Effects of Almonds on Insulin Sensitivity in Prediabetes

This is a randomized, controlled, two-period crossover study that includes two screening visits, and two 6-week test periods, separated by a 4-week washout. Subjects consume twice daily, 1.5 oz whole, natural almonds (Active Condition) or low-fat foods high in refined starches and added sugars, matched for energy content to the almonds (Control Condition). The assigned study products will be dispensed with instructions to consume 2 servings (Active Product) or 3 servings (Control Products) each day, starting on day 1. Subjects will be screened for prediabetes at the first screening visits. An intravenous glucose tolerance test (IVGTT) will be completed at baseline and the end of each treatment period. Fasting blood samples will be collected for lipid profile and high-sensitivity C-reactive protein (hs-CRP) measurements at all visits. Additionally, blood will be drawn for measurement of Apolipoprotein B and A1, lipoprotein particles and subfractions, Interleukin 6 (IL-6) and Uric acid at the beginning and the end of each test period. Assessments of vital signs, body weight, evaluation of inclusion and exclusion criteria, medication/supplement use, and adverse effects will be performed throughout the study. Compliance will be assessed through a daily log record, and return of unopened study product.

Inclusion criteria

• BMI of 25.0-39.9 kg/m2
• Prediabetic: fingerstick glycated hemoglobin 5.7-6.4% (inclusive), or fasting fingerstick capillary glucose of 100-125 mg/dL (inclusive), or 2-h post-prandial glucose of 140-199 mg/dL.
• Fasting LDL-C level <200 mg/dL and fasting TG level <400 mg/dL.
• Judged to be in general good health on the basis of medical history and screening laboratory tests.

Exclusion criteria

• Atherosclerotic cardiovascular disease including any of the following: clinical signs of atherosclerosis: peripheral arterial disease, abdominal aortic aneurysm, carotid artery disease [symptomatic (e.g., transient ischemic attack or stroke of carotid origin) or >50% stenosis on angiography or ultrasound], history of myocardial infarction, angina, a revascularization procedure, or other forms of clinical atherosclerotic disease (e.g., renal artery disease).
• History or presence of clinically important pulmonary (including uncontrolled asthma), endocrine (including type I or type II diabetes mellitus), chronic inflammatory disease (including irritable bowel disease, lupus, rheumatoid arthritis), hepatic, renal, hematologic, immunologic, dermatologic, neurologic, psychiatric, or biliary disorders.
• Known allergy, sensitivity, or intolerance to any ingredients in the study foods.
• Uncontrolled hypertension.
• Recent history of cancer, except for non-melanoma skin cancer.
• Recent change in body weight of ± 4.5 kg (9.9 lbs).
• Recent use of any medications intended to alter the lipid profile (e.g. bile acid sequestrants, cholesterol absorption inhibitor, fibrates, niacin (drug form), omega-3-ethyl ester drugs, and/or PCSK9 inhibitors, with the exception of the stable use of statins), weight-loss drugs or programs, systemic corticosteroid drugs, unstable use of any antihypertensive medication; medications known to influence CHO metabolism (e.g. adrenergic receptor blockers, diuretics, and/or hypoglycemic medications).
• Recent use of food/supplements known to influence lipid metabolism (e.g. omega-3 fatty acid supplements (e.g., flaxseed, fish or algal oils) or fortified foods, sterol/stanol products; dietary supplements (red rice yeast supplements; garlic supplements; soy isoflavone supplements; niacin or its analogues at doses >400 mg/d, and irregular or inconsistent use of Metamucil® or viscous fiber-containing supplements.
• Recent use of antibiotics.
• Pregnant, planning to be pregnant during the study period, lactating, or is of childbearing potential and is unwilling to commit to the use of a medically approved form of contraception throughout the study period.
• Extreme dietary habits (e.g. very low CHO diet, vegan, etc.).
• Current or recent history, or strong potential, for drug or alcohol abuse.
• History of a diagnosed eating disorder. -