Nutcracker: Can Almond Nut Consumption Improve Nocturnal Glycaemic Control in Women With Gestational Diabetes Mellitus?

Official title

Nutcracker: Can Almond Nut Consumption Improve Nocturnal Glycaemic Control in Women With Gestational Diabetes Mellitus? A Randomised Controlled Trial

Overview

Gestational diabetes, affecting over one in six births globally, is a growing public health concern. Characterised by high blood glucose, it increases the risk of pregnancy complications and raises the mother's long-term risk of type 2 diabetes. Managing high fasting glucose, which reflects elevated overnight levels, is a key challenge. Night-time snacking-more common in women with gestational diabetes-is linked to higher fasting glucose, but the impact of snack quality is unclear. Almonds have been shown to improve glucose control in non-pregnant adults. This study will test whether almonds, as a night-time snack, can improve overnight glucose levels in pregnant women with gestational diabetes. Findings could support a simple, effective dietary strategy to improve outcomes for mothers and babies worldwide.

Detailed description

Gestational diabetes mellitus (GDM) is a significant and increasingly prevalent public health concern, affecting over one-sixth of births globally. A key challenge in its management is fasting hyperglycaemia, which may result from elevated nocturnal glucose concentrations. Nocturnal hyperglycaemia has been linked to an increased risk of large-for-gestational-age infants in women with GDM. These women are also more likely to snack at night, a behaviour associated with higher fasting glucose concentrations; however, the impact of snack quality on overnight glucose regulation remains unclear.

Almond consumption has been shown to improve glycaemia in individuals with prediabetes or type 2 diabetes, potentially through mechanisms such as carbohydrate displacement and the beneficial effects of their nutrient profile, particularly magnesium and monounsaturated fats. Despite this, research in pregnant populations-especially those with GDM-is limited.

This study will investigate whether consuming almonds as an evening snack for four weeks improves overnight glucose regulation in women with GDM. Participants will be randomised to receive either almonds or a nut-free, energy-matched control snack. Changes in glucose metabolism will be assessed to determine the potential role of almonds in dietary management of GDM.

Interventions

• Other Almond Snack Intervention for Gestational Diabetes
  This intervention involves daily consumption of 43 g of whole almonds, split into two portions (afternoon and evening), for 28 days in pregnant women diagnosed with gestational diabetes who habitually consume evening snacks.
• Other Control (placebo) group
  This control involves the daily consumption of a nut-free snack (2 portions) that reflects a 'typical snack' choice among pregnant women with gestational diabetes. It serves as a comparison to assess the specific impact of almond-based evening snacking on overnight glucose regulation.

Primary outcome measures

• Mean nocturnal blood glucose (22.00-07.00h) [Time frame: The primary endpoint will be assessed on day 14 and day 28 of the intervention.]

Secondary outcome measures (12)

• Mean daytime glucose 07.00-22.00h [Time frame: Assessed on day 14 and day 28 of the intervention.]
• Postprandial blood glucose [Time frame: Assessed on day 14 and day 28 of the intervention.]
• Glucose variability [Time frame: Assessed on day 14 and 28 of the intervention.]
• Blood glucose indices [Time frame: Assessed on day 14 and 28 of the intervention.]
• HbA1c [Time frame: Assessed on day 0 and day 28 of the intervention.]
• Liver function [Time frame: Assessed on day 0 and day 28 of the intervention.]
• Maternal metabolome (blood) [Time frame: Assessed on day 0 and day 28 of the intervention.]
• Maternal weight in kg [Time frame: Assessed on day 0 and day 28 of the intervention.]
• Dietary intake using questionnaire [Time frame: Assessed on or around day 0 (x2), day 14 (x 2) and day 28 (x2) of the intervention.]
• Assessment of appetite on a Likert scale [Time frame: Assessed on day 0, day 14, and day 28 of the intervention.]
• Physical activity using accelerometer [Time frame: Assessed on days 0-28 of the intervention.]
• Stool [Time frame: May be assessed on days 0, 14 and 28 of the intervention.]

Eligibility criteria

Inclusion criteria

• Age over 16 years
• Singleton pregnancy
• 25 to 31+6 weeks' gestation diagnosed with GDM using a standard clinical 75g oral glucose tolerance test (OGTT), as per the guidelines of the National Institute of Health and Care Excellence (NICE), and had their first post-diagnosis consultation (approx. 7-10 days later). The NICE criteria state that the diagnosis of GDM will be made with one or more glucose concentrations during the OGTT of >5.6 mmol/l in the fasting state; >7.8 mmol/l 2 hours after 75g glucose
• Planned antenatal care at the same centre
• GDm-Health (a digital app for the management of diabetes in pregnancy) used as part of their management for GDM
• Willing and able to give informed consent

Exclusion criteria

• Age under 16 years or over 55 years
• Multiple pregnancy
• Non-snack consumers
• Smokers
• Women who would work night shifts over the study period
• Women who have already commenced insulin for the treatment of GDM
• Allergy or intolerance to nuts
• Pre-existing medical conditions, including Type 1 or Type 2 diabetes, chronic coronary, renal or bowel disease or history of cholestatic liver disease or pancreatitis. Presence of gastrointestinal disorder or use of a drug which is likely to alter gastrointestinal motility or nutrient absorption, previous bariatric surgery
• Unwilling or unable to give informed consent

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Treatment

Study locations

Center list to be confirmed — check the primary protocol.

Identifiers

NCT: NCT07069855 · 325804

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