7: Pathophysiology of T1 DM

Question 1

Type 1 diabetes is a state of (relative / absolute) insulin deficiency.

Answer 1

absolute insulin deficiency

Question 2

In all likelihood, Type 1 diabetes is an autoimmune disease with ___ and ___ causes.

Answer 2

genetic and environmental causes

Question 3

What are the diagnostic criteria for Type 1 diabetes?

Answer 3

Fasting glucose > 7.0 mmol/L

Random glucose > 11.1 mmol/L

and symptoms:

polyuria

polydipsia

weight loss

fatigue

+/- blurred vision, UTI

Question 4

What are some possible triggers for T1 DM?

Answer 4

Viral infection

Maternal factors

Weight gain (adiposity??)

Question 5

If you’re unsure whether a person has Type 1 or Type 2 diabetes and you’ve tested glucose, what other two tests could you carry out?

Answer 5

Islet autoantibody test

C-peptide levels

Question 6

What happens to beta cells histologically in Type 1 diabetes?

Answer 6

Insulitis

Infiltration by lymphocytes

Destruction of cell

Question 7

What genes mutate to cause T1 DM?

Answer 7

HLA-DR3/DR4

To add to the list:

Coeliac disease - HLA-DQ2 or HLA-DQ8

Spondyloarthropathies - HLA-B27

Question 8

What specific autoantibodies cause T1 DM?

Answer 8

Islet cell antibodies (ICA)

Question 9

At what point is the onset of T1 DM irreversible?

Answer 9

Loss of first phase insulin response

Question 10

What are the classic symptoms of diabetes?

Answer 10

Polyuria

Polydipsia

Weight loss

Fatigue

+/- Symptoms of complications - blurred vision, neuropathy, glycosuria, DKA, CVD

Question 11

People suffering from DKA will have what positive sign?

Answer 11

Ketonaemia

Question 12

How is Type 1 diabetes managed?

Answer 12

Blood glucose and ketone monitoring

Insulin

Question 13

What insulin plan are patients with Type 1 diabetes put on?

Answer 13

Basal-bolus

They take long-acting insulin before bed to last them throughout the night (and day), plus fast-acting insulin matched to their meals

Question 14

What is the ideal HbA1c level in patients with Type 1 diabetes?

Answer 14

< 48 mmol/mol

Question 15

In the management of most patients with Type 1 diabetes, you aim for an HbA1c level of 48 - ___ mmol/mol.

Answer 15

48 - 58 mmol/mol

Question 16

What is assessed at review of patients with Type 1 diabetes?

Answer 16

Weight

BP

FBC - HbA1c, renal function, lipids

Retinal screening

Foot assessment

Question 17

Type 1 diabetes is most common in (young / older) people.

Answer 17

young people

Question 18

What congenital disease, causing pancreatic damage, predisposes patients to developing secondary diabetes?

Answer 18

Cystic fibrosis

Question 19

What are some types of diabetes you’re likely to see in young people?

Answer 19

Type 1 diabetes

Monogenic diabetes / MODY (which covers neonatal diabetes)

LADA (late-onset T1 diabetes)

Secondary diabetes (to something like cystic fibrosis)

Question 20

Insulin secretion is ___.

Answer 20

biphasic

Question 21

A male patient develops diabetes at the age of 30, is lean and positive for Islet cell antibodies. He has Crohn’s disease, doesn’t require insulin but can’t control his diabetes very well with drugs.

What does he likely have?

Answer 21

LADA

Late-onset Type 1 diabetes

Question 22

What is a rare autosomal recessive disease which causes:

Diabetes insipidus

Diabetes mellitus

Optic atrophy

and deafness?

Answer 22

Wolfram syndrome

Question 23

Out of Type 1 diabetes, LADA, MODY and Type 2, which is most associated with ketonaemia?

Answer 23

Type 1 diabetes

Question 24

What are some autoimmune diseases associated with Type 1 diabetes?

Answer 24

Thyroid disease

Coeliac disease

Pernicious anaemia (parietal cells destroyed leading to Vit B12 insufficiency)

Addison’s disease (hypoadrenalism)

Vitiligo