DM: Classification, Dx and Causes

Question 1

Definition

Answer 1

Multisystem disorder due to an absolute or relative lack of endogenous insulin → metabolic and vascular complications.

Question 2

Type 1

Answer 2

Path: autoimmune destruction of β-cells → absolute insulin deficiency. Age: usually starts before puberty Presentation: polyuria, polydipsia, ↓wt., DKA Genetics: concordance only 30% in MZs Assoc.: HLA-D3 and –D4, other AI disease Abs: anti-islet, anti-GAD

Question 3

Type 2

Answer 3

Path: insulin resistance and β-cell dysfunction → relative insulin deficiency Age: usually older patients Presentation: polyuria, polydipsia, complications Genetics: concordance 80% in MZs Assoc.: obesity, ↓exercise, calorie and EtOH excess

Question 4

Diagnosing - symptomatic

Answer 4

polyuria, polydipsia, unexplained weight loss, visual blurring, genital thrush, lethargy

↑ plasma venous glucose detected once

Fasting ≥7mM Random ≥11.1mM or >6.5% HbA1c

Question 5

Diagnosing - asymptomatic

Answer 5

↑ venous glucose on 2 separate occasions Or, 2h OGTT ≥ 11.1mM or > 6.5% HbA1c

Question 6

When to use glucose testing

Answer 6

Borderline fasting or random glucose measurements Pregnancy

Question 7

Ix if diagnosis is uncertain? Results?

Answer 7

C-peptide will be low in individuals with type 1 diabetes mellitus (as the pancreas is not making enough insulin precursor, which breaks down to form C-peptide and insulin) , and normal or high in individuals with type 2 mellitus.

Question 8

Glucose tolerence test results

Answer 8

Question 9

Secondary causes of DM

Answer 9

Drugs: steroids, anti-HIV, atypical neuroletics, thiazides

Pancreatic: CF, chronic pancreatitis, HH, pancreatic Ca

Endo: Phaeo, Cushings, Acromegaly, T4

Other: glycogen storage diseases

Question 10

What is metabolic syndrome?

Answer 10

Central obesity (bmi >30, or ↑ waist circ)

plus 2 of bp ≥130/85, triglycerides ≥1.7mmol/L, hdl ≤ 1.03♂/1.29♀mmol/L, fasting glucose ≥5.6mmol/L or dm

Question 11

When should HbA1c not be used for diagnosis?

Answer 11

Children and young people (younger than 18 years of age).

Pregnant women or women who are two months postpartum.

People with symptoms of diabetes for less than 2 months.

People at high diabetes risk who are acutely ill.

People taking medication that may cause hyperglycaemia (for example corticosteroids).

People with acute pancreatic damage, including pancreatic surgery.

People with end-stage chronic kidney disease.

People with HIV infection.

Question 12

HbA1c should be interpreted with caution:

Answer 12

Abnormal haemoglobin.

Anaemia (any cause).

Altered red cell lifespan (for example post-splenectomy).

A recent blood transfusion.

Question 13

What is impaired fasting glucose

Answer 13

A fasting glucose greater than or equal to 6.1 but less than 7.0 mmol/l implies impaired fasting glucose (IFG)

due to hepatic insulin resistance

Question 14

What is impaired glucose tolerance

Answer 14

Impaired glucose tolerance (IGT) is defined as fasting plasma glucose less than 7.0 mmol/l and OGTT 2-hour value greater than or equal to 7.8 mmol/l but less than 11.1 mmol/l

due to muscle insulin resistance

patients with IGT are more likely to develop T2DM and cardiovascular disease than patients with IFG

Question 15

What is ancothosis nigricans a sign of

Answer 15

Acanthosis nigricans is a sign of insulin resistance, also associated with type 2 diabetes mellitus.

Also seen in gastric lymphoma

Question 16

What is LADA

Answer 16

disorder in which, despite the presence of islet antibodies at diagnosis of diabetes, the progression of autoimmune -cell failure is slow.

In contrast to type 2 diabetes, patients are typically younger and without an increased body habitus. In contrast to type 1 diabetes, insulin is not usually required in the early stages of the disease.

Diagnosis may be aided through a Glutamic Acid Decarboxylase (GAD) Autoantibodies test and evidence of other autoimmune diseases.