FreeStyle Blood Glucose Meters

IT HAS BEEN PREDICTED THAT BY 2020 MORE THAN 175,000 PEOPLE AGED 45+ YEARS IN IRELAND WILL HAVE DIABETES.¹

This is an alarming thought since the complications of diabetes – such as diabetic ketoacidosis (DKA), kidney failure, blindness, heart disease, stroke and nerve damage – have a significant cost, both an emotional cost to the individual and their family and a financial cost to the Health Service Executive (HSE).¹ Monitoring diabetes is a crucial part of preventing some of these possible complications. There are a range of tests that can be performed to monitor the health of a person with diabetes, including blood glucose, glycated haemoglobin, ketone levels, blood pressure and blood fat levels.²

This module will focus primarily on the monitoring and management of blood glucose and blood ketone levels.

 THE TRIANGLE OF DIABETES CARE

Patient self-monitoring of glucose can lead to better patient outcomes through the trio of goals of the triangle of diabetes care. According to National Institute for Health and Care Excellence (NICE) guidance, self-monitoring of plasma glucose should be available:¹⁴

• To those on insulin treatment
• To those on oral glucose-lowering medications to provide information on hypoglycaemia
• To assess changes in glucose control resulting from medications and lifestyle changes
• To monitor changes during intercurrent illness
• To ensure safety during activities, including driving

As part of the day-to-day routine, glucose monitoring can help with necessary lifestyle and treatment choices, and help patients monitor for symptoms of hypo- or hyperglycaemia. Recording trends in glucose patterns can also be beneficial to help with diabetic patient management.

The main reason to define diabetes is to identify those patients who have a high risk of diabetes complications and may benefit from treatment.¹⁵ The World Health Organization recommends the measurement of glycated haemoglobin (HbA1c) for the diagnosis of diabetes.¹⁶ By the time diabetes is diagnosed, half of the people with Type 2 diabetes show signs of complications.¹⁷ Aside from HbA1c levels, it is important to consider which factors may be responsible for the complications of diabetes. One of these factors is glycaemic variability.

Introduced nearly 30 years ago, HbA1c is the classic marker of long-term glycaemic status and has been regarded as having ‘strong predictive value for diabetes complications.’¹ There is, however, a plethora of emerging evidence that HbA1c levels are inadequate for determining the likelihood of developing diabetes-related complications.² This has led to the concept of glycaemic variability.

Glycaemic variability, very simply put, is the excursion of blood glucose from low to high and back again. Glycaemic variability can also be referred to as the 'quality' of HbA1c. The steadier the blood glucose levels, the higher the quality of HbA1c and tight long-term glucose control can delay the onset of diabetes-related complications.7 Glycaemic variability, in addition to glycaemic level, is an important factor that increases metabolic stress and mortality in patients in acute states.^3,4

Most therapies used to treat diabetes are assessed primarily on their ability to reduce HbA1c. However, since HbA1c levels are a measure of long-term glycaemia, by definition they are not designed to capture the rate and amplitude of blood glucose fluctuations.⁵ In some patients, e.g. those who do not self-monitor their glucose, HbA1c is also the main way their everyday glucose control is assessed. The presence of marked fluctuations in glucose may therefore remain hidden.

HbA1c measurements alone cannot sufficiently define the metabolic status and risk level in patients with diabetes. Both long-term glucose level abnormality and short-term glucose variability, in terms of both high and low blood glucose levels, affect diabetes-related complications. In fact, fluctuating glucose levels can be more harmful than sustained chronic hyperglycaemia for both endothelial function and oxidative stress. These are two key players in the development and progression of diabetic-related cardiovascular complications.³

In a 24-hour period, glucose levels fluctuate in people with or without diabetes. The factors that contribute to these fluctuations and advice that could be useful to an adult with diabetes to help minimise these fluctuations are briefly discussed in the table below and continued overleaf:

FOOD:

The carbohydrate content and the glycaemic index (GI) in the food, when it was eaten with relation to medication and how much was eaten affects glucose levels.

