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Diagnosis of Diabetes

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Diabetes is reaching epidemic proportions as a consequence of the growing prevelance of obesity. It is also a disease which primary care frequently manages and is a large component of the GMS contract. However, it is not a purely homogeneous condition and is increasingly being sub-classified. This resource of 10 assessment questions is designed to test your knowledge on the diagnostic criteria developed for diabetes, the classification of diabetes and also introduce the concepts of a constellation of clinical features that represent the metabolic syndrome.

On completion of this resource, you should:

Have an improved understanding of the diagnostic criteria established for diagnosing diabetes

Improved understanding and ability to implement the appropriate diagnostic tests in a patient suspected of having diabetes.

Have a better understanding of the classification of diabetes and be able to identify patients with specific types of diabetes

Diabetes is reaching epidemic proportions as a consequence of the growing epidemic of obesity. It is also a disease which primary care frequently manages and is a large component of the GMS contract. However, it is not a purely homogeneous condition and is increasingly being sub-classified. This resource of 10 assessment questions is designed to test your knowledge on the diagnostic criteria developed for diabetes, the classification of diabetes and also introduce concepts of the metabolic syndrome.

Understand the diagnostic criteria established for diagnosing diabetes

Understand and be able to implement the appropriate diagnostic tests in a patient suspected of having diabetes.

Understand the classification of diabetes and be able to identify patients with the specific types of diabetes

Diabetes

A 52 year old male presents with a 6 month history of thirst and nocturia. He typically gets up 3 times per night to pass urine. He has gained approximately 15kg of weight over the last few years and informs you that he has a family history of diabetes as his mother and brother suffer from the condition. He is a non-smoker and drinks approximately 12 units of alcohol weekly. His weight is 114kg, with a BMI of 35kg/m

 and his waist circumference is 108cm. His blood pressure is 144/88 mmHg.Which of the following would be the most appropriate test to confirm the suspected diagnosis?

This man has symptoms of frequency of micturition and nocturia plus obesity with central adiposity and strong family history, which would all point towards a diagnosis of diabetes. His random glucose levels should be checked, a level of 11.1 mmol/l or higher would confirm the diagnosis of diabetes. The use of HbA1c as a diagnostic tool for diabetes is somewhat controversial and depends on the assay used. Urine dipstick analysis cannot be used to confirm a diagnosis of diabetes. The oral glucose tolerance test is a more complex approach to diagnosis and would require the patient to come in fasted and then have a glucose drink with samples measured at 0 mins and 2hrs.

Question 1

A 65 year old female attends clinic with a 3 month history of recurrent vaginal thrush. She has also noticed increasing thirst and needs to get up at least twice in the night to pass urine. Her weight is 99kg, with a BMI of 33.8 kg/m

 and her waist circumference is 98cm. She has a family history of diabetes with her father and mother both suffering from the condition. Her blood pressure is 150/88 mmHg. Her investigations reveal:

Which of the following is the likely diagnosis?

Given this woman's elevated random glucose and symptoms the correct diagnosis would be type 2 diabetes. Type 1 diabetes is unlikely given this woman's age, body type and family history. - type 1 being more common in young slim individuals.
Risk factors for type 2 diabetes are:

Question 2

A 65 year old male is being investigated for possible diabetes as he has presented with symptoms of weight gain and thirst. His fasting plasma glucose reveals the following:

This man has a fasting plasma glucose concentration of 6.5 mmol/l which is above the normal range but is below the threshold quoted to diagnose diabetes of 7 mmol/l. A figure of between 6-6.9 mmol/l on fasting plasma glucose indicates impaired fasting glucose. This should prompt further evaluation with an oral glucose tolerance test as potentially a diagnosis of diabetes could be confirmed in up to 30% of these cases and there would also be an increased future risk of developing diabetes.

Question 3

A 48 year old female attends clinic complaining of thirst and weight gain. There is a family history of weight problems and diabetes and she is concerned regarding her risk of developing diabetes. Her weight is 88 kg with a BMI of 31.2 kg/m

. Her blood pressure is 122/76 mmHg. Her results show:

This test result shows a normal fasting glucose and the patient should be reassured. No further testing for diabetes would be required at this stage but the patient should be concerned about the future risk of developing diabetes based on the family history and her obesity. Therefore the patient should be offered lifestyle advice on appropriate diet and exercise.

Question 4

A 25 year old male attends clinic complaining of weight loss, tiredness and thirst. He has noticed these symptoms for roughly 2 months and has lost approximately 6 kg in weight over this time. There is no other history of note and he has otherwise been fit and well. His weight is 72kg and his BMI is 22 kg/m

. His fasting glucose concentration is 14.5 mmol/l.Which of the following is the likely diagnosis?

