Dr Aftab Ahmad

Consultant Diabetologist at Royal Liverpool University Hospital

Regional Diabetes Network Lead

HbA1c & diagnosing Diabetes

What is Impaired Glucose & IGR?

Implications of IGR!

Can we manage it?

Regional Diabetes Network’s Role

Is it cost effective to manage it?

Today’s Presentation

1. The previous (1999) WHO diagnostic criteria should

not be changed.

2. The diagnostic cut-point for IFG (6.1 mmol/l) should not be changed.

3. HbA1c should not be adopted as a diagnostic test, as the challenges of measurement accuracy outweighed the convenience of its use.

WHO 2005 Recommendation

1. HbA1c can be used as a diagnostic test for

diabetes providing that:

stringent quality assurance tests are in place and assays are standardised to criteria aligned to the international reference values.

and there are no conditions present which preclude its accurate measurement.

2011 Recommendation By WHO

1. An HbA1c of 6.5% is recommended as the cut point

for diagnosing diabetes.

2. A value of less than 6.5% does not exclude diabetes diagnosed using glucose tests.

Recommendation By WHO

Similar relationship between HbA1C and risk of retinopathy as with FPG and 2-h PG.

Rationale for using HbA1c

Prevalence of diabetes-specific retinopathy ( moderate non proliferative retinopathy) by vigintiles* of distribution of FPG, 2-h PG

and HbA1c from DETECT-2.

Prevalence of retinopathy by 0.5 mmol/L intervals for FPG and 2-h PG and by 0.5% intervals for HbA1c for any retinopathy and diabetes-specific retinopathy ( moderate NPDR) from DETECT-2

The A1C has several advantages to the FPG and OGTT;

including greater convenience (since fasting is not required),

evidence to suggest greater preanalytical stability,

and less day-to-day perturbations during periods of stress and illness.

Advantages of using HbA1c

These advantages must be balanced by: greater cost,

the limited availability of A1C testing in certain regions of the developing world,

the incomplete correlation between A1C and average glucose in certain individuals.

In addition,HbA1c levels may vary with patients’ race/ethnicity

Disadvantages of using HbA1c

HbA1C of 6.5% identifies 1/3rd fewer cases of undiagnosed diabetes than a FPG of 7.0 mmol/L.

However greater practicality and wider application of a more convenient test (A1C) may increase the number of diagnoses made.

Other considerations for HbA1c

HbA1C ≥ 6.5% (48mmol/mol). OR FPG 7.0 mmol/L. Fasting is defined as no caloric intake for at least 8 h. OR 2-h plasma glucose 11.1mmol/L during an OGTT. OR In a patient with classic symptoms of hyperglycemia or hyperglycemic

crisis, a random plasma glucose 11.1 mmol/L.

Criteria for the diagnosis of diabetes

Testing should be considered in all adults who:

are overweight (BMI=25) have one or more additional risk factors:

physical inactivity first-degree relative with diabetes high-risk race/ethnicity (e.g., African American, Latino, Native American, Asian American,

Pacific Islander) women who delivered a baby weighing .9 lb or who were diagnosed with GDM hypertension (blood pressure 140/90 mmHg or on therapy for hypertension) HDL cholesterol level 0.90 mmol/L and/or a triglyceride level 2.82 mmol/L women with PCOS A1C 5.7%, IGT, or IFG on previous testing other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis

nigricans) history of CVD

In the absence of the above criteria, testing at age 45 years.

If results are normal, testing should be repeated at least at 3-year intervals.

Criteria for testing for diabetes in asymptomatic adult individuals

if two different tests are available and the results are

discordant:

the test whose result is above the diagnostic cut point should be repeated, and the diagnosis is made on the basis of the confirmed test.

That is, if a patient meets the diabetes criterion of the A1C (two results 6.5%) but not the FPG (7.0 mmol/L), or vice versa, that person should be considered to have diabetes.

Interpretation

IGR

Individuals with IFG and/or IGT have been referred to as

having IGR or prediabetes, indicating;

the relatively high risk for the future development of diabetes & CVD.

IFG and IGT are associated with: obesity dyslipidemia high triglycerides Low HDL cholesterol, hypertension.

