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Research Summary
Analyzed using Evidence Intelligence™

Low-Carbohydrate Diet Reduces HbA1c in Prediabetes

Powered by the Dediabetes Evidence Intelligence™ framework

Last updated August 21, 2026

Key finding

Hemoglobin A1c decreased by 0.23% compared with usual diet over 6 months.

This study evaluated the impact of a low-carbohydrate diet on hemoglobin A1c levels in adults with prediabetes, finding significant reductions in several health markers.

Quick read

Study at a glance

The essential study design details in one scan.

EvidenceScore™

Moderate

Study type

RCTs

Follow-up

Medium-Term (3–12 mo)

Risk of bias

Some Concerns

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Plain-language summary

What this paper says

A plain-language read of the study’s main message and where it applies.

Study focus

This study evaluated the impact of a low-carbohydrate diet on hemoglobin A1c levels in adults with prediabetes, finding significant reductions in several health markers.

Clinical relevance

These findings are clinically significant as they suggest that a low-carbohydrate diet may be an effective strategy for improving glycemic control and reducing body weight in adults at risk for type 2 diabetes. By lowering hemoglobin A1c and fasting plasma glucose, this dietary approach could help prevent the progression from prediabetes to diabetes, ultimately reducing the burden of diabetes-related complications.

Keep in mind

The study's sample size may limit the generalizability of the findings. The duration of the study was only six months, which may not capture long-term effects. Potential confounding factors were not fully controlled for in the analysis.

Published in

Journal Reference

Publication details and source links for this paper.

Kirsten SD, Lydia AB, Lu Q, et al. Effect of a Low-Carbohydrate Diet on Hemoglobin A1c Among Adults with Prediabetes. JAMA Network Open. 2022;5(10):e2238645. doi:10.1001/jamanetworkopen.2022.38645

View DOIView on PubMedView on PMC

Main Effects

Hemoglobin A1c decreased by 0.23% (p=0.001) in the low-carbohydrate diet group.

Fasting plasma glucose decreased by 10.3 mg/dL (p=0.001) compared to the usual diet.

Body weight decreased by 5.9 kg (p=0.001) in the low-carbohydrate diet group.

Diastolic blood pressure decreased by 3.2 mm Hg (p=0.05) in the low-carb group.

Evidence network

How this study fits

Understand where this research contributes within the broader evidence network.

Evidence Context

This study contributes evidence to Low-carbohydrate diet and Body weight, Diastolic blood pressure, Fasting Plasma Glucose (FPG), and 2 more.

This study contributes evidence to

Intervention

Low-carbohydrate diet

Outcome

Body weight

Evidence topic

Dietary Patterns

Primary intervention

Low-carbohydrate diet

Primary outcomes

  • Body weight
  • Diastolic blood pressure
  • Fasting Plasma Glucose (FPG)

Evidence topics

Dietary PatternsBlood PressureFasting Blood GlucoseGlycemic Control

Primary intervention

Low-carbohydrate diet

Primary outcomes

Body weightDiastolic blood pressureFasting Plasma Glucose (FPG)

Evidence relationships

Intervention and outcome relationships this study adds to the evidence network.

5
Evidence pairs
5
Relationships
6
Evidence topics
contributes_evidence

Editorial context

Why this study matters

See why this paper is useful beyond its individual results.

Evidence network role

This section describes how the study fits into the current evidence network. It does not determine whether an intervention works on its own.

Moderate contributionModerate confidenceNetwork score: 68

6

Related topics

5

Evidence pairs

2339

Related studies

High relevance in at least one topic

Why it is useful

  • Contributes to 5 evidence relationships
  • Includes primary outcome data
  • Linked to 6 direct semantic evidence topics

Topic contributions

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

Evidence topic

Contributes evidence

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Primary evidence

Evidence relationship

Low-Carbohydrate Diet Education and HbA1c

Related evidence

Evidence relationship

Low-Carbohydrate Diet Education and Body Weight

Save evidence

Evidence relationship

Low-Carbohydrate Diet Education and Blood Pressure

Save evidence

Core evidence

Study findings

The primary outcomes reported in this study.

Body weight

Low-carbohydrate diet → Body weight

Low-carbohydrate diet → Body weight

Evidence Intelligence™
EvidenceScore™
85
Strong
ImpactScore™
90
Very Positive
ConsistencyScore™
78
consistent
Supporting studies: Based on 10 studies
Add to Evidence Tracker

Diastolic blood pressure

Low-carbohydrate diet → Diastolic blood pressure

Low-carbohydrate diet → Diastolic blood pressure

Evidence Intelligence™
EvidenceScore™
Emerging
Score 59 · Based on 1 study
ImpactScore™
50
Neutral
ConsistencyScore™
unclear
Not enough independent studies
Supporting studies: Based on 1 study
Add to Evidence Tracker

Fasting Plasma Glucose (FPG)

Low-carbohydrate diet → Fasting Plasma Glucose (FPG)

Low-carbohydrate diet → Fasting Plasma Glucose (FPG)

Evidence Intelligence™
EvidenceScore™
84
Strong
ImpactScore™
90
Very Positive
ConsistencyScore™
100
consistent
Supporting studies: Based on 5 studies
Add to Evidence Tracker

