Glycaemic Index, Glycaemic Load, and Type 2 Diabetes: Insights from the PURE Study
Unveiling the Link Between Diet and Diabetes: The PURE Study reveals how high glycemic index (GI) and glycemic load (GL) diets can increase your risk of type 2 diabetes. Discover how to lower your risk through dietary choices based on scientific evidence.
DR T S DIDWAL MD
6/3/20246 min read
The PURE study published in Lancet. Diabetes & endocrinology investigated the link between dietary glycemic index (GI) and glycemic load (GL) and type 2 diabetes risk in over 127,000 adults from 20 countries. Those with high-GI diets had a 15% increased risk, while high-GL diets were linked to a 21% increase. This risk was stronger in people with a higher BMI. The findings suggest that consuming low-GI and low-GL diets could be an effective strategy to prevent type 2 diabetes, especially for those with a higher BMI. Public health guidelines should emphasize these dietary patterns.
Key Points
Large and Diverse Cohort:
The study included 127,594 adults aged 35–70 from 20 countries, representing high-income, middle-income, and low-income regions, making the findings broadly applicable across diverse populations.
Long Follow-Up Period:
Participants were followed for a median of 11.8 years (IQR 9.0–13.0 years), providing a robust timeframe to assess the long-term impact of dietary glycaemic index (GI) and glycaemic load (GL) on type 2 diabetes incidence.
Significant Association with High Glycaemic Index:
Diets with a higher glycaemic index were significantly associated with a higher risk of developing type 2 diabetes. Participants in the highest quintile of GI had a 15% higher risk compared to those in the lowest quintile
Increased Risk with High Glycaemic Load:
Similarly, a higher glycaemic load was associated with a 21% increased risk of type 2 diabetes. Participants in the highest quintile of GL had a significantly higher risk compared to those in the lowest quintile
Stronger Association in Individuals with Higher BMI:
The association between high GI and diabetes risk was more pronounced in individuals with a higher BMI. For these individuals, the risk increased by 23% , compared to a weaker and not statistically significant association in those with a lower BMI.
Consistent Findings Across Regions and Incomes:
The associations between high GI/GL and type 2 diabetes were consistent across different geographic regions and income levels, underscoring the global relevance of the findings.
Implications for Dietary Guidelines:
The study suggests that consuming low-GI and low-GL diets could be an effective strategy for preventing type 2 diabetes, particularly among individuals with a higher BMI. Public health guidelines should emphasize the importance of low-GI and low-GL foods to mitigate the risk of type 2 diabetes.
Understanding the Impact of Glycaemic Index and Glycaemic Load on Type 2 Diabetes: Insights from the PURE Study
The global prevalence of type 2 diabetes has reached epidemic proportions, necessitating a closer examination of dietary factors that contribute to its development. The PURE (Prospective Urban Rural Epidemiology) study, provides significant insights into the relationship between dietary glycaemic index (GI), glycaemic load (GL), and the risk of type 2 diabetes across diverse populations.
The Glycaemic Index and Glycaemic Load: Key Concepts
Before delving into the study's findings, it’s crucial to understand the concepts of glycaemic index and glycaemic load. The glycaemic index measures how quickly foods containing carbohydrates raise blood glucose levels. Foods with a high GI cause a rapid spike in blood glucose, while those with a low GI result in a slower, more gradual increase. Glycaemic load takes into account both the quality (GI) and quantity of carbohydrates in a food item, providing a more comprehensive picture of its impact on blood sugar levels.
The PURE Study: Scope and Methodology
The PURE study is a large-scale, multinational cohort study that included 127,594 adults aged 35–70 years from 20 countries, representing high, middle, and low-income regions. This diverse cohort allowed for a robust analysis of dietary patterns across different cultural and socioeconomic contexts. Participants' diets were assessed using country-specific, validated food frequency questionnaires at baseline. The glycaemic index and glycaemic load were calculated based on the intake of seven categories of carbohydrate-containing foods.
Participants were divided into quintiles based on their dietary GI and GL. The primary outcome of interest was the incidence of type 2 diabetes, monitored over a median follow-up period of 11.8 years.
Key Findings
The study reported 7,326 (5.7%) incident cases of type 2 diabetes during the follow-up period. The analysis revealed a significant association between high dietary GI and GL and an increased risk of developing type 2 diabetes.
