUSDRISK•Self-completed risk score
•Developed and validated on Australian data
•Calculates 5-yr risk of developing diabetes
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1. Your age group?Under 35 years 0 pts35 – 44 years 2 pts45 – 54 years 4 pts55 – 64 years 6 pts65 years or over 8 pts
2. Your gender?Female 0 ptsMale 3 pts
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3. Ethnicity/Country of birth:3a. Are you of Aboriginal, Torres Strait Islander, Pacific Islander or Maori descent?
No 0 ptsYes 2 pts
3b. Where were you born?Australia 0 ptsAsia 2 ptsMid-East, N Africa 2 ptsS Europe 2 ptsOther 0 pts
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4. Have either of your parents, or any of your brothers or sisters been diagnosed with diabetes (type 1 or type 2)?
No 0 ptsYes 3 pts
5. Have you ever been found to have high blood glucose (sugar) (e.g. in a health examination, during an illness, during pregnancy)?
No 0 ptsYes 6 pts
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6. Are you currently taking medication for high blood pressure?
No 0 ptsYes 2 pts
7. Do you currently smoke cigarettes or any other tobacco products on a daily basis?
No 0 ptsYes 2 pts
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8. How often do you eat vegetables or fruit?
Everyday 0 ptsNot everyday 1 point
9. On average, would you say you do at least 2.5 hours of physical activity per week (eg 30 minutes a day on 5 or more days a week)?
Yes 0 ptsNo 2 pts
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10. Your waist measurement taken below the ribs (usually at the level of the navel)?
For those of Asian or Aboriginal or Torres Strait Islander descent:Men Women< 90 cm < 80 cm 0 pts90 – 100 cm 80 – 90 cm 4 pts>100 cm > 90 cm 7 pts
For all others:Men Women< 102 cm < 88 cm 0 pts102 – 110 cm 88 – 100 cm 4 pts> 110 cm > 100 cm 7 pts
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Your risk of developing type 2 diabeteswithin 5 years:
≤ 5: Low riskApproximately one person in every 100 will develop diabetes.
6-14: Intermediate riskFor scores of 6-8, approximately one person in every 50 will develop diabetes.For scores of 9-14, approximately one person in every 20 will develop diabetes.
15 or more: High riskFor scores of 15-19, approximately one person in every seven will develop diabetes.For scores of 20 and above, approximately one person in every three will develop diabetes.
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Diagnostic thresholds should be defined by• Their association with clinically meaningful
abnormalities
• Level above which intervention is effective
• Associations with intermediate (metabolic) disturbances
• Normal limits of a healthy population– mean + 2SD– 9?th percentile
• Bimodal distribution
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Cut-points for diabetes based on
• Identifying a glucose threshold for the presence of complications
• Bi-modal distribution of blood glucose
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Cut-points for diabetes based on• Identifying a glucose threshold for the
presence of complications
• Bi-modal distribution of blood glucose
Relative risk of CVD mortality by 2-hr glucose - DECODE
6
5
4
3
2
1
0
Rel
ativ
e ri
sk
0 2 4 6 8 10 12 14 16 2-hour plasma glucose (mmol/l)
<3.0>14.5
Normal IGT Diabetes
Limitations of associations with complications
• Thresholds have been based on micro- not macrovascular disease
• Estimates of threshold values are imprecise (variation between populations, wide limits of deciles)
• All data are cross-sectional – longitudinal analyses would be likely to give lower cut-points
• ‘Diabetic retinopathy’ occurs at non-diabetic glucose levels
• Studies need to have more cases of retinopathy, and be able to use more severe levels of retinopathy
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HbA1C for DIAGNOSIS
PRO StableTime averagedReproducibleFasting not required
CON Standardisation essentialExpensiveNot freely availableProblems with anaemia, haemoglobinopathiesPoor QA schemes in many countriesFew data availableCutpoint uncertain
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PLASMA GLUCOSE for DIAGNOSIS
PRO DM is disorder of raised glucoseTime honouredMuch dataAllows international comparisonsAccurate assay (?)
CON Based on cross-sectional data in relatively small numbers of studiesMajor pre-analytical problemsOGTT required – FPG inadequateOften poor QA
Page 21: Baker IDI Diabetes Care July 2009
Recommends using HbA1c as the preferred diagnostic test for diabetes
at a cut-point of 6.5%
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POSSIBLE 2009 WHO CLASSIFICATION OF DIABETES MELLITUS
1. Type 1 diabetes (-cell destruction)
2. Type 2 diabetes
3. Other specific types
4. Gestational diabetes mellitus
5. Undefined
ADA, WHO, 1997
Classic Onset Type 1
Age of onset
Usually under 30 Usually 30 - 60 Usually over 30 years (except for MODY)
Present-ation
Rapid onset of thirst, polyuria, weight loss
Gradual onset of milder symptoms
Often asymptomatic; may present with complications or gradual onset of symptoms. 85% obese. Part of Metabolic Syndrome.
Ketonuria Usually present May be absent Absent (except with severe stress eg infection, infarction)
Anti-GAD antibodies
Present in approx 80% at diagnosis
C-peptide level
Low or absent, but may be low-normal initially (remission phase)
Normal-high (ie hyperinsulinemia)
Treatment Insulin required urgently to prevent ketoacidosis
Insulin required, but not urgently
Healthy eating and exercise, may require oral agents, and/or insulin later
Classic Onset Type 1 Slow Onset Type 1(LADA)
Type 2
Absent
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Summary• Screening
– Begin with non-invasive score
– Blood testing in those with a high score
• Diagnosis– HbA1c may become an accepted test
– Clinical diagnosis requires confirmation with a 2nd test
• Classification– Differentiation between type 1 and 2 increasingly difficult
– For most patients, classification, and need for insulin can be determined on simple, clinical criteria
Page 27: Baker IDI
Summary• Screening
– Begin with non-invasive score
– Blood testing in those with a high score
• Diagnosis– HbA1c may become an accepted test
– Clinical diagnosis requires confirmation with a 2nd test
• Classification– Differentiation between type 1 and 2 increasingly difficult
– For most patients, classification, and need for insulin can be determined on simple, clinical criteria
Page 28: Baker IDI
Summary• Screening
– Begin with non-invasive score
– Blood testing in those with a high score
• Diagnosis– HbA1c may become an accepted test
– Clinical diagnosis requires confirmation with a 2nd test
• Classification– Differentiation between type 1 and 2 increasingly difficult
– For most patients, classification, and need for insulin can be determined on simple, clinical criteria
Page 29: Baker IDI
Summary• Screening
– Begin with non-invasive score
– Blood testing in those with a high score
• Diagnosis– HbA1c may become an accepted test
– Clinical diagnosis requires confirmation with a 2nd test
• Classification– Differentiation between type 1 and 2 increasingly difficult
– For most patients, classification, and need for insulin can be determined on simple, clinical criteria