Reduction in Hemoglobin A1C levels

Low-carbohydrate diet → Reduction in Hemoglobin A1C levels

Low-carbohydrate diet → Reduction in Hemoglobin A1C levels

Evidence Intelligence™
EvidenceScore™
Emerging
Score 59 · Based on 1 study
ImpactScore™
100
Very Positive
ConsistencyScore™
unclear
Not enough independent studies
Supporting studies: Based on 1 study
Add to Evidence Tracker

Systolic blood pressure

Low-carbohydrate diet → Systolic blood pressure

Low-carbohydrate diet → Systolic blood pressure

Evidence Intelligence™
EvidenceScore™
83
Strong
ImpactScore™
80
Positive
ConsistencyScore™
80
consistent
Supporting studies: Based on 5 studies
Add to Evidence Tracker

Evidence Library

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evidence suggest

Evidence Suggest

  • Hemoglobin A1c reduced by 0.23% in the low-carb diet group.
  • Fasting plasma glucose decreased by 10.3 mg/dL after six months.
  • Body weight loss averaged 5.9 kg in participants on the low-carb diet.
who this applies

Who this applies to

  • Adults diagnosed with prediabetes.
  • Individuals seeking dietary interventions for blood sugar management.
keep in mind

Keep in Mind

  • Results may not apply to populations outside the study's demographic.
  • The study did not assess the long-term sustainability of the low-carb diet.
  • Further research is needed to confirm findings in larger, diverse populations.
between the lines

Between the Lines

  • The study's sample size may limit the generalizability of the findings.
  • The duration of the study was only six months, which may not capture long-term effects.
  • Potential confounding factors were not fully controlled for in the analysis.

Evidence Library

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Connected Evidence

Explore related studies, evidence collections, and research questions.

Relationships organized using the Dediabetes Evidence Intelligence™ framework.

Powered by the Dediabetes Evidence Intelligence™ framework

This study contributes to evidence on Low-Carbohydrate Diet Education and Body Weight, Low-Carbohydrate Diet Education and Fasting Glucose.

Related evidence relationships

Explore in Evidence Explorer

This study contributes to the evidence on the following intervention-outcome relationships.

Questions answered by this study

Generated from the study's connected evidence using Evidence Intelligence™.

Does Low-Carbohydrate Diet Education lower HbA1c?

Strong Evidence

Low-Carbohydrate Diet Education may lower HbA1c.

ConsistencyScore™: Results are generally consistent across studies.

Ranked evidence signals

  1. 1

    Reduction in Hemoglobin A1C levels

    EvidenceScore™ Emerging | EvidenceScore™ 59.0 | strong positive | ConsistencyScore™ Unclear | 1 study

Why this answer: This answer is based on 22 supporting studies with generally consistent results and a positive effect signal.

22 supporting studies
View Full Evidence

Does Low-Carbohydrate Diet Education affect body weight?

Strong Evidence

Low-Carbohydrate Diet Education appears to affect body weight.

ConsistencyScore™: Results are consistent across studies.

Ranked evidence signals

  1. 1

    Body weight

    EvidenceScore™ Strong | EvidenceScore™ 85.4 | strong positive | ConsistencyScore™ Consistent | 1 study

Why this answer: This answer is based on 12 supporting studies with consistent results and a positive effect signal.

12 supporting studies
View Full Evidence

Does Low-Carbohydrate Diet Education improve blood pressure?

Strong Evidence

Low-Carbohydrate Diet Education may improve blood pressure.

ConsistencyScore™: Results are consistent across studies.

Ranked evidence signals

  1. 1

    Systolic blood pressure

    EvidenceScore™ Strong | EvidenceScore™ 83.3 | moderate positive | ConsistencyScore™ Consistent | 1 study

  2. 2

    Diastolic blood pressure

    EvidenceScore™ Emerging | EvidenceScore™ 59.0 | neutral | ConsistencyScore™ Unclear | 1 study

Why this answer: This answer is based on 6 supporting studies with consistent results and a positive effect signal.

6 supporting studies
View Full Evidence

Does Low-Carbohydrate Diet Education improve fasting glucose?

Strong Evidence

Low-Carbohydrate Diet Education may improve fasting glucose.

ConsistencyScore™: Results are consistent across studies.

Ranked evidence signals

  1. 1

    Fasting Plasma Glucose (FPG)

    EvidenceScore™ Strong | EvidenceScore™ 84.3 | strong positive | ConsistencyScore™ Consistent | 1 study

Why this answer: This answer is based on 10 supporting studies with consistent results and a positive effect signal.

10 supporting studies
View Full Evidence
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Next steps

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Evidence topics

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Dietary Patterns Evidence HubBlood Pressure Evidence HubFasting Blood Glucose Evidence HubGlycemic Control Evidence Hub

Explore in Evidence Explorer

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All studies on Low-carbohydrate diet and Body weightAll studies on Low-carbohydrate diet and Fasting Plasma Glucose (FPG)All studies on Low-carbohydrate diet and Reduction in Hemoglobin A1C levelsAll studies on Low-carbohydrate diet and Systolic blood pressure

Related research

Read related research summaries.

Carbohydrate restriction lowers HbA1c but not β-cell function in T2DModerate Carbohydrate Diet Improves Glycemic Control in Type 1 DiabetesLow-Carbohydrate Diet Improves Glycemic Control in Adolescents with Type 1 DiabetesLow-Carbohydrate Diet Improves Liver Fat in Type 2 DiabetesLow-carbohydrate diets may improve diabetes control in type 1 diabetes

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