Type 1 Diabetes

Question 1

What is the ideal blood glucose level?

Answer 1

4.4-6.1

Question 2

Where is insulin produced?

Answer 2

By the beta cells in the Islets of Langerhans in the pancreas

Question 3

Which hormone has the opposite effects to insulin and where is it made?

Answer 3

Glucagon

- produced by the alpha cells in the Islets of Langerhans

Question 4

What is ketogenesis?

Answer 4

When there is insufficient glucose supply + glycogen stores are exhausted –> liver turns fatty acids into ketones to use as fuel

Question 5

What is the difference between the aetiology of type 1 and type 2 DM?

Answer 5

Type 1 –> pancreas doesn’t produce insulin

Type 2 –> reduced insulin sensitivity

Question 6

What are the symptoms of diabetes?

Answer 6

Polydipsia + polyuria
Weight loss (type 1)
Visual blurring from lens swelling
Genital thrush
Muscle cramps
Lethargy

T1DM often presents acutely e.g. in DKA

Question 7

What are the risk factors for T1DM?

Answer 7

Family history
HLA-DR3 + DR4
Other autoimmune conditions

Question 8

How is diabetes diagnosed?

Answer 8

If symptomatic, any of of:

• fasting glucose >/= 7
• random glucose >/= 11.1
• OGTT >/= 11.1
• HbA1c >/= 48 (6.5%)

If asymptomatic:
- repeat fasting glucose/OGTT/HbA1c on another day to confirm

Question 9

How is an OGTT carried out?

Answer 9

Patient fasts overnight

Measure glucose before and 2 hours after a glucose drink in the morning

Question 10

Following a diagnosis of diabetes mellitus, how do you know it’s type 1?

Answer 10

Largely clinical, supportive features:

• ketosis
• weight loss
• age < 50
• BMI < 25
• personal or family autoimmune history

If typical clinical features are absent, can check:

• GAD65 Ab (islet cell antibody)
• C-peptide (reduced in T1DM)

Question 11

Which other investigations should be done in a patient with newly diagnosed T1DM?

Answer 11

Urine albumin
HbA1c - re-check every 3-6 months
U&Es
Test for other AI disease: coeliac, TFTs

Question 12

What are the main components of managing T1DM?

Answer 12

Patient education essential –> DAFNE (dose adjustment for normal eating)
Lifelong SC insulin
Monitoring carbohydrate intake
Monitoring blood glucose
Monitoring for and managing complications

Question 13

When should newly diagnosed T1DM be started on insulin?

Answer 13

Same day –> referral to hospital diabetes team

Question 14

How often should blood glucose be checked?

Answer 14

At least 4 times a day

–> before each meal + before bed

Question 15

Where should insulin be injected, why?

Answer 15

Vary injection site across outer thigh + abdomen

- repeated injection into same site –> lipodystrophy

Question 16

What are the different types of insulin?

Answer 16

Rapid acting
Short acting
Intermediate acting
Long acting
Biphasic

Question 17

What is the onset and duration of rapid acting insulin? Give examples

Answer 17

Onset 5 mins
Take just before/after meal
Peaks 1-2 hours, lasts 4 hours

Lispro (Humalog)
Aspart (NovoRapid)

Question 18

What is the onset and duration of short acting insulin? Give examples

Answer 18

Onset 30 mins
Take 20 mins before meal
Peaks 3 hours, lasts 8 hours

Humulin S
Actrapid

Question 19

What is the onset and duration of intermediate acting insulin? Give examples

Answer 19

2 hour onset, peaks at 8 hours, lasts 12-16 hours

Isophane
Insulatard
Humulin I

Question 20

What is the onset and duration of long acting insulin? Give examples

Answer 20

1-2 hour onset, then constant up to 24 hours

Glargine (Lantus)
Levemir (Detemir)

Question 21

What is biphasic insulin? Give examples

Answer 21

Combination intermediate + rapid/short acting insulin

Novomix30 –> 30% rapid acting
Humalog50 –> 50% rapid acting

Question 22

How can the approximate total daily dose of insulin (TDDI) be calculate for children and adults?

Answer 22

Children –> 0.5 units/kg/day

Adults –> 0.3-0.5 units/kg/day

Question 23

What are the different regimens for insulin?

Answer 23

Once daily regimen
Twice daily regimen
Basal-bolus insulin regimen
Continuous SC insulin infusion

Question 24

When is once daily regimen used? What is involved?

Answer 24

Type 2 diabetes

Long or intermediate insulin at bedtime

Question 25

When is twice daily regimen used and what is involved?

Answer 25

Can be used in type 1 or 2

Biphasic insulin pre-breakfast (2/3) + pre-dinner (1/3)

Question 26

What are the side effects of twice daily insulin?

Answer 26

Nocturnal hypoglycaemia

Morning hyperglycaemia

Question 27

When is basal bolus insulin used and what is involved?

Answer 27

Aka multiple daily injections (MDI)
–> standard for T1DM

Basal injection: 1x long acting pre-bed
Bolus injections: 3x rapid acting pre-meal

Question 28

How is the bolus insulin dose calculated?

Answer 28

Number of units required for the carbs being eaten + number of units required to bring glucose back down to 4-8

Question 29

How is the basal insulin dose calculated?

Answer 29

TDDI divided by 2

the other half should be roughly split into 3 for the boluses

Question 30

What is continuous SC insulin infusion?

Answer 30

Aka insulin pump

Continuous rapid acting insulin + meal-time boluses activated by the patient

Question 31

What are the indications for continuous SC insulin infusion?

Answer 31

MDI failed e.g. multiple hypos
HbA1c > 69 despite high care
Children < 12 in MDI impractical