Researchers studied over 57,000 Korean adults to understand how much salt they ate and whether it connected to prediabetes—a condition where blood sugar levels are higher than normal but not yet diabetic. They found that people eating the most salt had a 33% chance of having prediabetes, compared to just 23% for those eating the least salt. The connection stayed strong even after accounting for weight, age, and other health factors. The study suggests that keeping salt intake moderate—below 3-4 grams per day—might help prevent prediabetes alongside other healthy habits.

The Quick Take

  • What they studied: Whether eating too much salt increases the chances of developing prediabetes in Korean adults
  • Who participated: 57,165 Korean adults without diabetes, tracked between 2010 and 2018 through national health surveys. Participants ranged from underweight to overweight individuals of various ages
  • Key finding: People eating the most salt (over 6.2 grams per day) were 45% more likely to have prediabetes than those eating the least salt (1.4 grams or less per day). The risk was highest for people eating 3-4 grams of salt daily
  • What it means for you: If you eat a lot of salt, you may want to reduce your intake to help prevent prediabetes. This is especially important if you already have high blood pressure or other heart risk factors. However, this study shows connection, not proof that salt causes prediabetes

The Research Details

This was a cross-sectional study, which means researchers looked at a large group of people at one point in time and compared their salt eating habits to their health status. The researchers used data from the Korea National Health and Nutrition Examination Survey collected over 9 years (2010-2018), which is like a giant health checkup program for Korean citizens.

Participants reported everything they ate in the previous 24 hours, and researchers calculated how much salt they consumed. Doctors then tested their blood sugar levels to see who had prediabetes. The researchers used statistical tools to see if higher salt intake was connected to higher prediabetes rates, while accounting for other factors like weight, age, smoking, and existing health conditions.

The study looked at salt intake in different groups—from the lowest eaters to the highest—to see if there was a pattern. They also used advanced statistical methods to map out exactly how risk changed as salt intake increased.

This research approach is important because it uses real-world data from a huge, representative sample of the Korean population rather than just a small group. By following people over 9 years, researchers could see trends in how salt consumption changed and how it related to prediabetes. The study’s large size makes the findings more reliable and applicable to the general population

Strengths: This study included over 57,000 people, making it very large and statistically powerful. The data came from an official national health survey, so it’s reliable and representative of the Korean population. Researchers adjusted for many other factors that could affect the results. Limitations: This is a snapshot study, so it shows connection but cannot prove that salt causes prediabetes. People reported their own food intake, which can be inaccurate. The findings may be most relevant to Korean populations and may differ in other ethnic groups

What the Results Show

The main finding was clear: people who ate more salt had higher rates of prediabetes. In the group eating the least salt (1.4 grams or less per day), about 23% had prediabetes. In the group eating the most salt (over 6.2 grams per day), about 33% had prediabetes—a 10 percentage point difference.

When researchers looked at the World Health Organization’s recommended salt limit of 2 grams per day, people eating more than this amount were 45% more likely to have prediabetes in the initial analysis. Even after accounting for weight, age, blood pressure, cholesterol, and smoking status, people eating more than 2 grams of salt daily still had 15% higher odds of prediabetes.

Interestingly, the risk didn’t increase in a straight line. Instead, it peaked around 3-4 grams of salt per day and then leveled off. This suggests there’s a threshold where salt becomes particularly problematic for blood sugar control.

The study also found that potassium intake didn’t explain the salt-prediabetes connection, meaning the effect was specifically about sodium, not about the balance with other minerals.

When researchers looked at different weight groups separately, they found different patterns. In underweight people, the risk increased steadily with more salt. In overweight people, the pattern was U-shaped—meaning both very low and very high salt intake showed increased risk, with the lowest risk in the middle range. This suggests that body weight may affect how salt influences blood sugar control. Additionally, the study found that average salt intake in Korea declined from 3.8 grams per day in 2010 to 2.7 grams per day in 2018, showing that public health efforts to reduce salt may be working

Previous research has clearly linked high salt intake to high blood pressure and heart disease. This study adds new information by showing that salt may also affect blood sugar control and prediabetes risk. The findings align with smaller studies suggesting salt can interfere with how the body handles glucose. However, most previous research focused on Western populations, so this study is valuable for understanding how salt affects Asian populations specifically

This study shows that salt intake and prediabetes are connected, but it cannot prove that salt causes prediabetes—only that they occur together. People reported their own food intake from memory, which can be inaccurate. The study was done in Korea, so results may not apply equally to other countries or ethnic groups. The study couldn’t account for all possible factors that might influence prediabetes risk. Additionally, because this is a snapshot in time, we don’t know if the same people who ate more salt later developed prediabetes

The Bottom Line

Based on this research, moderating salt intake—aiming for below 3-4 grams per day—appears beneficial for blood sugar control. This aligns with existing recommendations to limit salt for heart health. Confidence level: Moderate. The evidence suggests a connection, but more research is needed to confirm that reducing salt actually prevents prediabetes. Combine salt reduction with other proven strategies like regular exercise, maintaining a healthy weight, and eating plenty of vegetables and whole grains

This finding is most relevant to Korean adults and possibly other Asian populations. Anyone with risk factors for prediabetes—such as family history of diabetes, overweight status, high blood pressure, or high cholesterol—should pay special attention. People already diagnosed with prediabetes may benefit from reducing salt intake. Those with normal blood sugar levels can use this as motivation to keep salt intake moderate as a preventive measure. People with certain kidney conditions should consult their doctor before making major dietary changes

Don’t expect overnight results. Blood sugar control typically improves over weeks to months of consistent salt reduction. Most people would need to maintain lower salt intake for at least 3-6 months to see meaningful changes in blood sugar levels. The benefits accumulate over time, so consistency matters more than perfection

Want to Apply This Research?

  • Track daily sodium intake in milligrams (aim for under 2,000-2,300 mg per day, or about 5-6 grams of salt). Log sodium from packaged foods, restaurant meals, and added salt. Compare weekly averages to identify high-sodium days and patterns
  • Start by identifying your highest-sodium foods and finding lower-sodium alternatives. Reduce added salt gradually so your taste buds adjust. Use the app to set a daily sodium goal and get alerts when approaching your limit. Track which meals and foods contribute most to your sodium intake, then swap them for lower-sodium versions
  • Check your sodium intake weekly and monthly trends. If you have access to blood sugar testing, monitor fasting glucose or HbA1c levels every 3 months to see if salt reduction correlates with improvements. Combine sodium tracking with weight and blood pressure monitoring to see the full picture of your health changes

This research shows a connection between salt intake and prediabetes but does not prove that salt causes prediabetes. Individual responses to dietary changes vary. If you have prediabetes, diabetes, kidney disease, or high blood pressure, consult your healthcare provider before making significant dietary changes, especially regarding sodium restriction. This information is for educational purposes and should not replace professional medical advice. Always discuss dietary modifications with your doctor or registered dietitian, particularly if you take medications that affect sodium or potassium balance.