Type 2 diabetes: Can changing dietary habits delay diagnosis?

Type 2 diabetes is a chronic disorder characterised by either insulin deficiency or resistance [1]. It is the most common form of diabetes as it affects 90-95% of patients [2]. According to the World Health Organisation (WHO) more than 400 million people are diagnosed with type 2 diabetes on a global scale [3]. Most patients report symptoms of excessive urination, tiredness, excessive thirst as well as weight loss [4]. Type 2 diabetes has been associated with dramatic consequences on overall health as it has been linked with cardiovascular and mental health disorders [5]. Also, it has been named as the sixth superior cause of disability worldwide [5]. All of the above contribute to premature mortality. This is further supported by research which illustrated that life expectancy of patients with diabetes is reduced by seven years when compared to healthy individuals [6].

The roots of origin of type 2 diabetes have not been clearly established yet. However, scientists have identified a range of risk factors which have been proven to assist its development [7]. Such factors include both non-modifiable (e.g. increasing age, family history and ethnicity) as well as modifiable (e.g. diet and lack of physical activity) all of which can contribute to type 2 diabetes. Given this, healthcare practitioners thrive to promote a range of lifestyle changes targeting the aforementioned modifiable risk factors in an attempt to prevent or delay the progression of type 2 diabetes in high risk individuals.

• Switch to wholegrain carbohydrates and fibre: Fibre refers to complex carbohydrates which neither be digested nor absorbed. As a result, glucose release in the bloodstream slows down thereby stabilizing blood sugar levels. Fibre has been proven to improve glycemic control as well as blood lipids and body weight in a recent systematic review which evaluated the impact of wholegrains on diabetes prevention [8]. The recommended daily intake of fibre for adults is 30 grams per day. Examples of fibre-rich food include brown rice, oats, pulses as well as brown pasta.
• Reduce consumption of free sugars: Free sugars are defined as “all monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook or consumer and sugars naturally present in honey, syrup, fruit juice and fruit juice concentrates” [9]. Every day sources of free sugars include biscuits, added sugar in coffee or tea as well as shakes. Apart from their lack of nutrients, such products provide a substantial amount of calories leading to weight gain. Weight gain has been one of the most common risk factors associated with type 2 diabetes therefore high risk individuals are highly recommended to stick to no more than 30 grams of free sugar per day.
• Reduce dietary salt intake: Increased consumption of sodium has been globally associated with increasing blood pressure. Likewise to weight gain, high blood pressure is a strong predictor of type 2 diabetes. As such high risk patients are advised to eat a maximum of 6 grams of salt per day.
• Limit alcohol: The recommended alcohol intake for adults is no more than 14 units per week. A unit of alcohol is measures as 10ml of a drink such as a glass of wine or 1⁄2 pint of beer. Alcohol is a source of both excess calories and free sugars both of which contribute to type 2 diabetes development. As such, susceptible individuals are advised to stick to the above recommendation.
• Reduce consumption of red and processed meat: Processed meat is defined as “meat that has been transformed through salting, curing, fermentation, smoking or other processes to enhance flavour or improve preservation” [10]. Examples include bacon and sausages. Red and processed meat is an independent risk factor of type 2 diabetes development. Large epidemiological studies conducted in previous years illustrated a strong positive correlation between intake of red and processed meat and type 2 diabetes development [11; 12; 13]. Further to the above, red and processed meat has been linked with weight gain, smoking and a reduction in physical activity further increasing the risk of type 2 diabetes. As such high risk individuals are recommended to eat a maximum of 70 grams per day.
• Increase consumption of oily fish: Oily fish describes a species of fish which have oil in their soft tissues such as salmon and tuna. In recent years, oily fish has been linked with a lower risk of developing diabetes urging susceptible individuals to meet the recommendation of at least 2 portions per week [14].
• Consume more fruits and vegetables: An increase in fruit and vegetable intake has been associated with a reduction in dietary free sugars. Given this, UK practitioners encourage high risk individuals to follow the 5 a day recommendation in an attempt to stabilise blood sugar levels. Examples of 1 portion include 1 medium-sized fruit, 150 ml of fruit juice and half a plate of vegetables.

The Mediterranean diet originated from the dietary preferences of individuals living in Crete, the rest of Greece and South Italy [15]. It has been described as one of the healthiest eating practices worldwide [16]. The main constituents of the Mediterranean diet are plant-based food products, fresh fruit, olive oil, dairy products as well as wine [15]. Another key feature of the diet is the lack of processed and red meat which reduces the intake of saturated fats to no more than 8% of the daily energy intake [15]. The characteristics of the Mediterranean diet are concurrent with the dietary advice offered to susceptible individuals therefore it is of no surprise that healthcare practitioners encourage people to adapt to this diet. A recent publication concluded that adherence to the Mediterranean diet significantly reduces the prospect of developing any form of diabetes by 21% [17]. This is further supported by the ATTICA study which took place in Greece and illustrated a negative relationship between adherence to the Mediterranean diet and the risk of developing any form of diabetes [16].

The WHO has recommended the use of herbal plants as potential approaches for the management of type 2 diabetes. Up to date, more than 800 plants with hypoglycaemic properties have been identified, two of which have been proven to be effective. Given this, researchers are now investigating their potential as a means of prevention or delayed progression of type 2 diabetes. These include:

• Fenugreek: Fenugreek (Trigonella foenum-graecum) was originally produced in the Middle East and belongs to the family of Leguminosae plants which contain an alkaloid trigonelline and choline [18]. These are derived from the dried ripe seeds and exert hypoglycaemic effects [18]. The high fibre content of the seeds slows down carbohydrate absorption thereby stabilising blood sugar levels [19].
• Ginger: Ginger (Zingiber officinale roscoe) belongs to the family of Zingiberaceae plants [20]. It is the most widely consumed spice worldwide [21]. It consists of volatile oils and non-volatile pungent compounds which exert anti-diabetic properties [22].