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

N/ANot Yet RecruitingNCT07069855

Guy's and St Thomas' NHS Foundation Trust156 enrolled

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.

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

Allocation

RANDOMIZED

Purpose

TREATMENT

Interventions

Almond Snack Intervention for Gestational DiabetesOTHER

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.

Control (placebo) groupOTHER

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.

Eligibility

Sex: FEMALEMin age: 16 YearsMax age: 55 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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 Outcomes

Mean daytime glucose 07.00-22.00h

Recommended glucose control target 3.5-7.8mmol/L, AUC \<6.7mmol/L, AUC \<7.8mmol/L

Time frame: Assessed on day 14 and day 28 of the intervention.

Postprandial blood glucose

Mean postprandial blood glucose for 1, 2 \& 4 hours after dinner.

Time frame: Assessed on day 14 and day 28 of the intervention.

Glucose variability

Glucose SD, glucose CV

Time frame: Assessed on day 14 and 28 of the intervention.

Blood glucose indices

High and low blood glucose indices (HBGI \& LBGI)

Time frame: Assessed on day 14 and 28 of the intervention.

HbA1c

Biochemical analysis of maternal blood

Time frame: 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)

Time frame: 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.

Time frame: 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

Time frame: 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

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

Assessment of appetite on a 1-7 Likert scale (i.e., 1 = Not at all hungry, 7 = Extremely hungry)

Time frame: 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

Time frame: Assessed on days 0-28 of the intervention.

Stool

(Optional) may be collected and stored for microbiome analysis

Time frame: 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

Time frame: 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)

Time frame: Assessed on days 0-28 of the intervention.

Mode of delivery