Laboratory Tests in Diabetes

Question 1

why do we use lab tests in diagnosis?

Answer 1

Confirmation or rejection of clinical diagnosis

Question 2

why do we use lab tests in monitoring?

Answer 2

Natural history or response to treatment

Question 3

why do we use lab tests in prognosis?

Answer 3

Prediction of course or outcome of the disease

Question 4

what do we use lab tests in screening?

Answer 4

Detection of sub-clinical disease

Question 5

what are the stages between a clinical question and a biochemical answer?

Answer 5

Question 6

what is precision versus accuracy?

Answer 6

Question 7

what is a reference range?

Answer 7

Question 8

how is diagnosis of diabetes made?

Answer 8

Random venous plasma glucose >11.1mmol/L
Fasting plasma glucose >7.0mmol/L

2 hour plasma glucose >11.1mmol/L in OGTT

HbA1c >48mmol/mol (Type 2 Diabetes only)

If asymptomatic, requires confirmation by repeat testing on another day

Question 9

with HbA1-c what are we monitoring?

Answer 9

Question 10

when do we not use HbA1-c to diagnose diabetes?

Answer 10

Children and young people

Suspected Type 1 diabetes

Symptoms <2 months - not time for hba1c to reflect

High risk patients who are acutely ill

Patients taking medication that may cause rapid glucose rise (e.g. steroids)

Acute pancreatic damage
Pregnancy
Presence of genetic, haematological or illness-related factors that affect HbA1c and its measurement

Question 11

how are acute presentations of diabetes monitored?

Answer 11

urine testing - glycosuria, ketonuria

GLUCOSE METER-MEASUREMENT OF
CAPILLARY BLOOD GLUCOSE

Question 12

13 year old female with known type 1 diabetes mellitus admitted to A&E because of drowsiness and vomiting, what tests would you do?

Answer 12

POCT Testing - A Point of Care finger prick test in A&E showed blood glucose of 20 mmol/L.

The FY2 was going to give her some more insulin but decided to confirm the result by sending a blood sample to the lab.

Question 13

if a result came back from POCT high but low from blood glucose what may this mean?

Answer 13

Contamination when checking POC glucose

Question 14

21 year old student - thirst, polyuria and weight loss over the last two months; became unwell with flu-like symptoms and began vomiting.

Urinalysis-
Glucose ++++
Ketones ++

Dehydrated, tachypnoeic and generalised abdominal tenderness, admitted to the surgical ward on 40% O2

what is the likely diagnosis?

Answer 14

Diabetic ketoacidosis

Question 15

what would biochemistry results show in ketoacidosis?

Answer 15

Question 16

A 21 year old woman with diabetes
mellitus was admitted to the medical
ward for the investigation of recurrent
hypoglycaemic episodes despite her insulin dose being reduced.

what is the most likely diagnosis, how would you reach this?

Answer 16

do an insulin measurement - Insulin 165 mU/L (<13), C-Peptide undetectable

Insulin administration

Question 17

what would Factitious hypoglycaemia show?

Answer 17

high insulin levels in absence of elevated C-peptide concentrations.

Question 18

what would insulinoma show?

Answer 18

elevated C-peptide level indicative of insulin-secreting tumour.

Question 19

what are examples of macrovascular diseases?

Answer 19

TIA, angina, MI, cardiac failure

Question 20

what are examples of microvascular diseases?

Answer 20

diabetic retinopathy

Question 21

what are examples of neuropathy?

Answer 21

erectile dysfunction

Question 22

Biochemical Measurements in Diabetes: Chronic?

Answer 22

Glucose (self-monitoring of blood glucose)

HbA1c (Glycaemic control)

Urine Albumin/creatinine ratio (Diabetic renal disease - Microvascular screening)

Lipids (Macrovascular screening)

Question 23

HBA1C-GLYCAEMIC CONTROL, what is the risks of complications if poor control progresses?

Answer 23

Question 24

64 year old lady with Type 2 Diabetes Mellitus

HbA1c 30mmol/mol
(37mmol/mol five months previously).

Home blood glucose monitoring – glucose results consistently 17-18mmol/L

LFTs –
ALT 65 IU/L (<45)
BILIRUBIN 45umol/L (<22)
ALK PHOS 72 IU/L (25-110)

what is the most likely diagnosis?

Answer 24

Haemolytic anaemia

Question 25

A 56 year old female with a 12 year history of Type 2 Diabetes was found to have a urine albumin/creatinine ratio of 32 mg/mmol (female reference interval <3.5 mg/mmol)

what is the likely diagnosis?

Answer 25

chronic kidney disease

Question 26

which of the following is a potential cause of raised ACR

Answer 26

Urinary tract infection

Orthostatic proteinuria

Diabetic kidney disease

Angiotensin converting enzyme inhibitors

Question 27

what should be used to screen for diabetic kidney disease?

Answer 27

ACR