Fructose and Glucose and TAS1R2 in Type 1 Diabetes
Fructose and Glucose and TAS1R2 in Type 1 Diabetes
-  BACKGROUND: Individuals with diabetes report innate preference for sweet foods, possibly
 due to genetic variants. In addition, studies have shown that ingestion of fructose
 promotes lower postprandial blood glucose, compared to glucose. However, excessive
 intake may increase triglycerides, uric acid and oxidative stress, due to oxidative
 priority.

 -  AIMS: To investigate the influence of fructose and glucose and taste receptor, type 1,
 member 2 (TAS1R2) in glucose, triglycerides, uremia, oxidative stress, feelings related
 to food intake and palatability of individuals with type 1 diabetes.

 -  METHODS: The trial is a single-blind, two-way crossover (1-week washout) study in 30
 subjects with type 1 diabetes. Blood samples were collected before and 2-hours after the
 participants receive 75g of fructose or 75g of glucose dissolved in 200 ml water.
 Capillary blood glucose were assessed at 30, 90, 120, and 180 minutes to determine
 glucose, and visual analogue scales for measurement of appetite sensation were assessed
 at 70, 120, and 190 minutes.

 -  PURPOSE: The research proposal adds knowledge about the TAS1R2 (Ile191Val) polymorphism
 and around the most suitable monosaccharide for individuals with diabetes type 1.
INTRODUCTION:

 Fructose is transported via the portal vein to the liver, where is rapidly taken up by
 hepatocytes and phosphorylated to fructose-1-phosphate independent of insulin action by the
 enzyme fructokinase. Thus, under normal conditions, fructose is converted mainly to glucose,
 glycogen, and lactate, and to a small extent also to triglycerides. However a
 hypertriglyceridemia has been occur during high intakes of fructose.

 Large amounts of fructose, unlike glucose, may result in increased lactate, pyruvate, and
 uric acid level in healthy subjects and patients with uncontrolled diabetes. However, uric
 acid also has pro-oxidative properties. Possibly, the uric acid neutralizes oxidative damage.

 Sweetness is very attractive to patients with diabetes possibly due to genetic variants. The
 sweet taste receptor is a heterodimer of 2 protein subunits, T1R2 (taste receptor, type 1,
 member 2) and taste receptor, type 1, member 3, located on human chromosome 1. T1R2 is the
 component specific to sweet taste perception because taste receptor, type 1, member 3 is also
 involved in the detection of umami when it dimerizes with taste receptor, type 1, member 1.

 At moment, none study assessed TAS1R variants in individuals with type 1 diabetes.

 EXPERIMENTAL DESIGN:

 This is a randomized, single-blind, two-way, crossover study conducted at the Research Centre
 (Clementino Fraga Filho University Hospital) including 30 adults with type 1 diabetes.

 All volunteers will be instruct to complete the usual dietary record, register their
 capillary blood glucose and to abstain from vigorous physical activity, alcohol, high-fat
 foods and excess caffeine for 24 days before each study day.

 One day before each study day, we will call to volunteer to ask about possible events that
 may influence the biochemical results (such as: infections, flu, fever). If we detect some,
 the test will be rescheduled.

 Basal insulin doses will be retained, and no bolus insulin will be allowed in the morning of
 the day study. The study day will be performed if the blood glucose target level is between
 70 and 200 mg/dL in the morning.

 All volunteers will be assessed two-way crossover in a single blind, randomized fashion, with
 the two studies in the same subject, 1 week apart. The study was divided into two-days (the
 order of which was randomized): one-day with a solution containing glucose and the other with
 a solution containing glucose.

 The subjects were admitted to the Research Centre (Nutritional Laboratory) at approximately
 7-h on the day of study to test capillary blood glucose, collect arterial venous blood
 sample, assessed appetite sensations. After these measurements, they will rapidly drink the
 test solution.

 Palatability ratings of the solution will assessed immediately after. Appetite sensations and
 will be tested using VAS scores immediately before and 70, 130, and 180 minutes after
 solution.

 The second arterial venous blood sample will be collected 185 minutes after solution and test
 capillary blood glucose before and 30, 90, 120, and 180 minutes after solution.

 We excluded volunteers who not complete both tests.

 TEST SOLUTION Solution will be containing 75g of glucose or the same amount of fructose
 diluted in 200 mL of water.These amounts were calculated considering the usual oral glucose
 tolerance test. In addition, at moment, no studies indicate the ability capacity of fructose
 in patients with type 1 diabetes, however, it has been suggested that the absorption capacity
 of fructose in healthy adults varies from 30g to 40g.

 USUAL DIETARY ASSESSMENT Usual dietary intake will be evaluated from 3-day diet records, and
 24-hour recalls will be performed in the day study. All dietary records will be analyzed
 using a local nutritional software.

 ANTHROPOMETRIC ASSESSMENT BMI will be calculated as body weight in kilograms divided by the
 square of height in meters.

