Preventing type 2 diabetes: risk identification and interventions for individuals at high risk
This is an extract from the guidance. The complete guidance is available at guidance.nice.org.uk/ph38
- Behaviour change
- Brief advice
- Brief intervention
- Computer-based risk-assessment tools
- Diabetes prevention programmes
- Glycated haemoglobin (HbA1c)
- Impaired fasting glucose (IFG)
- Impaired glucose tolerance
- Impaired glucose regulation (IGR)
- Intensive lifestyle-change programmes
- Level of risk
- Moderate-intensity physical activity
- Oral glucose tolerance test
- Vigorous-intensity physical activity
- Weight-loss programmes
- Weight management
Evidence-based behaviour-change advice includes:
helping people to understand the short, medium and longer-term consequences of health-related behaviour
helping people to feel positive about the benefits of changing their behaviour
building the person's confidence in their ability to make and sustain changes
recognising how social contexts and relationships may affect a person's behaviour
helping plan changes in terms of easy steps over time
identifying and planning for situations that might undermine the changes people are trying to make (including planning explicit 'if–then' coping strategies to prevent relapse)
encouraging people to make a personal commitment to adopt health-enhancing behaviours by setting (and recording) achievable goals in particular contexts, over a specified time
helping people to use self-regulation techniques (such as self-monitoring, progress review, relapse management and goal revision) to encourage learning from experience
encouraging people to engage the support of others to help them to achieve their behaviour-change goals.
(This is adapted from NICE's guidance on behaviour change.)
Typically, for diabetes prevention, brief advice might consist of a 5–15 minute consultation. The aim is to help someone make an informed choice about whether to make lifestyle changes to reduce their risk of diabetes. The discussion covers what that might involve and why it would be beneficial. Practitioners may provide written information in a range of formats and languages about the benefits and, if the person is interested in making changes, may discuss how these can be achieved and sustained in the long term.
Brief interventions for diabetes prevention can be delivered by GPs, nurses, healthcare assistants and professionals in primary healthcare and the community. They may be delivered in groups or on a one-to-one basis. They aim to improve someone's diet and help them to be more physically active. A patient-centred or 'shared decision-making' communication style is adopted to encourage people to make choices and have a sense of 'ownership' of their lifestyle goals and individual action plans. Providers of brief interventions should be trained in the use of evidence-based behaviour-change techniques for supporting weight loss through lifestyle change.
These tools identify a set of risk characteristics in patient health records. They can be used to interrogate GP patient databases and provide a summary score to indicate someone's level of risk. Examples include the Cambridge diabetes risk score and the Leicester practice score.
Diabetes prevention programmes comprise two integrated components: first, risk identification services and second, intensive lifestyle-change programmes. Participants are acknowledged as the decision-makers throughout the process. Also see 'Intensive lifestyle-change programmes'.
Glycated haemoglobin (HbA1c) forms when red cells are exposed to glucose in the plasma. The HbA1c test reflects average plasma glucose over the previous 8–12 weeks. Unlike the oral glucose tolerance test, an HbA1c test can be performed at any time of the day and does not require any special preparation, such as fasting.
HbA1c is a continuous risk factor for type 2 diabetes. This means there is no fixed point when people are (or are not) at risk. The World Health Organization recommends a level of 48 mmol/mol (6.5%) for HbA1c as the cut-off point for diagnosing type 2 diabetes in non-pregnant adults. For the purposes of this guidance, the range 42–47 mmol/mol (6.0–6.4%) is considered to be 'high risk'.
Impaired fasting glucose is defined as a fasting plasma glucose between 6.1 and 6.9 mmol/l.
This is a risk factor for future diabetes and/or other adverse outcomes. The current WHO diagnostic criteria for impaired glucose tolerance are: a fasting plasma glucose of less than 7.0 mmol/l and a 2-hour venous plasma glucose (after ingestion of 75 g oral glucose load) of 7.8 mmol/l or greater, and less than 11.1 mmol/l.
