Three separate interventions will be undertaken with the primary outcome of improving pulse wave velocity. Initially, age and BMI-matched men and post-menopausal women, all with type 2 diabetes, will be treated with allopurinol (20 men, 20 women) for 6 months, in order to reduce serum uric acid (SUA) concentrations relative to placebo (10 men, 10 women). In a second intervention, dietary fructose will be restricted for a period of 6 months in type 2 diabetes (T2D) subjects who will maintain a stable weight (20 men, 20 women). In a third intervention, dietary fructose will be restricted for a period of 6 months in type 2 diabetes (T2D) subjects who will achieve a caloric deficit and weight reduction (20 men, 20 women). At the beginning and end of each of the studies, measures of arterial stiffness will be combined with assessments of endothelial function (flow-mediated dilation and insulin stimulated leg blood flow), measurements of systemic inflammation and oxidative stress.
Sedentary, overweight and obese subjects diagnosed with T2D, ages 40-75 years old, will be recruited from the local community, via the University of Missouri's Endocrinology Clinic and the primary care clinics. During screening, and after consent, anthropometrics (waist circumference and body composition) will be obtained and fasting blood will be drawn for serum chemistries, A1c, complete blood count, liver and kidney function. Screening will also include completion of an oral glucose tolerance test with measurements of arterial stiffness and assessment of endothelial function. Following screening, eligible subjects will be assigned to one of the four groups (allopurinol, placebo, fructose restriction/isocaloric, or fructose restriction/hypocaloric). Allopurinol will be titrated to achieve a target dose of 300 mg/day. Along with placebo, this arm of the study is double-blinded. A separate group of men and women will be assigned to the isocaloric fructose-restriction study in which dietary fructose is replaced by starch and body weight is held constant. Lastly, a separate group of men and women will be assigned to the hypocaloric fructose-restriction in which baseline caloric intake will be reduced by 500 Calories/day while baseline intakes of protein and fat will remain constant. The subjects in these groups will not be blinded to the dietary treatment but the staff making measurements will be. Subjects in the four groups will be matched for age and BMI.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
34
6 month of consumption a low fructose diet
6 months of allopurinol treatment with the goal of decreasing uric acid compared to control group
6 months of placebo treatment
6 month of consumption a low fructose diet with a 500 Calorie/day energy restriction
University of Missouri
Columbia, Missouri, United States
Carotid Femoral Pulse Wave Velocity (cfPWV)
It is the gold standard non-invasive index of arterial stiffness. Transit time between carotid and femoral pressure waves is calculated using the foot-to-foot method. cfPWV is calculated as distance traveled by the pulse wave (i.e., femoral location-sternal notch minus sternal notch-carotid location) divided by pulse transit time. All the measurements will be done by the same blinded technician
Time frame: This will be assessed at baseline and 6 months (final). The goal is to assess changes from baseline when compared to final time point.
Brachial Artery Flow Mediated Dilation (FMD)
Brachial artery FMD will be assessed at baseline and final. FMD is a measurement of conduit artery endothelial function. FMD is assessed immediately after each PWV measurement. Shear rate AUC until peak diameter is calculated as stimulus for FMD and used in covariate analysis as described. All measurements will be performed, under co-I supervision by the same blinded technician.
Time frame: Baseline and 6 months (final). The goal is to assess changes from baseline when compared to final time point.
Insulin-stimulated Leg Blood Flow
We will perform a hyperinsulinemic euglycemic clamp to evaluate insulin-stimulated leg blood flow (to be assessed via Doppler ultrasound). Insulin will be infused at a constant rate to mimic postprandial insulin concentrations and glucose maintained at fasting values via a variable 20% dextrose infusion. Femoral artery blood flow will be assessed at the beginning and at end of the 60-minute insulin infusion, and data are presented as percent of change from pre-insulin infusion values.
Time frame: The goal is to assess insulin stimulated responses in blood flow after 6 mo of intervention.
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