Balanced Fat Intake Links With Less Type 2 Diabetes

Marlene Busko, for Medscape

October 03, 2022

Researchers published the study covered in this summary on Preprints with The Lancet as a preprint that has not yet been peer reviewed.

Key Takeaways

  • Adults in China who consumed a "balanced," moderate-ratio (middle three quintiles) of animal-to-vegetable cooking oil had a lower rate of developing type 2 diabetes during a median follow-up of 8.6 years compared with those who consumed the lowest ratio (first quintile), after multivariable adjustment using prospectively collected data.

  • The results also indicate that increasing animal cooking oil (such as lard, tallow, or butter) and vegetable cooking oil (such as peanut or soybean oil) consumption were each positively associated with a higher rate of developing type 2 diabetes.

  • Those who consumed the highest ratio (fifth quintile) of animal-to-vegetable cooking oil had a nonsignificant difference in their rate of developing type 2 diabetes compared with those in the first quintile.

Why This Matters

  • The findings suggest that consuming a diet with a "balanced" moderate intake of animal and vegetable oil might lower the risk of type 2 diabetes, which would reduce disease burden and healthcare expenditures.

  • The results imply that using a single source of cooking oil, either animal or vegetable, contributes to the incidence of type 2 diabetes.

  • This is the first large epidemiological study showing a relationship between the ratio of animal- and vegetable-derived fats in people's diets and their risk for incident type 2 diabetes.

Study Design

  • The researchers used data collected prospectively starting in 2010-2012 from 7274 adult residents of Guizhou province, China, with follow-up assessment in 2020 after a median of 8.6 years.

  • At baseline, participants underwent an oral glucose tolerance test and provided information on demographics, family medical history, and personal medical history, including whether they had been diagnosed with type 2 diabetes or were taking antihyperglycemic medications. The study did not include anyone with a history of diabetes.

  • Data on intake of animal and vegetable cooking oil came from a dietary questionnaire.

  • The authors calculated hazard ratios for development of type 2 diabetes after adjusting for multiple potential confounders.  

Key Results

  • The study cohort averaged 44 years old, and 53% were women.

  • During a median follow-up of 8.6 years, 747 people developed type 2 diabetes.

  • Compared with those who had the lowest intake of animal cooking oil (first quintile), those with the highest intake (fifth quintile) had a significant 28% increased relative rate for developing type 2 diabetes after adjustment for several potential confounders.

  • Compared with those with the lowest intake of vegetable cooking oil, those with the highest intake had a significant 56% increased rate of developing type 2 diabetes after adjustment.

  • Compared with adults with the lowest animal-to-vegetable cooking oil ratio (first quintile), those in the second, third, and fourth quintiles for this ratio had significantly lower adjusted relative rates of developing type 2 diabetes, with adjusted hazard ratios of 0.79, 0.65, and 0.68, respectively. Those in the highest quintile(fifth quintile) did not have a significantly different risk compared with the first quintile.

  • The protective effect of a balanced ratio of animal-to-vegetable cooking oils was stronger in people who lived in rural districts and in those who had obesity.


  • The dietary information came from participants' self-reports, which may have produced biased data.

  • The study only included information about animal and vegetable cooking oil consumed at home.

  • There may have been residual confounding from variables not included in the study.

  • The time of diagnosis of type 2 diabetes may have been inaccurate because follow-up occurred only once. 

  • The study may have underestimated the incidence of type 2 diabetes due to lack of information about A1c levels at follow-up.


  • The study did not receive commercial funding.

  • The authors reported no financial disclosures.

This is a summary of a preprint article "The consumption ratio of animal cooking oil to vegetable cooking oil and reduced risk of type 2 diabetes mellitus: A prospective cohort study in Southwest China" written by researchers primarily from Zunyi Medical University, China, on Preprints with The Lancet provided to you by Medscape. This study has not yet been peer reviewed. The full text of the study can be found on


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.