Glycemic Index and Type 2 Diabetes Risk:
Highest Quintile vs. Lowest Quintile of GI:
Hazard Ratio (HR): 1.15 (95% Confidence Interval [CI] 1.03–1.29)
Interpretation: Participants in the highest quintile of dietary GI had a 15% higher risk of developing type 2 diabetes compared to those in the lowest quintile.
Effect of BMI:
Higher BMI (quintile 5 vs. quintile 1): HR 1.23 (95% CI 1.08–1.41)
Lower BMI (quintile 5 vs. quintile 1): HR 1.10 (95% CI 0.87–1.39)
P interaction: 0.030
Interpretation: The association between high GI and diabetes risk was stronger among individuals with a higher BMI. Those with higher BMI had a 23% increased risk, while the association was weaker and not statistically significant in individuals with lower BMI.
Glycaemic Load and Type 2 Diabetes Risk:
Highest Quintile vs. Lowest Quintile of GL:
Hazard Ratio (HR): 1.21 (95% CI: 1.06–1.37)
Interpretation: Participants in the highest quintile of dietary GL had a 21% higher risk of developing type 2 diabetes compared to those in the lowest quintile.
Subgroup Analysis
The study conducted subgroup analyses to examine whether the associations between dietary GI/GL and type 2 diabetes varied by different participant characteristics such as BMI, age, sex, and geographic region. Key points from these analyses include:
BMI Interaction: As mentioned, the association between high dietary GI and diabetes risk was significantly modified by BMI, with stronger associations observed in individuals with higher BMI.
Geographic and Income Variation: The associations were consistent across various geographic regions and income levels, indicating that the findings are broadly applicable to diverse populations.
Implications for Public Health and Dietary Guidelines
The results of the PURE study have significant implications for public health and dietary guidelines. They suggest that reducing the glycaemic index and glycaemic load of diets could be a viable strategy for preventing type 2 diabetes, particularly in individuals with higher BMI. This can be achieved by promoting the consumption of low-GI foods such as whole grains, legumes, fruits, and non-starchy vegetables, and by limiting high-GI foods like refined grains, sugary beverages, and processed snacks.
Practical Recommendations
For individuals seeking to lower their risk of type 2 diabetes, the following dietary adjustments can be beneficial:
Choose Whole Grains Over Refined Grains: Whole grains such as oats, barley, and quinoa have a lower GI compared to refined grains like white bread and white rice.
Incorporate Legumes: Beans, lentils, and chickpeas are excellent low-GI options that also provide essential nutrients and fiber.
Opt for Non-Starchy Vegetables: Vegetables like spinach, broccoli, and bell peppers have a minimal impact on blood glucose levels and are packed with vitamins and minerals.
Limit Sugary Beverages: Beverages sweetened with sugar, such as soda and fruit juices, have a high GI and should be consumed sparingly.
Snack Wisely: Choose low-GI snacks like nuts, seeds, and yoghurt instead of high-GI options like cookies and chips.
Conclusion
The PURE study provides compelling evidence that diets with high glycaemic index and glycaemic load are associated with an increased risk of type 2 diabetes. This relationship is particularly significant among individuals with a higher BMI, suggesting that weight management and dietary quality are crucial components of diabetes prevention strategies. By adopting a diet that prioritizes low-GI and low-GL foods, individuals can potentially reduce their risk of developing type 2 diabetes, thereby improving their overall health and well-being.
As the global burden of diabetes continues to rise, these findings highlight the need for public health initiatives and dietary guidelines that promote the consumption of low-GI and low-GL foods. Further research is needed to explore the mechanisms underlying the observed associations and to develop targeted interventions for different population groups. In the meantime, individuals and healthcare providers can take proactive steps to incorporate these dietary recommendations into daily practice, paving the way for a healthier future.
Journal Reference
Miller, V., Jenkins, D. A., Dehghan, M., Srichaikul, K., Rangarajan, S., Mente, A., Mohan, V., Swaminathan, S., Ismail, R., Luz Diaz, M., Ravindran, R. M., Zatonska, K., Bahonar, A., Altuntas, Y., Khatib, R., Lopez-Jaramillo, P., Yusufali, A., Yeates, K., Chifamba, J., Iqbal, R., … Prospective Urban and Rural Epidemiology (PURE) study investigators (2024). Associations of the glycaemic index and the glycaemic load with risk of type 2 diabetes in 127 594 people from 20 countries (PURE): a prospective cohort study. The lancet. Diabetes & endocrinology, 12(5), 330–338. https://doi.org/10.1016/S2213-8587(24)00069-X
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The information on this website is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read on this website
Disclaimer
The information on this website is for informational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read on this website