Plant-based low-carbohydrate diet linked to 24% lower mortality in people with Type 2 diabetes

A new study led by researchers at Harvard T.H. Chan School of Public Health suggests that eating a low-carbohydrate diet centered on plant-based foods may significantly reduce the risk of premature death in people with Type 2 diabetes.

The findings show that certain dietary patterns were associated with a 24 percent reduction in all-cause mortality, along with lower risks of cardiovascular disease and cancer-related deaths among people living with the condition.

Published in Diabetes Care, the study is the first prospective cohort analysis to examine how low-carbohydrate dietary patterns relate to long-term mortality outcomes in individuals already diagnosed with Type 2 diabetes.

What the study found

Researchers analyzed 34 years of health data from 7,224 women in the Nurses’ Health Study and 2,877 men in the Health Professionals Follow-up Study, all of whom developed Type 2 diabetes after entering the cohorts.

Participants completed detailed questionnaires every two years, allowing researchers to track diet quality and classify carbohydrate intake based on food sources such as plant proteins, animal proteins, whole grains, and refined carbohydrates.

“While avoiding refined and highly-processed carbohydrates has been widely recommended to lower the risk of developing Type 2 diabetes, our study provides the first empirical evidence on how low-carb diets can help manage the progression of existing diabetes,” said lead author Yang Hu, research associate in the Department of Nutrition.

Not all low-carb diets showed benefits

Researchers found that not all low-carbohydrate diets were equally beneficial.

Diets high in animal-based proteins and fats, as well as those rich in refined carbohydrates such as added sugars, potatoes, and processed grains, were not significantly linked to reduced mortality risk.

In contrast, plant-based low-carbohydrate diets showed the strongest health benefits.

Stronger protection with higher-quality foods

The most favorable outcomes were seen in participants whose low-carbohydrate diets emphasized:

  • Vegetables and fruits
  • Whole grains
  • Legumes and plant-based proteins
  • Healthy fats from plant sources

These dietary patterns were associated not only with lower overall mortality but also with reduced risk of cardiovascular disease and cancer-related death.

Combined lifestyle habits amplify benefits

Researchers also observed that the strongest health benefits occurred in individuals who combined healthy eating with other positive lifestyle habits such as not smoking, exercising regularly, and drinking alcohol in moderation.

“This study, once again, underscores the importance of diet quality when choosing among various diets for diabetes control and management,” said senior author Qi Sun, associate professor in the Departments of Nutrition and Epidemiology.

Key takeaway

The findings suggest that in people with Type 2 diabetes, the quality of carbohydrates — not just the quantity — plays a critical role in long-term health outcomes, with plant-based low-carbohydrate diets offering the greatest potential benefit.

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