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

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

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Gestational Diabetes
• Intervention / Treatment: Other: Almond Snack Intervention for Gestational Diabetes; Other: Control (placebo) group

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.

• Study Type: Interventional
• Enrollment (Estimated): 156
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Sara L White; Phone Number: +44 (0) 20 7188 8151; Email: sara.white@kcl.ac.uk
• Study Contact Backup: Name: Olivia Righton; Email: olivia.k.righton@kcl.ac.uk

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

1. Age over 16 years
2. Singleton pregnancy
3. 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
4. Planned antenatal care at the same centre
5. GDm-Health (a digital app for the management of diabetes in pregnancy) used as part of their management for GDM
6. Willing and able to give informed consent

Exclusion Criteria:

1. Age under 16 years or over 55 years
2. Multiple pregnancy
3. Non-snack consumers
4. Smokers
5. Women who would work night shifts over the study period
6. Women who have already commenced insulin for the treatment of GDM
7. Allergy or intolerance to nuts
8. 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
9. Unwilling or unable to give informed consent

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Almond group; Participants in the almond group will consume 43 g of almonds daily for 28 days, divided into two equal portions: one in the afternoon and one in the evening.	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.
Placebo Comparator: Control group; Participants in the control group will consume nut-free snacks (e.g., crackers or savoury biscuits) that are energy-matched to the almond 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Mean nocturnal blood glucose (22.00-07.00h)	The primary endpoint will be assessed on day 14 and day 28 of the intervention.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean daytime glucose 07.00-22.00h	Recommended glucose control target 3.5-7.8mmol/L, AUC <6.7mmol/L, AUC <7.8mmol/L	Assessed on day 14 and day 28 of the intervention.
Postprandial blood glucose	Mean postprandial blood glucose for 1, 2 & 4 hours after dinner.	Assessed on day 14 and day 28 of the intervention.
Glucose variability	Glucose SD, glucose CV	Assessed on day 14 and 28 of the intervention.
Blood glucose indices	High and low blood glucose indices (HBGI & LBGI)	Assessed on day 14 and 28 of the intervention.
HbA1c	Biochemical analysis of maternal blood	Assessed on day 0 and day 28 of the intervention.
Liver function	Biochemical analysis of maternal blood: gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST)	Assessed on day 0 and day 28 of the intervention.
Maternal metabolome (blood)	Lipid measures, including lipoprotein particles (VLDL subdivided into six subclasses, IDL, LDL subdivided into three subclasses, and HDL subdivided into four subclasses), constituents within each lipoprotein particle type (triglycerides, total cholesterol, free cholesterol and cholesterol ester levels and phospholipid concentrations), fatty acids, amino acids, glycolysis related metabolites, ketone bodies and inflammatory markers.	Assessed on day 0 and day 28 of the intervention.
Maternal weight in kg	Maternal weight and height will be combined to report BMI in kg/m^2	Assessed on day 0 and day 28 of the intervention.
Dietary intake using questionnaire	Assessment of dietary intake using Intake24, a validated digital dietary recall system based on the multiple-pass 24-hour recall	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	Assessment of appetite on a 1-7 Likert scale (i.e., 1 = Not at all hungry, 7 = Extremely hungry)	Assessed on day 0, day 14, and day 28 of the intervention.
Physical activity using accelerometer	The accelerometer will record physical activity, such as average time spent in moderate, low, and sedentary activity	Assessed on days 0-28 of the intervention.
Stool	(Optional) may be collected and stored for microbiome analysis	May be assessed on days 0, 14 and 28 of the intervention.
Sleep quality using accelerometer	The accelerometer will measure sleep quality, such as sleep duration	Assessed on days 0-28 of the intervention.
Course of GDM	If medication is required for glucose control, such as metformin or insulin (dose, time of initiation)	Assessed on days 0-28 of the intervention.
Mode of delivery		Assessed at delivery.
Acceptability of the intervention using questionnaire	A dietary intervention acceptability questionnaire will be used to assess enjoyment, sensory aspects, gastrointestinal effects, palatability, and appetite sensations.	Assessed on day 28 of the intervention.
Birthweight		Assessed at delivery.
Neonatal head circumference		Assessed at delivery.
Neonatal sex		Assessed at delivery.
Gestational age		Assessed at delivery.
Neonatal complications		Assessed at delivery.
Maternal complications		Assessed at delivery.
Labour onset checklist		Assessed at delivery.

Collaborators and Investigators

• Sponsor: Guy's and St Thomas' NHS Foundation Trust
• Collaborators: King's College London; Almond Board of California
• Investigators: Principal Investigator: Sara L White, King's College London

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2025
• Primary Completion (Estimated): October 1, 2025
• Study Completion (Estimated): October 1, 2025

Study Registration Dates

• First Submitted: May 12, 2025
• First Submitted That Met QC Criteria: July 16, 2025
• First Posted (Actual): July 17, 2025

Study Record Updates

• Last Update Posted (Actual): July 17, 2025
• Last Update Submitted That Met QC Criteria: July 16, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: gestational diabetes; dietary intervention; pregnancy nutrition
• Additional Relevant MeSH Terms: Urogenital Diseases; Endocrine System Diseases; Female Urogenital Diseases and Pregnancy Complications; Metabolic Diseases; Pregnancy Complications; Glucose Metabolism Disorders; Diabetes, Gestational; Diabetes Mellitus
• Other Study ID Numbers: 325804

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No