TIPS:

• Being consistent with food habits
• Spreading out the carbs
• Choosing foods with a low GI
• Coordinating meals with medication

EXERCISE:

Exercise can help the body utilise glucose and improves its response to insulin. From strenuous workouts to light activities, such as housework and gardening, exercise can cause blood glucose levels to fall.

TIPS:

• Consulting with a healthcare professional (HCP) before starting any vigorous exercise regime
• Coordinating insulin doses/medication with an exercise routine
• Keeping hydrated by drinking plenty of sugar-free fluids
• Monitoring sugar levels in patients on glucose control therapy before, during and after exercising
• Stopping if warning signs like shortness of breath or dizziness are experienced

MEDICATION:

While antidiabetic medications are prescribed to lower blood glucose levels, effectiveness of these medications depends on the timing, strength, frequency of the dose and patient concordance. Other medications, e.g. over-the-counter cold medicines, sometimes contain sugar or alcohol that could increase glucose levels.

TIPS:

• Reporting any problems experienced to an HCP
• Coordinating medication schedules with exercise routines and meals with help from an HCP
• Ensuring good concordance with prescribed medication schedules
• Storing medication appropriately according to the specific information in the patient leaflet and noting expiry dates

ILLNESS:

Infections can cause blood glucose levels to rise, even if the normal diet is not being consumed.

TIPS:

• Planning ahead to agree a ‘sick-day’ plan with an HCP regarding medications and dosage
• Trying to eat and drink as normally as is possible
• Notifying an HCP about severe vomiting, respiratory symptoms and high blood glucose
• Monitoring blood glucose levels if appropriate

STRESS:

Emotions such as anxiety, stress (mental or physical) or inadequate sleep can cause elevated blood glucose levels as a result of adrenaline release. Additionally, an adult with diabetes is less likely to stick to an eating plan, exercise regime and medication schedule when stressed. All this can cause glucose levels to go awry.

TIPS:

• Looking for patterns to identify what is causing stress and its relation to blood glucose levels
• Taking control by prioritising one’s health
• Learning relaxation techniques and using exercise to control anxiety
• Talk to other people about how you are feeling, e.g. family, friends, an HCP or talking therapies

ALCOHOL:

Alcohol can cause glucose levels to fall and also impair judgement about eating and medication. Additionally, dancing can be unexpected vigorous exercise and that is not often taken into account while planning medication doses.

TIPS:

• Agreeing with an HCP what quantities of alcohol would be suitable for an individual – following HSE guidance¹
• Choosing drinks wisely (in terms of the sugar content) and knowing the percentage of alcohol in drinks
• Tallying additional calories that alcohol contributes and avoiding mixing alcohol with sugary drinks or juice
• Going out with someone who can look out for the person with diabetes

PREGNANCY AND MENSTRUATION::

Hormone surges during pregnancy and menstruation can cause blood glucose swings.

TIPS:

• Monitoring blood glucose levels
  – It is important to discuss with your HCP if you are planning to become pregnant or you think you may be pregnant
• Talking to your HCP about insulin dose adjustments during menses

IN PRACTICE, GLYCAEMIC VARIABILITY HAS TWO MAIN MANIFESTATIONS:

• Hypoglycaemia – (blood glucose less than 4.0 mmol/L)¹ has been identified as the ‘Achilles’ heel of diabetes treatment’² and it presents a major barrier to satisfactory long-term glycaemic control.¹ Glucose-reducing therapies can cause acute lowering of blood glucose levels, potentially leading to severe hypoglycaemia.²
• Hyperglycaemia and postprandial glucose (PPG) excursions – PPG excursions appear to have an impact not only by the value they reach, but also the duration of their peak value. Postprandial hyperglycaemia has been established as a ‘direct and independent risk factor’ for the development of cardiovascular disease (CVD) in Type 2 diabetes.^3,4 ‘Hyperglycaemic spikes’ – rapid postprandial increase in blood glucose concentrations – appear to be more significant than elevations in fasting plasma glucose (FPG). Therefore, it is suggested that therapeutic targets must be aimed at reducing postprandial blood glucose excursions.

MANAGEMENT – HOW DO WE AVOID HYPOGLYCAEMIA?

