Diagnosis of Type 2 Diabetes & IGT

Question 1

In what 2 ways can T2DM be diagnosed?

Answer 1

• Plasma glucose (Once if symptomatic. Twice if asypmtomatic)
  
  • Fasting glucose >=7 mmol/l
  • Random glucose or OGTT >=11 mmol/l
• HbA1C samples (Once if symptomatic Twice if asymptomatic) - WHO 2011
  
  • >=48mmol/mol (6.5%)
  • Not as sensitive as fasting glucose.

Question 2

In what conditions can HbA1C NOT be used for diagnosis?

Answer 2

1. Type 1 Diabetes - too rapid for HBA1C change
2. Medication - that raise blood glucose
   
   • Steroids
   • Antipsychotics
   • Immunosupressants
   • Antiretroviral drugs
3. Pancreatitis or pancreatic surgery.
4. Pregnancy - HBA1C lower in pregnancy.
5. Increased Red Cell Turnover
   
   • Haemoglobinopathy - Sickle cell, thalassaemia, G6PD, Spherocytosis.
   • Blood loss
6. Increased RBC lifespan
   
   • Anaemias - B12/Folic acid & Iron deficiency & their treatment.
   • Splenectomy.
7. CKD & Renal dialysis - reduced HbA1c especially if treated with erythropoietin.

Question 3

What are the 2 main types of Impaired Glucose Resistance/Pre-diabetes?

Answer 3

1. Impaired fasting glucose (IFG)
2. Impaired glucose tolerance (IGT)

Question 4

What causes impaired fasting glucose?

Answer 4

IFG = Hepatic insulin resistance

Question 5

What is the cause of impaired glucose tolerance?

Answer 5

IGT = Muscle insulin resistance

Question 6

Which patients are more likely to develop CVD, IGT or IFG?

Answer 6

Patients with impaired fasting glucose (IFG)

Question 7

Which patients are more likely to develop T2DM, IFG or IGT?

Answer 7

Patients with impaired glucose tolerance. (IGT)

Question 8

What fasting blood glucose value means you can diagnose impaired fasting glucose (Hepatic resistance)?

Answer 8

6.1 to 6.9 mmol/l

Question 9

What should people with IFG be offered?

Answer 9

They should all be offered an Oral Glucose Tolerance Test (OGTT) to rule out both diabetes and IGT.

Question 10

What blood glucose values do you need to be diagnosed with impaired glucose tolerance (muscle resistance)?

Answer 10

Fasting blood glucose < 7.0mmol/l

AND

OGTT 2 hour value - 7.8mmol/l - 11.1mmol/l

Question 11

What are the normal blood values for fasting, random sugar and HbA1C?

Answer 11

Question 12

How should pre-diabetes be managed?

Answer 12

1. Lifestyle modification
2. Annual blood test follow up.
3. Metformin - high risk adults - blood tests show progressing to T2DM despite lifestyle changes.

Question 13

Steve, how do you remember which diabetes/prediabetes/IGR/IFG/IGT is worse?

Answer 13

Normal —>

Pre-diabetes/Impaired Glucose Resistance (IFG–> IGT) –>

T2DM

Question 14

What HbA1C indicates someone is at high risk of diabetes?

Answer 14

HbA1c of 42-47 mmol/mol.

(Between normal and diabetes)

Question 15

HbA1c reflects the change in blood glucose over what time period?

Answer 15

2-3 months though research is pointing to 2 to 4 weeks.

Question 16

If someone has a high blood sugar and a low HbA1c, what should you expect?

(IGT but HbA1C shows they are not Pre-diabetic)

Answer 16

HbA1c is artificially low. Caused by one of the conditions mentioned in previous slide:

• Lower than expected levels of HbA1c are caused by reduced RBC lifespan:
  
  • Sickle Cell anaemia, G6PD deficiency or Hereditary spherocytosis.
  • Medication - that raise blood glucose. Steroids, Antipsychotics.

NOTE:

Higher than normal levels of HbA1c (Blood sugar normal but HbA1c high) are caused by increased RBC lifespan:

• Vitamin B12/Folic acid deficiency
• Iron-deficiency anaemia
• Splenectomy