Diabetes: diagnosis, epidemiology + complications

Question 1

Clinical diagnosis criteria for type 1 diabetes

Answer 1

hyperglycaemia +

• ketosis
• rapid weight loss
• age onset <50y
• BMI <25
• personal and/or family history of autoimmune disease

Question 2

Diabetes complications

Answer 2

retinopathy
nephropathy
foot problems
circulation problems
pregnancy
personal impact + quality of life

Question 3

Vascular complications of type 2 diabetes at time of diagnosis

Answer 3

retinopathy
nephropathy
erectile dysfunction
ischaemic skin changes
abnormal vibration threshold
cerebrovascular disease
abnormal ECG
hypertension
intermittent claudication
absent foot pulses

Question 4

What causes type 1 diabetes?

Answer 4

destruction of pancreatic beta cells leading to absolute insulin deficiency

Question 5

What are type 1A and type 1B diabetes?

Answer 5

1A = autoimmune destruction of pancreatic beta cells

1B = patients with absolute insulin deficiency with no evidence of autoimmunity or other known cause of beta cell destruction

Question 6

What autoantibodies can be found in T1DM?

Answer 6

Glutamic acid decarboxylase (GAD)
Islet antigen 2 (IA-2)
Insulin (IAA)
ZnT8

Question 7

What are some triggers of T1DM?

Answer 7

chemicals
viruses (mumps, rubella, CMV, enteroviruses)
bacteria
intrauterine factors (pre-eclampsia, maternal rubella, caesarean section, birth weight)
diet (vit D deficiency, milk protein)
stress

Question 8

Clinical presentation of T1DM?

Answer 8

acute onset with classical osmotic symptoms
weight loss predominates (catabolism of protein and fat resulting from profound insulin deficiency)

5-10% present with DKA

Question 9

What causes T2DM?

Answer 9

peripheral insulin resistance with a relative (rather than absolute) deficiency in insulin secretion

• decreased glucose uptake in muscle, fat and the liver
• excess hepatic glucose output
• a pancreatic beta-cell insulin secretory deficit

Question 10

Factors that affect insulin secretion and action

Answer 10

body weight
level of physical activity
smoking
heavy alcohol consumption
genetic predisposition
gene-environment interaction
epigenetics
gestational diabetes mellitus

Question 11

T2DM clinical presentation

Answer 11

onset of disease is often slow, diagnosis is often delayed - many patients present with complications of chronic hyperglycaemia

some cases are detected incidentally

Question 12

What is pre-diabetes and what is the threshold?

Answer 12

impaired fasting glycaemia
glucose 6-7 mmol/L

Question 13

What are the WHO criteria for diabetes diagnosis?

Answer 13

in presence of symptoms:
- random plasma glucose >11.1 mmol/L
OR
- fasting plasma glucose >7 mmol/L
OR
- 2 hour plasma glucose >11.1 mmol/L 2 hours post 75g OGTT

in asymptomatic individuals, at least one of the above criteria fulfilled on 2 separate occasions

Question 14

What is the WHO HbA1C criteria for diabetes diagnosis and who can it be used for?

Answer 14

HbA1C > 48 mmol/mol (6.5%) with symptoms and plasma glucose >11.1 mmol/L

OR

HbA1C > 48 mmol/mol (6.5%) in asymptomatic patient

not to use in children and young people, T1DM, symptoms within 2 months, pregnancy, drugs causing hyperglycaemia or blood conditions affecting Hb

Question 15

How is HbA1C formed and what does it reflect?

Answer 15

formed by glycation of haemoglobin as it is exposed to plasma glucose

reflects average plasma glucose over the previous 8-12 weeks

Question 16

When is HbA1C unreliable?

Answer 16

pregnancy
symptom onset within 2 months
anaemia and haemoglobinopathies
children and young people
acutely ill

Question 17

How is an oral glucose tolerance test carried out?

Answer 17

overnight fast (>8 hours)
fasting plasma glucose
75g anhydrous glucose to drink
2nd blood sample 2 hours later

7.8-11 mmol/L = pre-diabetes
>11 mmol/L = diabetes

Question 18

When is oral glucose tolerance test used?

Answer 18

used for gestational diabetes and where HbA1C is unreliable

Question 19

4 main aims of diabetes management

Answer 19

minimisation of long-term complications
minimisation and prevention of hyperglycaemic diabetic emergencies (DKA/HHS)
minimisation of osmotic symptoms
avoidance of iatrogenic side-effects eg. hypoglycaemia

Question 20

Macrovascular diabetes complications

Answer 20

coronary artery disease
cerebrovascular disease
peripheral vascular disease

Question 21

Microvascular diabetes complications

Answer 21

nephropathy
retinopathy
autonomic neuropathy
peripheral sensory neuropathy
mononeuropathy

Question 22

How does hyperglycaemia accelerate atherosclerosis?

Answer 22

increased endothelial permeability

increased presence of reactive oxygen species leading to increased oxidation of LDL

upregulation of cytokines leading to increased proliferation of smooth muscle in plaques

Question 23

Definition of diabetic nephropathy

Answer 23

presence of dipstick positive proteinuria in a patient with diabetes
(equates to urinary albumin conc 300mg/L or greater)

Question 24

Distribution of diabetic neuropathy

Answer 24

glove and stocking
distal symmetrical sensorimotor polyneuropathy

Question 25

What are 2 of the first features found in diabetic peripheral neuropathy?

Answer 25

absent ankle jerks
decreased vibration sensation