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The goal of this study is to learn whether eating a small serving of almonds before meals can improve blood sugar control in adults who have early signs of problems with blood sugar regulation. The main questions it aims to answer are:
Large rises in blood sugar after eating are an early warning sign of type 2 diabetes, and simple dietary strategies may help lower this risk. This study aims to understand whether eating a small serving of almonds before meals can help reduce postprandial blood sugar levels in adults who are at increased risk for developing type 2 diabetes. Participants will take part in two phases of the study: one conducted in a research clinic to carefully measure short-term blood sugar responses, and another conducted while participants follow a provided diet at home over a longer period. Sometimes participants will eat almonds before meals, and sometimes they will not. The study hypothesis is that eating almonds before meals will lower blood sugar rises after eating, and that some people will benefit more than others in a consistent way that can be observed both in the clinic and during everyday living.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Randomization Sequence 1 | Experimental | One of the randomization sequences. Phase 1: MMTT+, MMTT-, MMTT+, MMTT- | Phase 2: SAD+, SAD-. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 2 | Experimental | One of the randomization sequences. Phase 1: MMTT-, MMTT+, MMTT-, MMTT+ | Phase 2: SAD+, SAD-. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 3 | Experimental | One of the randomization sequences. Phase 1: MMTT+, MMTT-, MMTT-, MMTT+ | Phase 2: SAD+, SAD-. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Premeal almond ingestion | Dietary Supplement | Premeal almond ingestion (18 g; ~100 kcal) 30 minutes prior to meal |
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| Measure | Description | Time Frame |
|---|---|---|
| Postprandial glucose assessed during acute meal test | The primary endpoint will be the difference in plasma glucose incremental area under the curve (iAUC) assessed via intravenous blood sampling over three hours following a standardized mixed meal tolerance test (MMTT) with premeal ingestion of 18 g of almonds 30 minutes prior (MMTT+) compared to without (MMTT-). This effect will be averaged across the replicated acute challenge visits in the repeated crossover design. | Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
| Measure | Description | Time Frame |
|---|---|---|
| Interindividual variability in the postprandial glucose assessed during acute meal test | Variability in response to the single-dose, acute premeal almond supplementation prior to the MMTT will be characterized according to previously established procedures using Pearson's correlation between the first and second replicate of the control-adjusted treatment effect (i.e., MMTT+ vs MMTT-). That is, the correlation between the difference in iAUC during the first crossover trial (i.e., iAUC during MMTT+ minus iAUC during MMTT-) and the difference in iAUC during the second crossover trial (i.e., iAUC during MMTT+ minus iAUC during MMTT-). |
| Measure | Description | Time Frame |
|---|---|---|
| Acute postprandial glucose | The difference in plasma glucose assessed via intravenous blood sampling over three hours following a standardized mixed meal tolerance test (MMTT) with premeal ingestion of 18 g of almonds 30 minutes prior (MMTT+) compared to without (MMTT-). This effect will be averaged across the replicated acute challenge visits in the repeated crossover design. | Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Kaja Falkenhain, PhD | Contact | 225-763-2558 | kaja.falkenhain@pbrc.edu |
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Pennington Biomedical Research Center | Baton Rouge | Louisiana | 70808 | United States |
Data will be shared upon reasonable request to the study investigator and upon successful execution of a data transfer/sharing agreement.
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| ID | Term |
|---|---|
| D011236 | Prediabetic State |
| D007333 | Insulin Resistance |
| D018149 | Glucose Intolerance |
| ID | Term |
|---|---|
| D003920 | Diabetes Mellitus |
| D044882 | Glucose Metabolism Disorders |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |
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The study consists of two phases using a crossover interventional design. In Phase 1, participants complete two cross-over trials (i.e., a total of four acute visits), including twice with an almond preload (active condition) and twice without (control condition). In Phase 2, participants complete one cross-over trial (i.e., a total of two 10-day study periods), including one with an almond preload prior to each meal (active condition) and one without (control condition). Given the repeated crossover nature of Phase 1 and the single crossover nature of Phase 2 of the study, there are a total of 8 possible visit sequences (i.e., "arms").