• Avoiding hypoglycaemia is a key aim in the management of diabetes and, as mentioned above, hypoglycaemia remains a major challenge in achieving optimal glycaemic control. General strategies to prevent hypoglycaemia can include:⁵ – Diabetes self-management (supported by education and empowerment)
  – Self-monitoring of blood glucose or continuous glucose sensing
  – Flexible and appropriate insulin or other drug regimens
  – Glycaemic goals that are individualised to the patient
  – Consideration of known risk factors of hypoglycaemia
  – Professional support and guidance, which can also play an important role in the early detection and management of both short and long term complications

MANAGEMENT – HOW DO WE LIMIT GLYCAEMIC VARIABILITY?

The strategies to reduce glycaemic variability are simple; however, patients can sometimes find it difficult to fit these into their everyday lives. Therefore, it is important to bear in mind that it is not desirable or feasible that complete glucose fluctuations be minimised, it is only the extreme values (peaks of high and low) that need tackling.

• Practical strategies – because there may be a few differences in the reasons behind PPG excursions in Type 1 and Type 2 diabetes, the practical approach to managing them may also differ. Points to consider include:
  – How behaviours and lifestyle can help reduce glycaemic variability and avoid hypoglycaemia
  – Why glucose values go high postprandially and how these excursions could be controlled
  – How recording and monitoring trends in glucose can help identify and prevent glycaemic variability and hypoglycaemia
• Pharmacological therapies – therapeutic agents that reduce PPG excursions, e.g. glucagon-like peptide-1 agonists and dipeptidyl peptidase-IV (DPP IV) inhibitors, could diminish glycaemic variability as a whole.^6,7 Studies have shown that prandial insulins and even more short-acting analogues diminish postprandial hyperglycaemia and consequently glucose variability.⁸
• Educational aid – The Diabetes Expert Advisory Group (EAG) standard 3 states that people with diabetes living in Ireland should have access to self-management education that is appropriate to their needs and in a location that is convenient and acceptable to them.⁹

There are a number of ways to measure glycaemic variability; self-monitoring of blood glucose (SMBG), continuous glucose monitoring and flash glucose monitoring. When deciding which, if any, of these methods is appropriate for a person with diabetes, ADA and NICE guidance recommends considering whether they have the motivation, necessary understanding and skills to appropriately self-monitor blood glucose; considering the patient’s hypoglycaemia history; and ensuring that self-monitoring of blood glucose is only offered as an integral part of patient self-management education.^1,2,3

SELF-MONITORING OF BLOOD GLUCOSE:

It is easier to identify periods of hypoglycaemia and hyperglycaemia when there is a good understanding of daily glucose profiles – and it is also simpler to work on correcting them – but this cannot be adequately accomplished without regular blood glucose monitoring. The Diabetes EAG standard 2 states that people with diabetes living in Ireland should receive diabetes care that is person-centred and encourages self-management.⁴ Therefore, it is essential to work with individuals to determine how often to test their blood glucose, and how their results should be interpreted and acted upon. ADA and NICE guidance recommends SMBG for patients on insulin treatment or oral glucose-lowering medication.^1,2,3 In addition, SMBG is recommended as a method of assessing changes in glucose control following lifestyle adjustments, during intercurrent illness and to ensure safety during certain activities, such as driving.¹ Pattern analysis, a systematic approach to identifying glycaemic trends within SMBG data and then taking appropriate action based upon those results, can be of equal or greater value than measurement of HbA1c levels. The use of pattern analysis involves:⁵

• Establishing pre- and postprandial glucose targets
• Obtaining data on glucose levels, carbohydrate intake, medication administration (type, dosages, timing), activity levels and physical/emotional stress
• Analysing data to identify patterns of glycaemic excursions, assessing any influential factors and implementing appropriate action(s)
• Performing ongoing SMBG in appropriate patients with diabetes to assess the impact of any therapeutic changes made

CONTINUOUS GLUCOSE MONITORING:

