287-291. Type 1 Diabetes

Question 1

What levels would be expected for FASTING BLOOD GLUCOSE in a patient who is:

a) Normal
b) Impaired
c) Diabetic

Answer 1

a) Less than or equal to 6
b) Betwen 6.1 and 6.9
c) More than or equal to 7

Question 2

What levels would be expected for an ORAL GLUCOSE TOLERANCE TEST (OGTT) 2hr glucose in a patient who is:

a) Normal
b) Impaired
c) Diabetic

Answer 2

a) Equal to or less than 7.7
b) 7.8 - 11
c) More than or equal to 11.1

Question 3

What is the diagnostic criteria for diabetes mellitus?

Answer 3

Need two abnormal tests (fasting blood glucose, OGTT), or 1+ symptoms

Question 4

What is the range for the HbA1c test in someone with prediabetes?

Answer 4

42-47

Question 5

What value would be seen in a HbA1c test for someone who is diabetic?

Answer 5

> 48

Question 6

List the 4 main types of diabetes

Answer 6

Type 1 (prevalence 0.5%)
Type 2 (prevalence 5%)
MODY (autosomal dominant, prevalence 0.1%)
Gestational

Question 7

What are some of the causes of secondary diabetes?

Answer 7

Pancreatitis
Cycstic fibrosis
Haemochromatosis
Steroid-induced
Acromegaly

Question 8

What types of diabetes are insulin DEFICIENT?

Answer 8

Type 1
MODY
Pancreatitis
Cystic fibrosis
Haemochromatosis

Question 9

What types of diabetes are insulin RESISTANT?

Answer 9

Type 2
Gestational
Steroid-induced
Acromegaly

Question 10

There are many different types of autoantibodies which can be involved in the development of T1DM. Name 5 of them

Answer 10

1. ICA (islet cell antibody)
2. I-A2 (insulinoma-associated antigen 2)
3. IAA (insulin autoantibody)
4. GAD65 (glutamic acid decarboxylase 65)
5. ZnT8 (zinc transporter)

Question 11

What are some of the susceptibility genes associated with T1DM?

Answer 11

HLA e.g. DR3/4 - DR2/8

Insulin (VNTR)

PTPN22

IL2RA

CTLA-4

IFIH1

Question 12

What are some of the events which can precipitate T1DM?

Answer 12

Enteroviruses (esp. Coxsackie)

Rotavirus

Bacteria (e.g. myobacteria avium paraTB)

Environmental

• cow’s milk
• wheat proteins

Vitamin D deficiency

Insulin resistance (e.g. puberty)

?psychological stress

Question 13

In what ways can we predict if a patient has T1DM?

Answer 13

HLA genes
Auto-antibodies
First phase insulin response to glucose
T-cell function
Elevated lysophosphatyidylcholine
Reduced beta-cell mass (by PET)

Question 14

What other autoimmune diseases is T1DM associated with?

Answer 14

Thyroid disease (hypo and hyper)

Coeliac disease

Addison’s disease

Pernicious anaemia

Inflammatory bowel disease

Premature ovarian failure

Question 15

What is the most common type of mutation involved in monogenic (MODY) diabetes?

Answer 15

HNF-1alpha (60%)

Question 16

What 3 genetic mutations contribute to monogenic diabetes by affecting the release of transcription factors?

Answer 16

HNF-1alpha (60%)

HNF-4alpha (5%)

HNF-1beta (2%)

Question 17

What is the second most common mutation which causes monogenic diabetes?

Answer 17

Glucokinase (20%)

Question 18

What is the lease common cause of monogenic diabetes? What does this affect to cause diabetes?

Answer 18

Neonatal diabetes <1%

Affects the SUR potassium channel, therefore depolarisation cannot take place to cause the calcium influx required to release insulin