This study examined the associations between overall and various subtypes of low-carbohydrate diet (LCD) on all-cause, cardiovascular and cancer-related mortality in people with type 2 diabetes. Data from two prospective cohort studies of healthcare professionals in the USA were evaluated. Participants performed a validated food frequency questionnaire every four years, starting in 1976 or 1986.
Total LCD scores were based on the percentage of total energy intake from carbohydrate, and diets were further divided into those characterised by high or low proportions of plant- or animal-based protein/fat, and those that were healthy (high-plant, low-animal, and low in starchy, sugary and refined carbohydrates) or unhealthy (vice versa). All diets were scored from 0 (highest carbohydrate intake) to 30 (lowest intake).
Data were analysed from 10 101 individuals who developed type 2 diabetes over the course of the study, with 139 407 person-years of follow-up. A total of 4595 deaths occurred, including 1389 from cardiovascular causes and 881 from cancer. After adjustment for a multitude of confounding factors, each 10-point increment of LCD score was associated with a 13% reduction in all-cause mortality. In particular, high-plant LCD scores reduced mortality by 24% and healthy LCD scores reduced it by 22%; however, high-animal and unhealthy LCDs did not have any significant benefit.
In addition, plant-based and healthy LCDs were associated with reduced cardiovascular and cancer-related mortality; however, total LCD scores and animal and unhealthy LCDs had no significant effect.
When comparing changing diets before and after type 2 diabetes diagnosis, each 10-point increase in total LCD score post-diagnosis was associated with a 12% reduction in total mortality, while increases in plant-based and healthy LCD scores both reduced mortality by 25%.
The authors conclude that greater adherence to a low-carbohydrate dietary pattern is associated with significantly lower mortality in people with type 2 diabetes, as is reducing carbohydrate intake following diabetes diagnosis. The benefits are greater for LCDs that emphasise macronutrient intake from plant-based and healthy foods, while LCDs that emphasise animal-based and unhealthy foods do not confer such benefits.
Attempts to achieve remission, or at least a substantial improvement in glycaemic control, should be the initial focus at type 2 diabetes diagnosis.
9 May 2024