Dietary sodium reduction does not affect circulating glucose concentrations in fasting children or adults: findings from a systematic review and meta-analysis.
BACKGROUND
Although evidence shows that reduced sodium intake lowers blood pressure, some studies suggest that sodium reduction may adversely affect insulin resistance and glucose tolerance.


OBJECTIVE
The objectives were to assess the effects of sodium reduction on glucose tolerance, evaluate strengths and weaknesses of the relevant scientific literature, and provide direction for future research.


METHODS
We searched The Cochrane Library, MEDLINE, EMBASE, CINAHL, and Web of Science through August 2014. Both randomized and nonrandomized intervention trials were included in our meta-analyses. The effects of sodium reduction on glucose tolerance were evaluated in 37 articles, but because of a lack of comparable data, 8 trials were excluded from the meta-analyses.


RESULTS
Participants were 10-79 y old, either primarily healthy or with hypertension. In meta-analyses of 20 randomized, crossover trials (n = 504 participants) and 9 nonrandomized crossover trials (n = 337), circulating glucose concentrations of fasting participants were not affected by reduction in sodium intake. In contrast, in meta-analyses of 19 of the 20 randomized, crossover trials (n = 494), fasting insulin concentrations were 9.53 pmol/L higher (95% CI: 5.04, 14.02 pmol/L higher) with sodium reduction. In 9 nonrandomized trials (n = 337), fasting insulin did not differ with reduced sodium intake. Results differed little when the analyses were restricted to studies with a low risk of bias and duration of ≥7 d.


CONCLUSIONS
This meta-analysis revealed no evidence that, in trials with a short intervention and large reductions in sodium, circulating glucose concentrations differed between groups. Recommendations for future studies include extending intervention durations, ensuring comparability of groups at baseline through randomization, and assessing sodium intakes relevant to population sodium reduction. In addition, analyses on other metabolic variables were limited because of the number of trials reporting these outcomes and lack of consistency across measures, suggesting a need for comparable measures of glucose tolerance across studies.
Divisions of Heart Disease and Stroke Prevention and Oak Ridge Institute for Science and Education, Atlanta, GA; and Isp7@cdc.gov.
Sheena M
SM
Patel
Divisions of Heart Disease and Stroke Prevention and.
Paul
P
Cobb
Diabetes Translation, CDC, Atlanta, GA;
Sharon
S
Saydah
Diabetes Translation, CDC, Atlanta, GA;
Xuanping
X
Zhang
NIH, National Heart, Lung, and Blood Institute, Bethesda, MD.
Janet M
JM
de Jesus
Divisions of Heart Disease and Stroke Prevention and.
Mary E
ME
Cogswell
D000293:Adolescent; D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D016208:Databases, Factual; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D012680:Sensitivity and Specificity; D012982:Sodium, Dietary / Q000008:administration & dosage*; D055815:Young Adult
D001786:Blood Glucose; D012982:Sodium, Dietary
fasting glucose; insulin resistance; meta-analysis; sodium reduction; systematic review