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DIABETES

What is Diabetes?

There are three main types of diabetes, type 1, type 2 and gestational diabetes (diabetes whilst pregnant). Type 2 diabetes mellitus (T2DM) comprises 90-95% of total diabetes cases and therefore will be the primary form of diabetes referred to in this page. 2023 data shows more than 4.4 million people in the UK are living with a diabetes diagnosis, with an approximate further 1.2 million living with T2DM that is not yet undiagnosed.

T2DM is a chronic metabolic condition, characterised by insulin resistance causing hyperglycaemia (elevated blood glucose levels). Insulin is a hormone made in the pancreas. It helps regulate blood glucose levels by facilitating the removal of glucose (sugar) from the blood into the liver, muscle and fat cells, where it is used as energy. If our cells don’t recognise and respond to insulin in this way, it is referred to as insulin resistance.

Role of Insulin

Glucose increases in blood after consumption of food > insulin is released into blood > insulin binds to the cell membrane (i.e. muscle cell) > GLUT4 (glucose transporter) moves to the cell membrane > glucose is facilitated into the cell.

Healthy

T2DM

Insulin resistance is caused by a combination of factors related to excess body fat, poor diet quality, a lack of physical activity and genetics. Over time, the pancreas can struggle to produce enough insulin to sufficiently control blood sugar, leading to chronically elevated blood sugar levels. Without appropriate management, this can further damage blood vessels and impact organ function, contributing to health issues such as heart disease, kidney disease and vision loss.

T2DM has an insidious onset, meaning it progresses over time (typically over many years) and can have no obvious symptoms at first. The term ‘prediabetes’ is used when blood glucose levels are higher than normal, but not yet in T2DM range. It is estimated that 13.6 million people have pre-diabetes in the UK. Diagnosis of T2DM can still be prevented or significantly delayed from the prediabetes stage, with appropriate modifications to physical activity levels and diet.

Contributing Factors

Non-modifiable

Family history
45years or older
Ethnicity (African American, Hispanic, American Indian, Pacific Islander, Asian American are at greater risk)

Modifiable

Overweight or obese, particularly excess visceral adiposity (fat around organs)
Physically inactive, specifically less than 3 days of physical activity per week
Diet quality, particularly excess caloric intake
Smoking

Diagnosis & Managment

Diagnosis of T2DM requires blood tests measuring blood glucose levels. The primary test used to diagnose T2DM or prediabetes is the Haemoglobin A1c (HbA1c), which measures average blood glucose levels over the past 3 months. A measure of 48mmol/mol (6.5%) on the HbA1c is recognised as the cut-off point for diagnosis of T2DM, however a value slightly lower than this also doesn’t rule diagnosis out. For context, the ‘normal’ range is recognised as 4% - 5.6% on the HbA1c. Other tests such as fasting plasma glucose can also be used when diagnosing T2DM.

Medical management of T2DM typically involves regular monitoring of blood glucose levels (BGL), alongside an individualised medication plan. Continuous glucose monitors (CGM’s) are now routinely used to provide instant monitoring of BGL’s, allowing for real-time feedback of an individual’s response to certain foods, exercise, etc.

Alongside an individualised medication plan, it is well established that lifestyle modifications are vital when aiming to manage T2DM, or prevent pre-diabetes from progressing. Physical activity is one of the most well researched interventions shown to offer numerous benefits to diabetic or pre-diabetic individuals, in addition to weight loss if overweight, smoking cessation and improvement in dietary habits.

Glucose monitor

Role of Physical Activity & Exercise

Exercise has consistently been shown to be an important tool in the prevention and management of T2DM. Exercise has the potential to improve glycaemic (blood glucose) control, body composition and physical function in those with T2DM or pre-diabetes.

There are a range of mechanisms behind the positive impact of exercise in T2DM. A primary factor is improved insulin sensitivity, where the body becomes more responsive to insulin, therefore promoting increased removal of glucose from the blood vessels.

Secondly, exercise has a similar effect on glucose cells as insulin, independent to the previously mentioned improvements in insulin sensitivity. This is caused by mobilisation of a glucose transporter, named GLUT4, which facilitates glucose uptake into the muscle cells. The increase in number and function of GLUT4 lasts for 24-36hrs post exercise. This leads to the recommendation of having no more than 2 days between exercise bouts for effective improvements in glycaemic control.

Role of Exercise in Blood Glucose Regulation

Glucose increases in blood after consumption of food > exercise mobilises GLUT4 (glucose transporter) > GLUT4 moves to the cell membrane > glucose is facilitated into the cell.

Both resistance and aerobic (cardio) training have shown beneficial effects on glycaemic control, with a combination likely to elicit the greatest positive effect. The greatest reductions in Hba1c measures have been observed with a combined exercise program. For both resistance and aerobic exercise, the intensity, frequency and duration are all regarded as important variables when aiming to improve glycaemic control and effectively manage T2DM.

A minimum of 210mins of moderate intensity exercise per week is recommended, through a combination of aerobic and resistance exercise. For vigorous exercise, regarded as >70% of max heart rate, a minimum of 125mins per week is recommended. Greater intensities of aerobic training have typically shown improved outcomes in HbA1c and other metabolic markers, however this is only recommended when realistic and practical for the individual.

Resistance training consisting of large muscle groups is recommended twice weekly. Similar to aerobic training, higher intensities are recommended if achievable and should be progressively overloaded when tolerated.

Further benefits of exercise in those with T2DM or pre-diabetes include improved metabolic markers (in addition to blood glucose), cardiovascular fitness, mental health and management of other potential co-morbidities.

The Vitruvian Team.

Exercise/Physical Activity in Individuals with Type 2 Diabetes: A Consensus Statement from the American College of Sports Medicine.

Kanaley, et al. Medicine and Science in Sports and Science. 2022

Exercise prescription for patients with type 2 diabetes and pre-diabetes: A position statement from Exercise and Sport Science Australia.

Hordern, et al. Journal of Science and Medicine in Sport. 2011

Type 2 Diabetes in Adults: Management.

National Institute for Health and Care Excellence Guidelines. Updated 2022

Effect of Physical activity on Insulin Resistance, Inflammation and Oxidative Stress in Diabetes Mellitus.

Venkatasamy et al. Journal of Clinical and Diagnostic Research. 2013

Exercise-induced increase in muscle insulin sensitivity.

Holloszy, J. Journal of Applied Physiology. 2005

Diabetes UK. https://www.diabetes.org.uk/

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