Diabetes- Overview

Question 1

Diabetes Mellitus

Answer 1

Elevation of blood glucose above a diagnostic threshold

Question 2

Threshold for diagnosis

Answer 2

Based on risk of developing diabetic retinopathy

Fasting Plasma Glucose >7mmol/l

2hr plasma glucose > 11.1 mmol/L

Random blood glucose >11.1 mol/L

HbA1c > 48mmol/mol

Question 3

Gestational Diabetes Criteria

Answer 3

Based on risk to foetus

Fasting plasma glucose >5.1 mol/L

2hr plasma glucose >8.5 mol/L

Question 4

Insulin

Answer 4

Secreted from beta-cells in the pancreatic islet

Released in response to increased blood glucose level

Question 5

Glucagon

Answer 5

Secreted from alpha-cells in the pancreatic islet

Released in response to low blood glucose levels

Question 6

C-peptide

Answer 6

Co-secreted with insulin

Can be used to measure endogenous insulin secretion

Question 7

Diabetes Aetiology (Type 1 and Type 2)

Answer 7

Type 1
- Disorder of insulin secretion

Type 2
- Mixed ranging from predominant beta-cell deficiency to predominant insulin resistance

Pancreatic disease (esp chronic pancreatitis such as from alcoholism) can lead to disorder of insulin secretion

Question 8

Type 1 Diabetes Mellitus

Answer 8

Autoimmune destruction of the pancreatic beta cells resulting in beta-cell deficiency

Occurs at a similar rate at all ages

Most (>95%) have pancreatic autoantibodies in the blood

Question 9

Type 2 Diabetes Mellitus

Answer 9

Ranges from predominantly insulin resistance with relative insulin resistance to predominantly an insulin secretory defect with insulin resistance
– diagnosis of exclusion

Patients do NOT have any other causes of diabetes

Autoimmune destruction of beta-cells does NOT occur

Question 10

Diabetes Presentation

Answer 10

often asymptomatic

High blood glucose

• Polyuria
• Thirst and polydipsia
• Blurred vision
• Genital thrush
• fatigue
• weight loss

Question 11

microvascular complications

Answer 11

largely driven by chronic hyperglycaemia

• Retinopathy
• nephropathy
• neuropathy

Question 12

microvascular changes

Answer 12

Increased risk in all diabetes

MI/ACS
Stroke
Peripheral vascular disease

Question 13

HbA1c

Answer 13

Glycated haemoglobin

Haemoglobin exposed to glucose becomes glaciated. Amount of glycation is proportional to the glucose.

As a RBC survives ~90days, the HbA1c gives a measure of glucose over last 90 days.

CAUTION in conditions of increased or reduced red cell turnover (e.g. haemolytic anaemia)