Patients who experience persistent problems with unawareness of hypoglycaemia, or repeated hypo- or hyperglycaemia, can benefit from a continuous glucose monitoring system (CGMS) and it can be a useful tool to lower HbA1c.^2,3 These systems work for 24 hours a day and have the advantage of being able to obtain information whilst a patient sleeps. Combining CGMS with continuous subcutaneous insulin infusion (CSII) has been shown to be beneficial in certain scenarios such as: achieving target glucose levels in women with Type 1 diabetes during pregnancy⁶ and reducing nocturnal hypoglycaemia following exercise.⁷ CGMS can play an important role in helping patients control glycaemic variability by:

• Identifying daily trends in blood glucose fluctuations – some devices not only alert the user about lows and highs with alarms, but actually forecast them before they happen so actions can be taken to reduce glycaemic variability
• Evaluating pharmacological, dietary and/or exercise interventions

FLASH GLUCOSE MONITORING:

Flash glucose monitoring is a recently developed method for monitoring glucose levels. The flash glucose monitoring system consists of three primary components:⁸

• A disposable on-body assembly (Sensor) that incorporates a subcutaneously implanted electrochemical glucose sensor and associated electronics;
• A disposable sensor insertion device (Patch Delivery Unit), consisting of two secondary components (Sensor Applicator and Sensor Pack), which is used to adhere the Sensor to the skin of the patient and to insert the Sensor tail about 5.5 mm below the surface of the skin;
• A handheld device (Reader) which collects and displays glucose readings obtained from the Sensor during a scan; the Reader has a built-in strip port with blood glucose and blood ketone meter functionality and a user interface which includes event logging features. 

The System allows the user to query glucose data from the Sensor by bringing a handheld Reader in close proximity to the Sensor. The act of scanning a Sensor provides the user with real-time glucose measurements (glucose values) accompanied by trend information (glucose arrows) that are presented on the Reader display.⁸

THE IMPORTANCE OF DATA IN DIABETES

Developing an accurate and standardised method of glucose data collection and analysis is pivotal to understanding and managing glycaemic variability in practice.⁹

Some glucose systems now come equipped with features and software programmes that simplify the process of collecting and reporting on glucose values and trends for patients who frequently monitor their glucose levels. This data can provide a visual snapshot of a patient’s daily glucose profile facilitating improved patient management, treatment and outcomes.⁹

WHAT IS DKA?

DKA is characterised by hyperglycaemia, ketonaemia and metabolic acidaemia. These changes in the blood are caused by a lack of insulin and simultaneous elevations of the counter-regulatory hormones glucagon, catecholamines, cortisol and growth hormones, stimulating the release of large quantities of free fatty acids into the circulation and initiating ketogenesis.¹

The body attempts to remove the excess ketones by excreting them in the urine and this, along with hyperglycaemic polyuria, leads to dehydration. Associated nausea, vomiting and eventual diminished level of consciousness compound the problem, making it difficult to replace the lost fluid.¹

DKA always represents an acute medical emergency. By the time symptoms appear, intensive hospital treatment will be needed, including continuous insulin infusions, electrolyte replacement and restoration of acid-base balance, as well as treatment of the underlying illness or precipitating factor.¹

Early intervention can shift the treatment of DKA from a reactionary to a proactive process, allowing hospital emergency admissions and deaths to be prevented.

• DKA is the most common cause of death in children with Type 1 diabetes²
• DKA mortality in hospitalised patients has fallen significantly in the last 20 years from 7.96% to 0.67%, but this still represents a high proportion of preventable deaths¹
• Between 2000 and 2009, five hospitals in Birmingham identified a DKA mortality rate of 1.8%41
• In developed countries, mortality in children with DKA is between 0.15% to 0.35%³

KETONES ARE PRODUCED WHENEVER NORMAL GLUCOSE METABOLISM IS UNABLE TO MEET THE ENERGY DEMANDS OF THE BODY AND THE LIVER MOBILISES ENERGY STORED AS FAT.