 Waist circumference will be determined as the average of two measurements calculated to the
 nearest 0.1cm midway between the lower rib margin and the ilial crest after a normal
 expiration.

 Body composition will be measured by tetrapolar bioelectrical impedance(Biodynamic Model
 450).

 BIOCHEMICAL ASSESSMENT All arterial venous blood sample will be collected by trained
 healthcare professionals with disposable materials in the Research Centre (Nutritional
 Laboratory) and analyzed at Clinical Analysis Laboratory (located on Federal University).

 Glycosylated hemoglobin, total cholesterol, HDL, creatinine, aspartate aminotransferase,
 alanine aminotransferase, and creatinine will be assessed to characterize the study
 population. Glucose, triglycerides, uric acid, pyruvic acid, lactate, and malonaldehyde will
 be measured before and 180 min after ingestion of solution

 Glycosylated hemoglobin will be performed by high-performance liquid chromatography. Glucose,
 total cholesterol, HDL and triglycerides will be measured by enzymatic colorimetric method.
 LDL cholesterol will be calculated by Friedewald equation. Creatinine will be assessed by
 kinetic colorimetric method to calculates the creatinine clearance using the Cockcroft-Gault.
 Pyruvic acid, aspartate aminotransferase and alanine aminotransferase will be determined by
 ultraviolet kinetic method. Uric acid and lactate assessed by enzyme kinetic method.
 Malonaldehyde wil be detected by enzyme-linked immunosorbent assay.

 GENOTYPING Deoxyribonucleic acid (DNA) will be isolated from whole blood using the DNA
 Multi-Sample Kit (Applied Biosystems®) and samples were stored at -20 degree Celsius until
 amplification assays in a Research Laboratory (Laboratory of Molecular Biology, Federal
 University).

 The Ile191Val (rs35874116) polymorphism in TAS1R2 gene will be detected by using a TaqMan
 allelic discrimination assay (ABI number C_55646_20; Applied Biosystems, Foster City, CA)
 with real-time polymerase chain reaction on an ABI 7000 Sequence Detection System (Applied
 Biosystems). Conditions of the polymerase chain reaction is 95 degree Celsius for 10 min and
 40 cycles of 95 degree Celsius for 15 s and 60 degree Celsius for 1 min. Genotyping will be
 verified by using positive control subjects in each 30-well plate as well as rerunning ≥ 5%
 of the samples, which were 100% concordant.

 APPETITE AND PALATABILITY ASSESSMENT Visual analogue scales will be used to assess hunger,
 satiety, fullness, prospective food consumption, and palatability of the test solution, and
 appetite sensations will be evaluated palatability, taste, aftertaste, smell, and visual
 appeal of the solutions.

 Both ratings consists of a visual analogue scale is a premeasured 100-mm scale that can be
 used to represent symptom intensity visually. Each scale is anchored at its ends by opposing
 feelings descriptors. Volunteers will be asked to describe their feelings by placing a
 vertical mark along the line that best represents the intensity of a given feelings about the
 solution. The distance of this mark from the appropriate anchor is measured and then
 translated into a score, ranging from 0 (none or best possible) to 10 (worst possible).

 DIABETES TYPE 1 MANAGEMENT The investigators only included volunteers in a basal-bolus
 regimen with insulin infusion pump or insulin analogs (basal: detemir or glargine; bolus:
 lispro, glulisine or aspart) to avoid glucose oscillations during the experiment.

 All volunteers will be instructed to not modify basal insulin doses and not take the morning
 bolus insulin. The subjects will be admitted in the Research Centre at approximately 7-h and
 will be test theirs capillary blood glucose, and if the blood glucose target level is between
 70 and 200 mg/dL the experiment will be performed.

 Before and during the experiment, we will test the capillary blood glucose levels 5-times
 using Accu-Check® Active, Roche, and will be canceled in glucose ≥350 mg/dL. In this case, we
 will take a bolus correction insulin dosage.

 STATISTICAL Statistical analyzes will be performed with statistical software and significance
 level of 5%.

 Quantitative variables will be described as the mean and standard deviation. Mann-Whitney
 test will be used for between-group comparison and Wilcoxon test to compare the effects of
 solution in each group. Spearman's correlation coefficient and regression will also be used.
Inclusion Criteria:

 -  Type 1 diabetes ( ≥ three years after diagnosis)

 -  Adults

 -  Normal-weight (BMI between 18.5 e 25.0 kg/m2)

 -  Using basal-bolus regimen with insulin infusion pump or insulin analogs (basal:
 detemir or glargine; bolus: lispro, glulisine or aspart).

 Exclusion Criteria:

 -  Smokers;

 -  Drinkers;

 -  Use of exogenous hormone (with the exception of insulin);

 -  Use of antibiotics, anti-inflammatories or oral antidiabetics pharmacotherapy;

 -  Diagnosis of nephropathy;

 -  Diagnosis of liver diseases;

 -  With other types of diabetes family history;

 -  Visual disturbances.