Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial.

Clinical nutrition (Edinburgh, Scotland). 2021;40(5):2587-2598

Plain language summary

Older people have a higher risk of developing Type 2 diabetes (T2D) due to the possibility of β-cell dysfunction due to ageing. Sardines are believed to be protective against the development of T2D. Therefore, this randomised controlled trial evaluated the preventative effects of a sardine-rich diet in elderly prediabetic patients. For one year, both the sardine group (SG) and control group (CG) followed a T2D prevention diet, with the SG consuming 200 g of sardines each week. Both groups improved body weight, BMI, waist and hip circumference, and body composition. Taurine, EPA, DHA, omega-3 fatty acid, calcium, iodine, zinc, phosphorous and fluoride, vitamin B12 and D, and lycopene and tocopherols were found to be higher in the SG than the CG, indicating the sardines were protective against T2D. In SG, HDL cholesterol and adiponectin levels were significantly increased, and blood pressure and triglycerides were decreased, signalling a reduced risk of T2D and cardiovascular disease. In addition, SG showed a reduction in HOMA-IR and an Omega-3 fatty acid was substituted for Omega-6 fatty acids in the erythrocyte membrane, suggesting a reduced risk of T2D. Further robust research is required to confirm the protective effect of a sardine-enriched diet against T2D. It may be useful to healthcare providers to comprehend how a sardine-enriched diet could improve obesity, T2D and CVD markers in pre-diabetic elderly patients.


BACKGROUND Fish could play a role in preventing type 2 diabetes (T2D) but there has been little specification about the type of fish and the preventive mechanism involved in its health claim. The sardine is a source of omega-3 and taurine that, in isolation or in synergy, would produce T2D-delaying through different molecular mechanism. HYPOTHESIS The consumption of twice a week of sardine, during one year would reduce T2D-developing risk in a population with prediabetes (preDM) and old age. DESIGN 152 subjects with fasting glucose between 100-124 mg/dL aged ≥65 yo were recruited from three primary care centers in Barcelona and were randomly distributed among two interventional groups: control group (CG) and sardine group (SG). Both groups received same T2D-prevention nutritional during a year but only SG had to add 200 g of sardine per week. All variables were collected before to start and at the end of the diet. (ClinicalTrials.gov: NCT03557541). RESULTS 152 people were randomized into CG (n=77) and SG (n=75) with 18 and 12 drop outs respectively. Subjects in SG, significantly compared to CG, decreased percentage classified-individuals in a very high risk group to develop T2D according to FINDRISC (p=0.035). In addition to increasing HDL-cholesterol and adiponectin and decreasing triglycerides (p<0.05) and blood pressure (<0.05), SG showed a lower HOMA-IR (p=0.032). The consumption of sardine characteristics nutrients as omega-3, EPA and DHA, vitamin D, fluorine and taurine were higher for SG (p<0.05). These results agreed with the increased of taurine, fatty acid (FA) omega-3 and bile acids circulating metabolites (p<0.05). Changes erythrocyte membrane FA were detected only in SG with a decrease of 5 omega-6 FA (p<0.001) and an increase of 3 omega-3 FA types (p<0.001). CONCLUSION We conclude that a year T2D-prevention diet with sardine supplementation has a greater protective effect against developing T2D and CV events.

Lifestyle medicine

Fundamental Clinical Imbalances : Hormonal ; Immune and inflammation
Patient Centred Factors : Mediators/Sardine-enriched diet
Environmental Inputs : Diet ; Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood
Bioactive Substances : Sardine-enriched diet

Methodological quality

Jadad score : 3
Allocation concealment : No