In Type 2 Diabetes, Low Carb Diet Linked to Lower Risk of Death from Cancer, Cardiovascular Disease

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Using data from a pair of major studies, investigators from the Harvard T.H. Chan School of Public Health shed new light on the impact of low-carbohydrate diet scores in people with type 2 diabetes.

Qi Sun, MD, MMS, ScD, of Harvard T.H. Chan School of Public Health

Qi Sun, MD, MMS, ScD

Better low-carbohydrate diet scores were linked to a lower risk of overall, cardiovascular, and cancer mortality among people with type 2 diabetes, according to the results of a new study.1

Leveraging data from the Nurses’ Health Study and the Health Professionals Follow-up Study, investigators determined greater adherence to a low-carbohydrate dietary pattern was associated with a lower risk of mortality, with this risk reduction amplified when combined with other healthy lifestyle choices.1

“Among individuals with diabetes, adopting low-carbohydrate diet patterns that emphasized high-quality sources of macronutrients was significantly associated with lower total, cardiovascular, and cancer mortality,” wrote investigators.1 “Combining healthy versions of the low-carbohydrate diet with other healthy lifestyle behaviors after diabetes diagnosis may confer additional health benefits.”

The emphasis on identifying optimal nutrition and dietary patterns for various subgroups of the population has taken on new life in recent years, including a renewed interest in the effects of low carbohydrates. In October 2022, a study from the Tulane University School of Public Health and Tropical Medicine suggested adherence to a low-carbohydrate diet in people with prediabetes and type 2 diabetes was associated with significant improvements in HbA1c, fasting plasma glucose, and body weight at 6 months compared to usual diet.2

In the current study, Qi Sun, MD, MMS, ScD, associate professor in the Departments of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, and a team of investigators sought to prospectively examine the association between post-diagnosis low-carbohydrate diet patterns and mortality among individuals. With this in mind, investigators designed their study as an analysis of data obtained from participants within the Nurses’ Health Study and Health Professionals Follow-up Study.

Using data from participants with dietary information, investigators calculated overall total low-carbohydrate diet scores (LCDS) based on the percentage of energy as total carbohydrates. For further analysis, investigates created vegetable (VLCDS), animal (ALCDS), healthy (HLCDS), and unhealthy LCDS (ULCDS) to assess the impact of carbohydrates derived from different sources and quality of macronutrients. The primary outcomes of interest for the study were all-cause, cardiovascular, and cancer mortality after type 2 diabetes diagnosis. Investigators pointed out multivariable-adjusted Cox models were used to assess the association between the LCDS and mortality.

The overall population obtained from the aforementioned studies for the current study was 10,101 individuals, with a total follow-up time of 139,407 person-years. During the follow-up period, 4595 deaths were recorded, with 1389 classified as cardiovascular disease deaths and 881 classified as cancer deaths.1

Upon analysis, results indicated the pooled hazard ratios for total mortality per 10-point increment of postdiagnosis LCDS were 0.87 (95% CI, 0.82-0.92) for TLCDS, 0.76 (95% CI, 0.71-0.82) for VLCDS, and 0.78 (0.73-0.84) for HLCDS. Results also demonstrated both VLCDS and HLCDS were also associated with significantly lower cardiovascular disease and cancer mortality. Investigators highlighted each 10-point increase of TLCDS, VLCDS, and HLCDS from prediagnosis to postdiagnosis period was associated with a 12% (95% CI, 7-17), 25% (95% CI, 19-30), and 25% (95% CI, 19-30) lower total mortality, respectively. However, investigators pointed out no significant associations were observed for ALCDS and ULCDS.1

“The inverse associations were stronger for low-carbohydrate diets that emphasized macronutrient intake from healthy plant-based foods, and these low-carbohydrate diets were also associated with significantly lower cardiovascular disease and cancer mortality,” investigators added. “In contrast, low-carbohydrate diets that emphasized animal protein or fat were not significantly associated with any study outcomes.”

References:

  1. Yang Hu, Gang Liu, Edward Yu, et al. Low-Carbohydrate Diet Scores and Mortality Among Adults With Incident Type 2 DiabetesDiabetes Care 2023; dc222310. https://doi.org/10.2337/dc22-2310
  2. Campbell P. Low-carb diet could improve untreated hba1c in people with prediabetes, type 2 diabetes. Endocrinology Network. https://www.endocrinologynetwork.com/view/low-carb-diet-could-improve-untreated-hba1c-in-people-with-prediabetes-type-2-diabetes. Published October 26, 2022. Accessed February 16, 2023.

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