In patients with type 2 diabetes, all dietary pattern changes are shown to outperform usual diet in improving body weight and hemoglobin A1c (HbA1c) after 6 months, and also show clinically relevant reductions in cardiovascular (CV) risk, according to the results of a systematic review and meta-analysis published in the journal Diabetes Research and Clinical Practice.
Researchers sought to identify the most effective dietary pattern for improvement in CV risk factors in individuals with type 2 diabetes. They conducted a systematic literature search for randomized controlled trials (RCTs) that compared the effects of dietary patterns on body weight, HbA1c, blood pressure, and lipid levels after 6 months and 12 months. They used 6-month changes in systolic blood pressure, HbA1c, and low-density lipoprotein cholesterol to estimate relative risk reductions for CV events.
A total of 73 RCTs on 8 different dietary patterns were included in the meta-analysis.
All dietary patterns were associated with reductions in body weight and HBA1c after
6 months, with the greatest effects reported with the low-carbohydrate diet (body weight, -4.8 kg; 95% credibility interval [CrI], -6.5 kg to -3.2 kg vs usual diet) and the Mediterranean diet (HbA1c, -1.0%; 95% CrI, -15% to -0.4% vs usual diet).
No significant 6-month blood pressure or lipid effects were observed. Further, all dietary patterns were not linked to any statistically significant effects at 12 months. The Mediterranean diet was associated with the largest expected relative risk reduction for CV events, with -15.8% (95% CI, -31.3% to 3.2%) vs usual diet.
Several limitations of the analysis include the available RCTs being low to moderate quality, even though sensitivity analyses showed that the results were not influenced by studies at high risk for bias. Further, a considerable proportion of the studies included in the meta-analysis did not disclose funding information, which might have impacted the selection of reported outcomes.
“There is a need to quantify the effects of dietary pattern interventions on the occurrence of cardiovascular events in a long-term randomized controlled trial,” the study authors wrote. “In the meantime, patients with T2DM [type 2 diabetes mellitus] should be advised to adopt a healthy diet, without a preference for any dietary pattern in particular.”
Bonekamp NE, van Damme I, Geleijnse JM, et al. Effect of dietary patterns on cardiovascular risk factors in people with type 2 diabetes. a systematic review and network meta-analysis. Diabetes Res Clin Pract. Published online December 10, 2022. doi:10.1016/j.diabres.2022.110207