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| Randomization Sequence 4 | Experimental | One of the randomization sequences. Phase 1: MMTT-, MMTT+, MMTT+, MMTT- | Phase 2: SAD+, SAD-. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 5 | Experimental | One of the randomization sequences. Phase 1: MMTT+, MMTT-, MMTT+, MMTT- | Phase 2: SAD-, SAD+. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 6 | Experimental | One of the randomization sequences. Phase 1: MMTT-, MMTT+, MMTT-, MMTT+ | Phase 2: SAD-, SAD+. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 7 | Experimental | One of the randomization sequences. Phase 1: MMTT+, MMTT-, MMTT-, MMTT+ | Phase 2: SAD-, SAD+. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Randomization Sequence 8 | Experimental | One of the randomization sequences. Phase 1: MMTT-, MMTT+, MMTT+, MMTT-, | Phase 2: SAD-, SAD+. In Phase 1, MMTT+ refers to a mixed meal tolerance test with premeal almond ingestion (active condition). MMTT- refers to a mixed meal tolerance test without premeal almond ingestion (control condition). In Phase 2, SAD+ refers to the 10-day controlled feeding diet period using a Standard American Diet with thrice daily premeal almond ingestion (active condition). SAD- refers to the 10-day controlled feeding diet period using a Standard American Diet without premeal almond ingestion (control condition). |
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| Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
| Consistency between acute glycemic response and longer-term glycemic control | Whether the individual glucose-lowering effect of the almond preload observed during the acute, repeated crossover, controlled in-laboratory MMTT predicts an individual's glycemic control during the 10-day, free-living, controlled-feeding phase in which almonds will be consumed thrice daily prior to each main meal on the background of a Standard American diet. We will evaluate this via the regression coefficient derived from a linear regression with the magnitude of the acute treatment effect in Days 1-4 (i.e., the difference in iAUC between MMTT+ and MMTT- averaged between both crossover trials) as the predictor and the magnitude of the treatment effect in Days 5-25 (i.e., the difference in average iAUC across the 10-day controlled feeding diet periods between MMTT+ and MMTT-) as the outcome. | Days 1-4: Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. Days 5-25 |
| Acute postprandial gastric emptying | The difference in acetaminophen appearance (gastric emptying) assessed via intravenous blood sampling over three hours following a standardized mixed meal tolerance test (MMTT) with premeal ingestion of 18 g of almonds 30 minutes prior (MMTT+) compared to without (MMTT-). This effect will be averaged across the replicated acute challenge visits in the repeated crossover design. | Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
| Acute postprandial insulin | The difference in plasma insulin assessed via intravenous blood sampling over three hours following a standardized mixed meal tolerance test (MMTT) with premeal ingestion of 18 g of almonds 30 minutes prior (MMTT+) compared to without (MMTT-). This effect will be averaged across the replicated acute challenge visits in the repeated crossover design. | Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
| Acute postprandial glucagon-like peptide 1 | The difference in plasma glucagon-like peptide 1 assessed via intravenous blood sampling over three hours following a standardized mixed meal tolerance test (MMTT) with premeal ingestion of 18 g of almonds 30 minutes prior (MMTT+) compared to without (MMTT-). This effect will be averaged across the replicated acute challenge visits in the repeated crossover design. | Days 1-4: -35 minutes, -5 minutes, 15 minutes, 30 minutes, 60 minutes, 90 minutes, 120 minutes, 180 minutes relative to ingestion of premeal almonds at -30 minutes (if applicable) and the mixed meal tolerance test at 0 minutes. |
| Cardiometabolic health - fasting glucose | The difference in the change of fasting plasma blood glucose from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting high-density lipoprotein cholesterol | The difference in the change of fasting high-density lipoprotein cholesterol from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting low-density lipoprotein cholesterol | The difference in the change of fasting low-density lipoprotein cholesterol from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting total cholesterol | The difference in the change of fasting total cholesterol from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting insulin | The difference in the change of fasting plasma insulin from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting glucagon-like peptide 1 | The difference in the change of fasting glucagon-like peptide 1 from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - fasting C-reactive protein | The difference in the change of fasting C-reactive protein from before to after a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - 24-hour glucose | The difference in average 24-hour glucose assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - glucose incremental area under the curve | The difference in average meal blood glucose incremental area under the curve (iAUC) assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - glucose area under the curve | The difference in average meal blood glucose area under the curve (AUC) assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - glucose standard deviation | The difference in average blood glucose standard deviation (SD) assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - glucose coefficient of variation | The difference in average blood glucose coefficient of variation (CV) assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| Cardiometabolic health - glucose time in range | The difference in average glucose time in range assessed via CGM during a 10-day controlled feeding diet period with thrice daily premeal ingestion of 18 g of almonds 30 minutes to each meal (MMTT+) compared to without (MMTT-). | Days 5-25 |
| D004700 | Endocrine System Diseases |
| D006946 | Hyperinsulinism |
| D006943 | Hyperglycemia |