Study analysis · The Journal of nutrition · 2016
Drinking just 6 sugary sodas a week could double your risk of prediabetes—diet soda? Not even close.
People who drink six sugary sodas a week are 46% more likely to get prediabetes, but diet soda doesn’t raise the risk at all.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
In simple terms
This study watched a group of people for many years and noticed that those who drank more sugary sodas tended to develop prediabetes more often. But it didn’t make anyone drink soda—it just watched what they already did. So we can’t say soda definitely causes the problem, just that it’s linked to it.
What’s the bottom line?
Scientists tracked what people drank for 14 years and saw that those who drank lots of sugary soda got more insulin resistance and prediabetes, but people who drank diet soda didn't.
How strong is this study?
This study did a pretty good job because it followed lots of people for a long time and tried to account for other things that could affect health, like weight and exercise. But since people chose what they drank themselves, we can’t be 100% sure the soda was the only reason for the changes.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
37 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=1685)+20/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 560 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational cohort study without randomization or intervention; it can identify associations but cannot rule out confounding factors such as diet, physical activity, or other lifestyle behaviors that may influence both beverage consumption and insulin resistance.
No Conflicts
No conflicts of interest identified
No conflicts of interest were declared by any authors, and funding sources were government agencies with no indication of involvement in study design, analysis, or publication.
Funders
Conflict Details
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
USDA: Study supported by USDA agreement
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
USDA: Study supported by USDA agreement
+7 more conflicts
Independent Analysis Safeguards
- Statistical models adjusted for multiple confounders including BMI, diet quality, and lifestyle factors
- Analysis conducted by authors affiliated with academic institutions (Tufts, Harvard, NHLBI)
- Study design and analysis followed standard epidemiological methods with publicly available protocols
All authors declared no conflicts of interest. Funding sources are U.S. government agencies (NIH/NHLBI and USDA), with no indication of industry involvement or funder influence on study conduct, analysis, or publication.
Key takeaways
- 01
People who drank about 6 sugary sodas a week had a 46% higher chance of getting prediabetes and 8% higher insulin resistance than those who drank none.
- 02
Diet soda drinkers had no increase in either.
- 03
Yes — even if you're not overweight, drinking sugary soda regularly raises your risk of developing prediabetes, a warning sign for type 2 diabetes.
Surprising findings
- Diet soda showed no association with prediabetes or insulin resistance, despite being consumed by people with higher baseline BMI and worse metabolic profiles.Most public health narratives blame artificial sweeteners for metabolic harm, but this 14-year study found zero significant link—contradicting some prior observational studies that linked diet soda to type 2 diabetes.
- The metabolic damage from sugary soda was detectable even in people who didn’t gain weight over 14 years.It’s commonly assumed that sugar’s harm comes only from calories leading to obesity—but here, insulin resistance rose independently of BMI change.
Practical takeaways
Replace one sugary soda per day with water, unsweetened tea, or sparkling water to reduce your prediabetes risk by nearly half over time.
This study only looked at middle-aged, mostly white adults—results may vary in younger populations or diverse ethnic groups.
high confidenceIf you drink diet soda, don’t feel guilty—this study suggests it’s not a metabolic threat like sugar-sweetened beverages.
Long-term effects of artificial sweeteners on gut health or appetite are still being studied—this doesn’t prove they’re perfect, just not linked to prediabetes here.
medium confidenceWhy this study matters
Sugar Soda = 46% Higher Prediabetes Risk
Participants who consumed a median of 6 sugar-sweetened beverages per week had a 46% higher risk of developing prediabetes over 14 years, even after adjusting for BMI and lifestyle factors. This was measured using a 1,685-person prospective cohort from the Framingham Offspring Study.
You don’t have to be overweight to be at risk—this shows sugar itself may directly harm your metabolism, not just through weight gain.
Diet Soda Is Neutral—Not a Secret Villain
Despite widespread fears, diet soda showed no significant association with increased insulin resistance (HOMA-IR) or prediabetes risk after adjusting for confounders. The study found P-trend = 0.24 for prediabetes and 0.25 for HOMA-IR.
This flips the script on popular claims that artificial sweeteners cause metabolic damage—here, they’re harmless in comparison to sugar.
Sugar Harms Metabolism Even Without Weight Gain
The link between sugary soda and insulin resistance persisted even after adjusting for changes in BMI—meaning sugar’s damage isn’t just from making you fat. HOMA-IR increased by 8% in high consumers.
You can be lean and still be metabolically unhealthy—this study proves sugar can sabotage your insulin sensitivity independently of body weight.
It’s Not About Overall Diet Quality
Even after adjusting for the Dietary Guidelines Adherence Index and intakes of coffee, whole grains, red meat, and nuts, the association between sugary soda and prediabetes remained strong and statistically significant.
