Diet in the management of type 2 diabetes: umbrella review of systematic reviews with meta-analyses of randomised controlled trials

Abstract

ObjectiveTo systematically summarise and evaluate the existing evidence on the effect of diet on the management of type 2 diabetes and prevention of complications.DesignUmbrella review of systematic reviews with meta-analyses of randomised controlled trials.Data sourcesPubMed, Embase, Epistemonikos, and Cochrane, from inception up to 5 June 2022.Eligibility criteria for selecting studiesSystematic reviews with meta-analyses of randomised controlled trials reporting summary effect estimates on the effect of diet on any health outcome in populations with type 2 diabetes were included in the review. Only meta-analyses with randomised controlled trials with the duration of at least 12 weeks were eligible for inclusion. Summary data were extracted by two investigators independently. Summary effect estimates with 95% confidence intervals were recalculated with a random effects model if the information provided was insufficient. Methodological quality was assessed with the A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 tool and the certainty of evidence with the Grading of Recommendations Assessment, Development, and Evaluations (GRADE) approach.Results88 publications with 312 meta-analyses of randomised controlled trials were included. Methodological quality was high to moderate in 23% and low to very low in 77% of the included publications. A high certainty of evidence was found for the beneficial effects of liquid meal replacement on reducing body weight (mean difference −2.37 kg, 95% confidence interval −3.30 to −1.44; n=9 randomised controlled trials included in the meta-analysis) and body mass index (−0.87, −1.32 to −0.43; n=8 randomised controlled trials), and of a low carbohydrate diet (<26% of total energy) on levels of haemoglobin A1c(−0.47%, −0.60% to −0.34%; n=17 randomised controlled trials) and triglycerides (−0.30 mmol/L, −0.43 to −0.17; n=19 randomised controlled trials). A moderate certainty of evidence was found for the beneficial effects of liquid meal replacement, plant based, Mediterranean, high protein, low glycaemic index, and low carbohydrate diets (<26% total energy) on various cardiometabolic measures. The remaining results had low to very low certainty of evidence.ConclusionsThe evidence indicated that diet has a multifaceted role in the management of type 2 diabetes. An energy restricted diet can reduce body weight and improve cardiometabolic health. Beyond energy restriction, dietary approaches such as plant based, Mediterranean, low carbohydrate (<26% total energy), or high protein diets, and a higher intake of omega 3 fatty acids can be beneficial for cardiometabolic health in individuals with type 2 diabetes.Systematic review registrationPROSPERO CRD42021252309.

Role of fermented dairy products in the health benefits of a mediterranean diet

“…Large body of evidence indicates that a MedDiet offers many benefits to patients with type 2 diabetes (T2D), both in the prevention of the disease and in its management such as in glycemic control [ 35 – 37 ]. This statement is based on epidemiological studies and on the results of a randomized controlled trial.…”

Nutrition and exercise: Cornerstones of health with emphasis on obesity and type 2 diabetes management—A narrative review

“…These complex interactions are crucial for regulating gene transcription, modulating the structure and function of cellular membranes, influencing ion channel activities and electrophysiological processes, and affecting a myriad of biological pathways, as elucidated by Wu et al 44 The growing body of scientific literature emphasizes the critical role of diet quality as a fundamental determinant shaping the longterm impacts of dietary practices on the incidence and management of obesity and T2D. [45][46][47] Within the scope of obesity, a robust scientific consensus exists on the benefits of consuming a diet abundant in minimally processed, bioactive foods. This dietary pattern encompasses diverse fruits, non-starchy vegetables, whole grains, nuts, seeds, legumes, oils extracted from plants, yogurt, and fish-all noted for their nutrient density and health-promoting properties.…”

“…Contemporary management of obesity and T2D now incorporates dietary pattern-based interventions. Systematic reviews have provided evidence supporting the efficacy of dietary patterns such as the Mediterranean diet, 47,55 the Dietary Approaches to Stop Hypertension (DASH) diet, 56 low-carbohydrate diets, 57 the ketogenic diet, 58 and plant-based diets 59 in reducing the prevalence of obesity and T2D. These diets emphasize the consumption of fruits, vegetables, whole grains, lean proteins, and healthy fats, while minimizing processed foods and added sugars.…”

Comparative Evaluation of a Low-Carbohydrate Diet and a Mediterranean Diet in Overweight/Obese Patients with Type 2 Diabetes Mellitus: A 16-Week Intervention Study

“…There is growing evidence leading to recommendations from numerous scientific medical societies of diabetology on the use of these dietary approaches to intervene against type 2 diabetes [ 16 , 17 , 18 ] and overall protection against cardiovascular diseases [ 19 ]. However, contemporary literature reviews assessing the comparative effects of carbohydrate restricted diets versus low-fat control diets in overweight/obese patients with type 2 diabetes mellitus have shown divergent and inconclusive results regarding the impact on glycated hemoglobin, weight loss, and cardiovascular risk factors [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Dietary fats, particularly saturated fatty acids (SFAs), have been implicated as the cause of the significant rise in obesity and its related diseases [ 24 ].…”

“…However, contemporary literature reviews assessing the comparative effects of carbohydrate restricted diets versus low-fat control diets in overweight/obese patients with type 2 diabetes mellitus have shown divergent and inconclusive results regarding the impact on glycated hemoglobin, weight loss, and cardiovascular risk factors [ 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. Dietary fats, particularly saturated fatty acids (SFAs), have been implicated as the cause of the significant rise in obesity and its related diseases [ 24 ]. On the contrary, several systematic reviews challenge the link between total SFA intake with cardiovascular disease and recent studies showed that short-chain saturated fatty acids (SCSFAs) especially from dairy foods [ 27 , 28 , 29 , 30 ] may exert potential beneficial effects both on metabolic and mental health outcomes [ 31 , 32 , 33 ].…”