Low-fat vegan diet tied to improved insulin sensitivity for adults with type 1 diabetes
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Key takeaways:
- A low-fat vegan diet for 12 weeks reduced total daily insulin needs for adults with type 1 diabetes.
- A low-fat vegan diet was linked to greater drops in total and HDL cholesterol than a portion-controlled diet.
Eating a low-fat vegan diet induced a greater improvement in insulin sensitivity and a larger reduction in total daily insulin dose than a portion-controlled diet for adults with type 1 diabetes, according to study findings.
“With type 1 diabetes rates projected to possibly increase more than 100% in the next 15 years and the cost of insulin remaining stubbornly high, physicians should counsel patients with type 1 diabetes to try a low-fat vegan diet to not only help reduce their insulin requirements, but to reduce their heart disease risk and improve their overall health,” Hana Kahleova, MD, PhD, director of clinical research for the Physicians Committee for Responsible Medicine, told Healio.
Kahleova and colleagues conducted a single-center randomized clinical trial that enrolled 58 adults aged 18 years and older with type 1 diabetes and a stable insulin regimen for at least 3 months. Participants were randomly assigned, 1:1, to eat a low-fat vegan diet consisting of vegetables, grains, legumes and fruits or a portion-controlled diet with individualized eating plans that reduced daily energy intake by 500 kcal to 1,000 kcal per day while keeping carbohydrate intake stable. All adults received weekly online nutrition education classes and support from registered dietitians. Total daily insulin dose, insulin sensitivity as measured by carbohydrate-to-insulin ratio, body weight and HbA1c were collected at baseline and 12 weeks. A staff member collected dietary intake data. Physical activity was self-reported. All participants wore a continuous glucose monitor during the study.
The findings were published in Clinical Diabetes.
There were 35 adults who completed the study, including 18 in the low-fat vegan diet group and 17 in the portion-controlled diet group. Adults eating a vegan diet had a greater reduction in body weight (mean difference, –4.3 kg; 95% CI, –6.1 to –2.4; P < .001) and BMI (mean difference, –1.6 kg/m2; 95% CI, –2.2 to –0.9; P < .001) than the portion-control group.
A greater decline in total daily insulin dose was observed with a vegan diet compared with a portion-controlled diet (mean difference, –10.7 U; 95% CI, –21.3 to –0.2; P = .046). Adults in the vegan diet group had a greater increase in insulin sensitivity than the portion-control diet group (mean difference, 8.2 g of carbohydrate per unit of insulin; 95% CI, 3.6-12.8; P = .001). There were no differences for change in HbA1c or CGM metrics between the two groups.
Changes in total daily insulin dose and insulin sensitivity correlated with changes in body weight. Each 1 kg of body weight loss was associated with a 2.16 U decrease in daily insulin dose and a 0.9 U increase in insulin sensitivity. Changes in insulin sensitivity correlated with changes in carbohydrate and fiber intake. Each 10 g increase in carbohydrate intake was associated with a 0.42 g increase in carbohydrate per unit of insulin. Each 10 g increase in fiber intake was associated with an increase of 4.29 g of carbohydrate per unit of insulin.
“We knew from our previous research studies that a low-fat vegan diet improved insulin sensitivity, lowered weight and improved cardiovascular health in people with type 2 diabetes, so we were hopeful that we would see similar improvements in patients with type 1 diabetes,” Kahleova said. “We were pleased to see how dramatically a low-fat vegan diet improved insulin sensitivity and reduced insulin needs in people with type 1 diabetes.”
Adults eating a vegan diet had greater declines in total cholesterol (mean difference, –21.4 mg/dL; 95% CI, –35.6 to –7.2; P = .004) and HDL cholesterol (mean difference, –9 mg/dL; 95% CI, –14.5 to –3.4; P = .003). No differences in LDL cholesterol or triglycerides were observed between the two groups.
Kahleova said the findings need to be replicated in a larger study.
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