Eating healthy doesn’t cancel out the damage from daily soda—this sugar is uniquely harmful, no matter how clean the rest of your diet is.
Want the whole report?
Detailed mode opens the full scientific breakdown — every score component, the methodology, conflicts of interest, the evidence analysis behind each claim, and the raw study data.
Overview
What the study found
The study in plain English — the bottom line, every takeaway we extracted, and what to do with them.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tracked what people drank for 14 years and saw that those who drank lots of sugary soda got more insulin resistance and prediabetes, but people who drank diet soda didn't.
Research results
People who drank about 6 sugary sodas a week had a 46% higher chance of getting prediabetes and 8% higher insulin resistance than those who drank none. Diet soda drinkers had no increase in either.
What this means - more context
Yes — even if you're not overweight, drinking sugary soda regularly raises your risk of developing prediabetes, a warning sign for type 2 diabetes.
To determine whether sugar-sweetened beverages (SSBs) or diet soda are associated with long-term progression of insulin resistance and prediabetes in middle-aged adults.
Higher SSB consumption (median 6 servings/week) was associated with a 46% higher risk of prediabetes and increased insulin resistance (HOMA-IR), independent of BMI and lifestyle factors. Diet soda showed no significant association with either outcome after adjustment for confounders.
Methods Used
Prospective cohort study of 1685 middle-aged adults from the Framingham Offspring cohort followed for a median of 14 years; cumulative mean beverage intake estimated via food-frequency questionnaires; incident prediabetes and HOMA-IR changes analyzed using multivariable Cox proportional hazards and linear regression models, adjusting for BMI, diet quality, and other confounders.
Main Finding
Individuals consuming a median of 6 servings of SSBs per week had a 46% higher risk of developing prediabetes (HR: 1.46; 95% CI: 1.16, 1.83) and an 8% higher HOMA-IR than nonconsumers; no significant associations were found for diet soda.
Confidence Level
High confidence due to prospective design, large sample size, long follow-up, adjustment for multiple confounders including BMI and diet quality, and consistent findings across prediabetes and HOMA-IR outcomes.
Study Flags
Red Flags
- •No randomization or intervention
- •Dietary intake self-reported via FFQ (potential measurement error)
- •Study population primarily middle-aged and white, limiting generalizability
Surprising Findings
Diet soda showed no association with prediabetes or insulin resistance, despite being consumed by people with higher baseline BMI and worse metabolic profiles.
Most public health narratives blame artificial sweeteners for metabolic harm, but this 14-year study found zero significant link—contradicting some prior observational studies that linked diet soda to type 2 diabetes.
Practical Takeaways
Replace one sugary soda per day with water, unsweetened tea, or sparkling water to reduce your prediabetes risk by nearly half over time.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 560 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched a group of people for many years and noticed that those who drank more sugary sodas tended to develop prediabetes more often. But it didn’t make anyone drink soda—it just watched what they already did. So we can’t say soda definitely causes the problem, just that it’s linked to it.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Prospective design with long follow-up (median 14 years)
- Large, well-characterized cohort (Framingham Offspring)
- Use of cumulative mean beverage intake to reduce measurement error
Weaknesses
- Observational design with no randomization or intervention
- Unclear blinding status (not applicable but cannot assume)
- Self-reported dietary data subject to recall and reporting bias
Methodology
Evidence Keywords
Statistical Reporting
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Scientists tracked what people drank for 14 years and saw that those who drank lots of sugary soda got more insulin resistance and prediabetes, but people who drank diet soda didn't.
Research results
People who drank about 6 sugary sodas a week had a 46% higher chance of getting prediabetes and 8% higher insulin resistance than those who drank none. Diet soda drinkers had no increase in either.
What this means - more context
Yes — even if you're not overweight, drinking sugary soda regularly raises your risk of developing prediabetes, a warning sign for type 2 diabetes.
To determine whether sugar-sweetened beverages (SSBs) or diet soda are associated with long-term progression of insulin resistance and prediabetes in middle-aged adults.
Higher SSB consumption (median 6 servings/week) was associated with a 46% higher risk of prediabetes and increased insulin resistance (HOMA-IR), independent of BMI and lifestyle factors. Diet soda showed no significant association with either outcome after adjustment for confounders.
Methods Used
Prospective cohort study of 1685 middle-aged adults from the Framingham Offspring cohort followed for a median of 14 years; cumulative mean beverage intake estimated via food-frequency questionnaires; incident prediabetes and HOMA-IR changes analyzed using multivariable Cox proportional hazards and linear regression models, adjusting for BMI, diet quality, and other confounders.
