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Transcript of Screening, diagnosis and classification of diabetes A. Prof Jonathan Shaw Associate Director Baker...
Screening, diagnosis and classification of diabetes
A. Prof Jonathan Shaw
Associate Director Baker IDI
Melbourne
Page 2: Baker IDI
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
Page 4: Baker IDI
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
Page 5: Baker IDI
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
Page 6: Baker IDI
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
Page 7: Baker IDI
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
Page 8: Baker IDI
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
Page 9: Baker IDI
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
Page 10: Baker IDI
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.
Page 12: Baker IDI
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
Page 13: Baker IDI
Cut-points for diabetes based on
• Identifying a glucose threshold for the presence of complications
• Bi-modal distribution of blood glucose
Page 14: Baker IDI
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
Page 18: Baker IDI
HbA1C for DIAGNOSIS
PRO StableTime averagedReproducibleFasting not required
CON Standardisation essentialExpensiveNot freely availableProblems with anaemia, haemoglobinopathiesPoor QA schemes in many countriesFew data availableCutpoint uncertain
Page 20: Baker IDI
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%
Page 24: Baker IDI
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
Page 26: 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 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