This young man has diabetes as revealed by the fasting glucose above 7 mmol/l. Together with the symptoms of weight loss and thirst suggests that this is type 1 diabetes. Type 1 diabetes is typically seen in a younger age, is associated with weight loss (due to insulin deficiency) due to an autoimmune destruction of the beta cells of the pancreas. There typically is no family history of diabetes.
Patients with type 1 diabetes will always need treatment with insulin as the body destroys the cells of the pancreas which produce the hormone. Patients are prone to weight loss and ketoacidosis.

Question 5

These are the results of an oral glucose tolerance test that was performed on a 46 year old male who came to clinic with symptoms of thirst and associated weight gain.

The results of the oral glucose tolerance test reveal a normal fasting glucose, yet the 2 hr post OGTT glucose indicates diabetes (above 11.1 mmol/l).
The OGTT is used to assess the body's ability to metabolise sugar. The patient has their glucose levels measured before and at intervals after drinking a glucose drink.

People without diabetes should have a fasting level of under 6mmol/l and at 2 hours under 7.8mmol

People with impaired glucose tolerance have values between 6.0-7.0mmol/l at fasting and between 7.9-11mmol/l 2 hours after the drink

Diabetic individuals would expect to have a fasting value of above 7.0mmol and over 11mmol/l 2 hours after the glucose drink

Question 6

A 48 year old male with newly diagnosed type 2 diabetes attends clinic and has recently been started on metformin 500mg tds. Which of the following should be measured to assess his overall control?

The best method of assessing long term control is HbA1c. This refers to glycosylation of the haemoglobin molecule relating directly to the average glucose concentration over the lifecycle of the erythrocyte ie 3 months. Good control of HbA1c is reflected by a concentration below 7%.
Different levels can be expected for different groups of individuals:

An expected reading for a non diabetic would be between 4-5.9%

Diabetics are considered to have good control with a level of around 6.5-7%

Diabetics at a greater risk of hypoglycaemia may be given a slightly higher target of 7.5%

Question 7

A 55 year old female with type 2 diabetes attends clinic for annual review. She is taking metformin and gliclazide. Her HbA1c is 64 mmol/mol (8%) (normal range <42 mmol/l or 6%).What average plasma glucose concentration does this HbA1c actually reflect?

The HbA1c is used as a reflection of glycaemic control over a period of 3 months. In effect it reflects the average plasma glucose concentration over that period. However, the relationship is not specifically direct ie a level of 7%/53 mmol/mol HbA1c does not mean an average glucose of 7 mmol/l. Typically the average glucose is higher and this needs to be appreciated when considering control. Thus a HbA1c of 64 mmol/mol/8% approximates to an average glucose of 12 mmol/l.

Question 8

A 65 year old female presents with a four month history of weight loss, tiredness and thirst. There is no family history of diabetes and she has otherwise been well. She feels she has lost about 5 kg in weight over the last month. Her weight is 70kg and her BMI is 22 kg/m

. Her fasting plasma glucose concentration is 14.9 mmol/l (3.5-5.5). Which of the following is the likely diagnosis in this patient?

This older patient has been diagnosed with diabetes based on the symptoms of weight loss and the raised fasting plasma glucose concentration. However, this patient is thin with a BMI of 22 and has lost weight which suggests a relative insulin deficiency ie an autoimmune diabetes, but this is occurring later in adulthood. The diagnosis is LADA. This diagnosis should be considered in patients presenting in this fashion and it is an important diagnosis to make as treatment would entail either a trial of a sulphonylurea or indeed insulin.
LADA is an autoimmune condition with many similarities to type 1 diabetes, although the destruction of pancreatic cells tends to be slower than in type 1. The cardiovascular risks for LADA patients are similar to those with type 2 diabetes. The same can be said for rates of microvascular complication such as retinopathy and neuropathy. Management involves trying to preserve beta cell function. Insulin, metformin and thiazolidinediones are medications to be considered.

Question 9

A 55 year old female with a five year history of type 2 diabetes which has been treated with diet alone is noted to have a HbA1c of 66 mmol/mol/8.2% (normal range less than 42 mmol/mol or 6%). She has a BMI of 32.3 kg/m

 and a waist circumference of 96cm. As her glycaemic control is not optimised, her GP has commenced her on metformin 500mg tds. When would you next recall this patient to have her HbA1c checked?

This woman with type 2 diabetes has noted a gradual deterioration in glycaemic control as reflected by a HbA1c of 64mmol/mol or 8.2%. Therefore, she has been commenced on metformin together with lifestyle modification in an effort to improve her glycaemic control. As HbA1c is a reflection of the glycosylation of the haemoglobin molecule contained within the red blood cell, it provides a far better perspective on glycaemic control than random glucose. As we analyse the haemoglobin molecule within the red cell, we need to bear in mind that the lifespan of the red cell is 90 days. Hence the HbA1c reflects the level of glycaemia over this period. So, the appropriate timeframe to repeat a HbA1c following intervention is 3 months.

Diagnosis of Diabetes

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