Diabetes basic principles

Question 1

What is diabetes mellitus

Answer 1

An elevation of blood glucose above a diagnostic threshold

Question 2

Thresholds for diagnosing diabetes

Answer 2

Set by risk of retinopathy

Question 3

Fasting Plasma Glucose

Answer 3

126mg/dl = 7mmol/L

Question 4

2 hr plasma glucose

Answer 4

200mg/dl = 11.1 mmol/L

Question 5

HbA1c

Answer 5

5.8% = 48 mmol/mol

Question 6

Gestational diabetes

Answer 6

Threshold levels are NOT set by retinopathy risk but rather by risk to the foetus/neonate

Question 7

Diagnosing diabetes

Answer 7

If asymptomatic a repeat confirmatory test is required

Random or 2 hr (after 75g Oral Glucose) glucose >=11.1.
OR
A fasting glucose of >=7.0mmol/L
OR
An HbA1c >= 48mmol/mol

Question 8

Glucagon

Answer 8

from alpha cells in pancreatic Islet

Question 9

Insulin

Answer 9

from beta-cells in the pancreatic islet

Question 10

C-peptide

Answer 10

useful way to measure ‘endogenous’ insulin secretion

co-secreted with insulin and is not part of injected insulin – so if c-peptide is present in the blood it must be coming from the person’s beta-cells

Question 11

2 causes of diabetes

Answer 11

• disorder of insulin secretion (beta cells)

-disorders of insulin action

Question 12

Disorders insulin secretion

Answer 12

• type 1 diabetes

-genetic disorder

-pancreatic diseases

Question 13

Genetic disorders

Answer 13

MODY
Neonatal diabetes

Question 14

Pancreatic diseases (7)

Answer 14

alcohol & chronic pancreatitis

acute pancreatitis

Pancreatectomy

pancreatic cancer

cystic fibrosis

haemachromatosis

Question 15

Disorders insulin action (4)

Answer 15

Pure disorders - rare and mostly genetic

Insulin resistance

Endocrinopathies

Steroid use

Question 16

Pure disorders (5)

Answer 16

Donohue Syndrome

Rabson-Mendenhall Syndrome

Familial Partial Lipodystrophy

Congenital Lipoatrophy

Acquired Lipoatrophy

Question 17

Insulin resistance (3)

Answer 17

Feature of -
Obesity

Type 2 Diabetes

NAFLD

Question 18

Endocrinopathies (4)

Answer 18

Cushings Syndrome

Acromegaly

Phaeochromocytoma

Glucagonoma

Question 19

Steroid use

Answer 19

i.e. exogenous glucocorticoids

Question 20

Type 1 Diabetes (3)

Answer 20

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

usually children and young adults, but occurs at a similar rate at all ages

Most – up to 95% - have pancreatic autoantibodies in the blood at diagnosis

Question 21

Type 2 Diabetes (4)

Answer 21

predominantly insulin resistance with relative insulin deficiency to predominantly an insulin secretory defect with insulin resistance

90-95% of diabetes

Autoimmune destruction of the beta-cell does not occur

Patients do not have any other known cause for their diabetes

Question 22

Presentation (8)

Answer 22

Often asymptomatic – esp. Type 2 diabetes

Symptoms of
-high blood glucose
-Polyuria
-Thirst and polydipsia
-Blurred vision
-Genital Thrush
-Fatigue
-Weight loss

Question 23

Symptoms/signs of complications (rarely)

Answer 23

-Loss of vision/retinal bleed or retinal changes found by optician

Question 24

Why treat diabetes

Answer 24

To prevent the acute symptoms and life-threatening illness

Question 25

Microvascular Complications (4)

Answer 25

driven by chronic hyperglycaemia

• Retinopathy
  -Neuropathy
  -Nephropathy

Question 26

Macrovascular complications (6)

Answer 26

due to hyperglycaemia, high blood pressure and dyslipidemia

-Myocardial Infarction/ACS
-Stroke
-Peripheral Vascular Disease

Question 27

How is diabetes monitored?

Answer 27

using HbA1c

Question 28

HbA1c- what is it? (4)

Answer 28

Glycated Haemoglobin
- Haemoglobin exposed to glucose becomes glycated

• The amount of glycation is proportional to the glucose
• As a red blood cell survives for ~90 days the HbA1c gives a measure of glucose exposure over the last 90 days
• Caution in conditions of increased or reduced red cell turnover e.g. haemolytic anaemia; Haemoglobinopathies may give spurious results