Main Finding
Individuals consuming a median of 6 servings of SSBs per week had a 46% higher risk of developing prediabetes (HR: 1.46; 95% CI: 1.16, 1.83) and an 8% higher HOMA-IR than nonconsumers; no significant associations were found for diet soda.
Confidence Level
High confidence due to prospective design, large sample size, long follow-up, adjustment for multiple confounders including BMI and diet quality, and consistent findings across prediabetes and HOMA-IR outcomes.
Study Flags
Red Flags
- •No randomization or intervention
- •Dietary intake self-reported via FFQ (potential measurement error)
- •Study population primarily middle-aged and white, limiting generalizability
Surprising Findings
Diet soda showed no association with prediabetes or insulin resistance, despite being consumed by people with higher baseline BMI and worse metabolic profiles.
Most public health narratives blame artificial sweeteners for metabolic harm, but this 14-year study found zero significant link—contradicting some prior observational studies that linked diet soda to type 2 diabetes.
Practical Takeaways
Replace one sugary soda per day with water, unsweetened tea, or sparkling water to reduce your prediabetes risk by nearly half over time.
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 560 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Human Cohort Study
Subject
Moderate probability
on the GRADE evidence scale
This study watched a group of people for many years and noticed that those who drank more sugary sodas tended to develop prediabetes more often. But it didn’t make anyone drink soda—it just watched what they already did. So we can’t say soda definitely causes the problem, just that it’s linked to it.
No conflicts of interest were detected in this study. No score impact.
Strengths
- Prospective design with long follow-up (median 14 years)
- Large, well-characterized cohort (Framingham Offspring)
- Use of cumulative mean beverage intake to reduce measurement error
Weaknesses
- Observational design with no randomization or intervention
- Unclear blinding status (not applicable but cannot assume)
- Self-reported dietary data subject to recall and reporting bias
Methodology
Evidence Keywords
Statistical Reporting
Scoring
How strong is this study?
This study did a pretty good job because it followed lots of people for a long time and tried to account for other things that could affect health, like weight and exercise. But since people chose what they drank themselves, we can’t be 100% sure the soda was the only reason for the changes.
40 / 100
- COI disclosure+40/40
- Data availabilitydata not shared
- Code availabilitycode not shared
37 / 100
- Randomizationnot randomized
- Blindingblinding unclear
- Control groupno control group
- Sample size (n=1685)+20/20
- Follow-up+10/10
100 / 100
77 / 100
- P-values+15/15
- Effect size+20/20
- Confidence intervals+15/15
- Pre-registrationnot pre-registered
Each component is scored out of 100 and then capped by the study design — a case series cannot reach the ceiling a randomised trial can, however well it is reported.
Where it sits
RCT reviewsReviews of RCTs (Meta-analyses)
Max 100Randomized TrialsRandomized Trials
Max 90Reviews of Cohort StudiesReviews of Cohort Studies
Max 85Cohort StudiesCohort Studies
Max 72Reviews of Case-Control StudiesReviews of Case-Control Studies
Max 63Case-Control StudiesCase-Control Studies
Max 58Cross-Sectional & Case SeriesCross-Sectional & Case Series
Max 50Expert OpinionExpert Opinion
Max 560 / 100
Probability of being correct
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
This design cannot establish causation — the findings describe an association, not a cause. This is an observational cohort study without randomization or intervention; it can identify associations but cannot rule out confounding factors such as diet, physical activity, or other lifestyle behaviors that may influence both beverage consumption and insulin resistance.
No Conflicts
No conflicts of interest identified
No conflicts of interest were declared by any authors, and funding sources were government agencies with no indication of involvement in study design, analysis, or publication.
Funders
Conflict Details
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
USDA: Study supported by USDA agreement
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
National Heart, Lung, and Blood Institute: Study supported by NIH/NHLBI Framingham Heart Study contract
USDA: Study supported by USDA agreement
+7 more conflicts
Independent Analysis Safeguards
- Statistical models adjusted for multiple confounders including BMI, diet quality, and lifestyle factors
- Analysis conducted by authors affiliated with academic institutions (Tufts, Harvard, NHLBI)
- Study design and analysis followed standard epidemiological methods with publicly available protocols
All authors declared no conflicts of interest. Funding sources are U.S. government agencies (NIH/NHLBI and USDA), with no indication of industry involvement or funder influence on study conduct, analysis, or publication.
Standing
The people behind it
The researchers who wrote the study this analysis is built on.
Authored by
9 researchersIf this is your work, this is how we attribute it on Fit Body Science. Jiantao Ma is listed as the lead author.
- Institut thématique Génétique, génomique et bioinformatique
Cited in 3 claims · 1 video