Clinical Research Directory

Impact of Dietary Fat and Menstrual Cycle Phases in Type 1 Diabetes

This clinical trial aims to evaluate how variations in dietary fat content and hormonal status influence postprandial glycemic response in individuals with type 1 diabetes (T1D), with a special focus on women. The main objective is to clarify the impact of both factors individually and their interaction, which could inform more personalized strategies for insulin adjustment, optimizing glycemic control, and improving patient outcomes. The main objective is to investigate the effects of low-fat versus high-fat meals, sex, menstrual cycle phases, and their interaction on postprandial glycemic control in adults with T1D treated with advanced hybrid closed-loop (AHCL) insulin delivery systems. Specifically, the study will: * Compare postprandial glycemic responses after standardized low and high-fat meals in men and women with T1D. * Assess the differences in postprandial glycemic responses between early follicular and late luteal phases in women, using standardized meals with low and high fat content. * Identify sex-related differences in glycemic response after equivalent meals. This research addresses the unmet clinical need for precise, tailored postprandial insulin dosing recommendations, especially among women whose insulin sensitivity fluctuates with menstrual phases. The results may contribute to sex-specific predictive models in AHCL systems, reducing acute complications and improving overall quality of life. This is a randomized controlled crossover trial in which each participant serves as her/his own control. Fifty adults will be enrolled: 25 women and 25 men. Women will undergo four mixed-meal tests in random order: * low-fat given during the early follicular phase, * high-fat given during the early follicular phase, * low-fat given during the late luteal phase, * high-fat given during the late luteal phase. The menstrual phase will be confirmed with home-based hormonal monitoring devices that function with urine sample and use a single-use test wand (MIRA system). Men will complete two mixed-meal tests (low-fat and high-fat), in randomized order. All meals will be standardized for carbohydrate content and matched in other macronutrients, except for fat (with a 30-40g difference), administered after an 8-hour fast. The day of the mixed meal test, AHCL systems will be switched from automatic to manual mode just before eating to standardize the prandial insulin dose and to avoid differences in insulin infusion rates in the postprandial state due to algorithm compensations. Continuous glucose monitoring (CGM) and hourly capillary glucose testing will measure the postprandial response. Additional fasting blood samples will assess metabolic, hormonal, and lipid markers. Optional gastric emptying studies may be performed to exclude confounding gastroparesis in selected patients. Participants will be recruited from the endocrinology outpatient unit of La Fe Polytechnic University Hospital . The projected recruitment period is from December 2025 to July 2027, with mixed-meal tests and data collection occurring between January 2026 and December 2027. Women are expected to complete the protocol in 6 weeks (4 tests), while men will require about 2 weeks (2 tests). At baseline, participants will undergo blood tests to rule out endocrine disorders and confirm sex hormone status. Women participating in the study will use the MIRA home device to monitor their hormonal levels, allowing them to accurately determine and record the phases of their menstrual cycle as part of the study protocol. During meal tests, CGM (Freestyle Libre 3) will be used uniformly among subjects. The study dependent variables will be the following: * Postprandial glucose area under the curve - AUC\_PG\_5h * Mean glucose level - MG * Continuous glucose monitoring metrics - TIR, TAR, TBR * Postprandial glucose standard deviation - SD * Postprandial glucose coefficient of variation - CV * Mean amplitude of glycemic excursions - MAGE * Mean of daily differences (MODD) Independent variables are * Type of food: Meals with either low or high fat content. * Sex and Hormonal status: men; women during the early follicular phase; women during the late luteal phase. If successful, this study will inform the development of more sophisticated, individualized insulin dosing algorithms and AHCL system improvements, especially for women with T1D. Results may lead to more effective management strategies, reduced GV, lower incidence of complications, and increased quality of life. Insights may directly support the personalization of diabetes care and improve gender equity in treatment standards.

Effect of a High-Protein, High-Fiber Pre-Fast Meal on Satiety and Glycemic Profiles During Fasting

This randomized crossover study investigates the effect of consuming a high-protein, high-fiber pre-fast meal on subjective satiety and glycemic responses during fasting hours in healthy adults. Participants will complete two dietary conditions in a randomized order: a standardized high-protein, high-fiber pre-fast meal and a low-protein, low-fiber pre-fast meal guided by dietary instructions. Each condition will be followed for two consecutive days and separated by a three-day washout period. Outcomes include subjective appetite sensations during fasting hours, glycemic profiles assessed using continuous glucose monitoring (CGM), and exploratory analyses examining the association between glucose dynamics and appetite sensations.

Exercise Timing and Postprandial Glucose Responses

This interventional crossover study examines the effect of exercise timing relative to meal intake on postprandial glucose responses in healthy, physically active young adults. Participants complete five experimental conditions involving endurance exercise performed before or after breakfast or dinner, as well as a non-exercise control condition, while wearing a continuous glucose monitoring device. Postprandial glucose responses are assessed for the three consecutive meals following each exercise session. Following morning exercise, outcomes are assessed after breakfast, lunch, and dinner on the same day. Following evening exercise, outcomes are assessed after dinner on the same day and after breakfast and lunch on the subsequent day. All meals are standardized and consumed at fixed clock times.

A Clinical Trial to Investigate the Acute Effect of Bragg Apple Cider Vinegar Supplement on Blood Glucose Control in a Healthy Adult Population

The goal of this clinical trial is to evaluate the efficacy of a Bragg ACV supplement on postprandial glucose excursion compared to a placebo following a standardized acute carbohydrate load. Participants will be asked to consume an apple cider vinegar supplement 10 minutes prior to a standardized meal.

Ultra-processed Food Reducing Intervention and Continuous Glucose Monitoring

The goal of this trial is to investigate whether reduction in ultra-processed food intake through diet counseling and education can improve postprandial glucose levels and glycemic variability among Korean healthy adults aged 20-30 years. The main questions it aims to answer are: * Does the reduction in ultra-processed food intake lower postprandial glucose levels and glycemic variability in healthy adults without a history of diabetes? * Does the reduced intake in different ultra-processed food subgroups and items differentially influence postprandial glucose and glycemic variability? * Does other dietary and lifestyle factors (physical activity, sleep, smoking) alter the association between ultra-processed food intake reduction and glycemic variability? Participants will: * Undergo the 10-day pre-intervention monitoring period, during which each participant will wear a continuous glucose monitoring (CGM) device and concurrently report their daily dietary intakes (all food and beverage consumptions) and other lifestyle behaviors (sleep, smoking, physical activity) * After the 10-day pre-intervention monitoring period, participants will be randomized to either intervention or control group * Intervention group: Participants will visit the research site to receive dietitian-led nutrition education and personalized diet counseling targeting reduction of ultra-processed food intake, as well as improving diet quality. Personalized diet counseling will be provided by study dietitian based on participant's records of dietary intakes during the 10-day pre-intervention monitoring period. * Control group: Participants will receive dietitian-led nutrition education and personalized diet counseling targeting general improvement in nutrient intake (based on the national dietary guidelines). * After the intervention, participants will undergo the 10-day post-intervention monitoring period, during which participants will wear a new CGM device for an additional 10 days and continue daily reporting of dietary intakes (all food and beverage consumptions) and lifestyle behaviors (sleep, smoking, physical activity).