So what is IGR? (Prediabetes)

FPG 5.6 mmol/L to 6.9 mmol/L (IFG)

OR

2-h glucose in OGTT 7.8-11.0 mmol/L (IGT)

OR

A1C 5.7–6.4% (6.0%-6.5% by WHO)

ADA’s Categories of increased risk for diabetes (prediabetes)

Diabetes and lesser forms of glucose intolerance,

impaired glucose tolerance (IGT) and impaired fasting

glucose (IFG), can now be found in almost every

population in the world and epidemiological evidence

suggests that, without effective prevention and control

programmes, the burden of diabetes is likely to

continue to increase globally.

ADA/WHO position on IGR

Studies show a strong, continuous association between

HbA1C and subsequent diabetes.

In a systematic review of 44,203 individuals from 16 cohort studies;

those with an HbA1C between 5.5 and 6.0% had a

substantially increased risk of diabetes with 5-year incidences ranging from 9–25%.

An HbA1C range of 6.0 to 6.5% had a 5-year risk of

developing diabetes between 25 to 50% and relative risk 20 times higher compared with an A1C of 5.0%.

Implication of IGR

Patients with IGT, IFG, or an A1C of 5.7–6.4% (IGR)

should be referred to an effective ongoing support program targeting:

weight loss of 7% of body weight

increasing physical activity to at least 150 min per week of moderate activity.

Follow-up counseling appears to be important for success.

Based on the cost-effectiveness of diabetes prevention, such programs should be covered by third-party payers.

ADA’s PREVENTION/DELAY OF TYPE 2 DIABETES

Metformin therapy for prevention of type 2 diabetes

may be considered in those with IGR, especially for those with:

BMI >35 kg/m2,

age 60 years,

women with prior GDM.

At least annual monitoring for the development of diabetes in those with prediabetes is suggested.

ADA’s PREVENTION/DELAY OF TYPE 2 DIABETES

Standardise management plans across the region.

Develop & help implement pathways.

Support CCGs strategic visions.

Develop local solutions for local problems.

IGR pathway is a prime example.

Regional Diabetes Network’s Role

Merseyside IGR Pathway Identify

High Risk Patients (Box 1)

HbA1c

< 42 mmol/mol

h/o GDM

Clinical/lifesty

le review (Box 2)

No h/o GDM

normoglycaemia

Healthy lifestyle advice

42-47 mmol/mol

IGR

Register of IGR & h/o

GDM

Clinical/lifestyle review

(Box 2)

Self care (Box 3)

IGR education

(Box 4)

Lifestyle referral (Box

5)

≥ 48 mmol/mol (without

symptoms)

Repeat HbA1c

within 2 weeks

≥ 48 mmol/mol

(with symptoms)

≥ 48 mmol/mol

Diabetes Mellitus

North Mersey

Pathway

Merseyside IGR Pathway Identify

High Risk Patients

HbA1c

< 42 mmol/mol

h/o GDM

Register of IGR & h/o GDM

No h/o GDM

normoglycaemia

Healthy lifestyle advice

42-47 mmol/mol

IGR

Register of IGR & h/o GDM

Clinical/lifestyle review

Self care IGR education

Lifestyle referral

BMI . 28 (or >24.5 in South Asians)

Stage 1 Hypertension.

Increased waist circumference.

Family h/o T2 DM.

H/o GDM

Box-1 Individual Risk Factors

CVD risk assessment

Measurements

Lifestyle assessments

Pharmacological review

Preconception counselling

Annual HbA1c & above.

Box-2

Local resource will be developed

Box-3 & 4 Self Care & IGR education

Screen for undiagnosed type 2 diabetes at the first prenatal visit in those

with risk factors, using standard diagnostic criteria.

In pregnant women not previously known to have diabetes, screen for GDM at 24–28 weeks’ gestation, using a 75-g 2-h OGTT and the diagnostic cut points in Table 6.

Screen women with GDM for persistent diabetes at 6–12 weeks’ postpartum, using a test other than A1C.

Women with a history of GDM should have lifelong screening for the development of diabetes or prediabetes at least every 3 years.

Women with a history of GDM found to have prediabetes should receive lifestyle interventions or metformin to prevent diabetes.

DETECTION AND DIAGNOSIS OF GESTATIONAL

DIABETES MELLITUS (GDM)