Utilizing Glycaemic Index: An Investigation of the Glycaemia and Cognition in Type 2 Diabetes
Condition: Diabetes Mellitus, Type 2; Cognitive Impairment
MeSH terms: Diabetes Mellitus; Diabetes Mellitus, Type 2
Study type: Interventional

Summary: 
      The current study aims to investigate the effects of two GI diets (low vs. high GI) in a
      sample (25 participants) that has diet controlled type 2 diabetes. This sample has been
      chosen as those with diabetes have been shown to suffer with poor glucose tolerance, along
      with the associated deficits such as compromised cognitive function. Therefore, it is
      expected that differences produced by the two diets on blood glucose concentrations and
      cognitive performance will be greater than those previously seen. If this is the case after
      analyzing the results, it will provide a potential strategy (diet) for improving glucose
      tolerance and cognitive performance in a vulnerable section of the population.
    

Detailed description: 
      With the introduction of the glycemic index in 1981, which can be defined as a measure of
      carbohydrate quality within foods, there has been a wealth of research into its' application
      to cognitive function. This research has been based on the theory that the availability of
      blood-borne glucose can have an impact on cognitive performance. This is supported by work
      that has shown that the brain consumes an immense amount of energy relative to the rest of
      the body, but possesses minute stores of glycogen which it could convert into its main energy
      source; glucose. This means the brain is reliant on the glucose supplied to it by the blood,
      which in turn requires the consumption of foods that can be broken down into glucose.

      With this in mind, the vast majority of literature has focussed on the acute effects that
      foods differing in glycemic values may have on cognitive function, and have found many
      relevant findings such as less cognitive performance decline across the morning for children
      who eat a low GI breakfast. This could be explained as a low GI breakfast will contain higher
      quality carbohydrates, or in other words; slower absorbing carbohydrates, which would suggest
      the brain has access to a steady supply of glucose across the more.

      Interesting work in the field of physiology has proposed the presence of a second meal
      effect, which can be defined as the glycemic index of a meal having an effect on the glycemic
      response to a subsequent meal. Surprisingly, there are very few pieces of psychology
      literature that investigate the possibility of a second cognitive meal effect, which is based
      on the theory that if a meals' GI can affect the glycemic response to a subsequent meal, then
      it may also have an effect on cognitive function. However, research into this has found some
      evidence for such an effect.

      Although, there has been a wealth of research into the glycemic index as a whole, the
      methodology varies greatly from study to study. These problems are most evident when looking
      at the times that cognitive function tests are administered. For research based upon a theory
      that relies on availability of blood-borne glucose, the times of cognitive testing do not
      always align themselves with the time points that the glycemic response indicates are ideal
      testing times.

      An initial study by the investigators looked to resolve the current lack of consistency
      amongst previous research by providing participants with three meals throughout the course of
      a day, whilst measuring blood glucose via finger prick. The aim was to identify where the
      biggest differences in blood glucose occur when looking at the results of a sample of 24
      healthy participants. The time points identified would then provide information as to when
      significant differences in cognitive performance throughout the day may be expected.

      A second study fed a larger healthy sample (40 participants) the same meals, but also
      included a cognitive task battery. Results from the blood glucose concentrations supported
      results from study 1, with the two diets producing measureable differences in the glycaemic
      profiles produced across a test day. This is another step into potentially producing a diet
      that could promote healthy glucose regulation and cognitive function.

      The current study aims to investigate the effects of two GI diets (low vs. high GI) in a
      sample (25 participants) that has diet controlled type 2 diabetes. This sample has been
      chosen as those with diabetes have been shown to suffer with poor glucose tolerance, along
      with the associated deficits such as compromised cognitive function. Therefore, it is
      expected that differences produced by the two diets on blood glucose concentrations and
      cognitive performance will be greater than those previously seen. If this is the case after
      analyzing the results, it will provide a potential strategy (diet) for improving glucose
      tolerance and cognitive performance in a vulnerable section of the population.
    

Intervention name(s): Low Glycaemic Diet; High Glycaemic Diet
Intervention type(s): Dietary Supplement; Dietary Supplement
Intervention description(s): This intervention is a diet consisting of a Low GI breakfast, lunch and snack meal.; This intervention is a diet consisting of a High GI breakfast, lunch and snack meal.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: All participants took part in both conditions
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: glycaemic index; glycaemia; diabetes mellitus; type 2 diabetes