This is a risk factor for future diabetes and/or other adverse outcomes. The term covers blood glucose levels that are above the normal range but are not high enough for the diagnosis of type 2 diabetes. It is used to describe the presence of impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) as defined by the WHO.
IFG is defined as fasting plasma glucose 6.1 to 6.9 mmol/l IGT is defined as a fasting plasma glucose (FPG) less than 7 mmol/l and 2-hour venous plasma glucose (after ingestion of 75 g oral glucose load) of 7.8 mmol/l or greater and less than 11.1 mmol/l.
Impaired fasting glucose and impaired glucose tolerance can occur as isolated, mutually exclusive conditions or together, that is, fasting plasma glucose between 6.1 and 6.9 mmol/l and 2-hour glucose of 7.8 mmol/l or greater and less than 11.1 mmol/l during the oral glucose tolerance test .
A structured and coordinated range of interventions provided in different venues for people identified as being at high risk of developing type 2 diabetes (following a risk assessment and a blood test). The aim is to help people become more physically active and to improve their diet. If the person is overweight or obese, the programme should result in weight loss. Programmes may be delivered to individuals or groups (or involve a mix of both) depending on the resources available. They can be provided by primary care teams and public, private or community organisations with expertise in dietary advice, weight management and physical activity.
The terms 'high', 'intermediate' and 'low' risk are used to refer to the results from a risk assessment tool. These terms are used instead of specific numerical scores because the tools have different scoring systems. The term 'moderate risk' is used to denote a high risk assessment score where a blood test did not confirm that risk (FPG less than 5.5mmol/l or HbA1c less than 42mmol/mol [6.0%]). A fasting plasma glucose of 5.5–6.9 mmol/l or an HbA1c level of 42–47 mmol/mol [6.0–6.4%] indicates high risk.
Moderate-intensity physical activity requires an amount of effort and noticeably accelerates the heart rate. Examples include brisk walking, housework and domestic chores. On an absolute scale, moderate-intensity is defined as physical activity that is between 3 and 6 metabolic equivalents (METs).
An oral glucose tolerance test involves measuring the blood glucose level after fasting, and then 2 hours after drinking a standard 75g glucose drink. Fasting is defined as no calorie intake for at least 8 hours. More than one test on separate days is required for diagnosis in the absence of hyperglycaemic symptoms.
Pre-diabetes refers to raised (but not in the diabetic range) blood glucose levels (also known as non-diabetic hyperglycaemia, impaired glucose regulation). It indicates the presence of impaired fasting glucose and/or impaired glucose tolerance. People with pre-diabetes are at increased risk of getting type 2 diabetes. They are also at increased risk of a range of other conditions including cardiovascular disease.
Vigorous-intensity physical activity requires a large amount of effort, causes rapid breathing and a substantial increase in heart rate. Examples include running and climbing briskly up a hill. On an absolute scale, vigorous intensity is defined as physical activity that is above 6 metabolic equivalents (METs).
Effective weight-loss programmes are structured lifestyle-change programmes to help people lose weight in a sustainable way. They:
are based on an assessment of the individual
address the reasons why someone might find it difficult to lose weight
are tailored to individual needs and choices
are sensitive to the person's weight concerns
are based on a balanced, healthy diet
encourage regular physical activity
utilise behaviour-change strategies.
In this guidance, the term weight management includes:
assessing and monitoring body weight
preventing someone from becoming overweight (body mass index [BMI] of 25–29.9 kg/m², or 23–27.4 kg/m2 if they are of South Asian or Chinese descent)
preventing someone from becoming obese (BMI greater than or equal to 30 kg/m², or 27.5 kg/m2 or above if they are of South Asian or Chinese descent)
helping someone who is overweight or obese to achieve and maintain a 5–10% weight loss and progress to a healthy weight (BMI of 18.5–24.9 kg/m², or 18.5 to 22.9 kg/m2 if they are of South Asian or Chinese descent) by adopting a healthy diet and being physically active.