This occurs in healthy individuals following exercise or during fasting, when glycogen stores are depleted. In people with diabetes, rising blood ketones and rising blood glucose tend to go together. However, without the presence of an adequate insulin response, their ketone levels continue to rise and may reach dangerous levels, resulting in DKA. Rising ketones are thus an important early warning for DKA. Ketones in the urine are an indicator of serum blood levels two hours prior. It is therefore important that blood samples are obtained for assessment of serum levels on a real-time basis. Acting on these results can prevent unnecessary morbidity and mortality, as well as reduce hospital admissions.^1,2,3

It is difficult to determine a ‘normal’ level for circulating ketones in the blood, as individuals vary in terms of duration of fasting, basal metabolic rate, hepatic glycogen stores and mobilisation of amino acids from muscle protein. The general consensus is that levels below 0.6 mmol/L may be regarded as ‘normal’.⁴

WHO IS AT RISK?

Every patient with Type 1 diabetes, and those with advanced Type 2 who are treated with insulin, may be at risk of developing DKA because they are reliant on their insulin therapy to regulate their glucose control. In 40% of DKA cases in patients with Type 1 diabetes, there is no obvious cause to why adequate insulin control is lost but common causative triggers include:⁵

• Infection
• Diarrhoea and vomiting
• Errors or non-compliance with treatment
• Myocardial infarction

WHEN ARE PATIENTS MOST AT RISK?

• During illness, infection and vomiting
• When insulin doses are omitted
• During pregnancy
• During childhood and adolescence
• Elderly patients with co-existing disease
• Insulin pump users
• Patients at initial diagnosis of Type 1 diabetes

Adapted from Kishore 2014 and ADA 2015 ^1,2

Checking for ketones in the urine may help to identify the risk of DKA but is not reliable for diagnosing or monitoring the treatment of ketoacidosis. Blood ketone measurement now represents best practice for diagnosing and monitoring ketoacidosis.¹

• During acute illness, infection or vomiting: every 2-4 hours until recovery ^1,2
• Diagnosis of DKA: hourly until recovery³

GUIDELINES FOR WHEN GLUCOSE REMAINS ELEVATED*

GUIDELINES FOR BLOOD KETONE MEASUREMENTS IN THE MANAGEMENT OF DKA*51

*Local guidelines may vary

DKA MAY BE PREVENTABLE WITH FREQUENT MONITORING OF GLYCAEMIA AND KETOSIS, ALONG WITH TIMELY SUPPLEMENTAL INSULIN.

• Effective ketone monitoring: the presence of raised ketone levels is a major indicator of the risk of DKA. The earlier this is detected, the easier it will be to restore normal ketone control. Prompt, accurate ketone testing is therefore very important in reducing the risk of DKA.¹
• Supporting patient understanding of ketone monitoring: patient education is currently facilitated through the care planning process and aims to help the person with diabetes proactively manage their condition. In this case, improving understanding of the issues around ketone monitoring and DKA can help the person with diabetes minimise their chances of experiencing this complication.²

HOW CAN YOU HELP PATIENTS AVOID THE RISKS OF DKA?

While it is important not to be alarmist, it might also be helpful to make sure the person with diabetes is fully aware of the risks of ketoacidosis. Many make the mistake of thinking that when they are unwell and eating little, they should reduce their insulin dose, when instead they may actually need more insulin than normal. Establishing clear sick-day guidelines can be very helpful for these patients.^3,2

The DAFNE (Dose Adjustment For Normal Eating) programme runs courses for people with diabetes; one of the course aims is to help patients familiarise themselves with ‘sick-day rules’. More information about DAFNE can be found at www.dafne.org.uk. There may also be local education courses available to you.

To aid your patients in the management of sick-days, it helps if they have a plan of what to do beforehand and the relevant phone numbers handy if they need help. Patients may be required to adjust their insulin dose/non-insulin diabetes treatment during intercurrent illness; if this is the case it is important that they receive clear guidelines and protocols to assist them appropriately.^1,2 As response to insulin dosage depends on the individual patient’s metabolism there are no hard and fast rules. Sick-day rules should follow those agreed with the patient’s consultant/specialist unit at the time of insulin initiation or follow local guidelines. In the absence of these the following can be used as a guide where appropriate:³

GENERAL ADVICE FOR THE MANAGEMENT OF SICK-DAYS IN PATIENTS WITH TYPE 1 DIABETES^4,5