Sardines and type 2 diabetes risk in older people with prediabetes
What it found
Eating 200 g of sardines a week for a year lowered blood pressure, improved cholesterol and reduced diabetes risk scores in older people with prediabetes.
Both groups also received the same general diet advice.
What they found
Studies in people
Diabetes risk scores
Fewer people in the sardine group stayed in the very high risk category for type 2 diabetes. About 29.6% of them moved out of that top risk group, compared with only 4.9% in the control group.
Blood pressure
Only the sardine group saw drops in both systolic and diastolic blood pressure over the year. The control group did not show these changes.
Cholesterol and triglycerides
The sardine group had a rise in HDL cholesterol and a fall in triglycerides. They also showed less insulin resistance than the control group.
New diabetes cases
Four people in the control group and two in the sardine group developed type 2 diabetes during the year. The authors say this difference was too small to be certain it was caused by the sardines.
Omega-3 levels in blood
The sardine group had higher omega-3 fats in their red blood cell membranes and a higher omega-3 index at the end of the year. The control group did not show these increases.
What the authors conclude
- They conclude that adding sardines to a standard diabetes prevention diet for a year offers extra protection against developing type 2 diabetes and heart problems in older people with prediabetes.
- Their results suggest the benefits come from improvements in blood chemistry, blood pressure and fat composition in cell membranes.
How it was done
Older age raises the chance of developing type 2 diabetes. The authors wanted to see if adding sardines, which are rich in omega-3 fats and taurine, could help prevent this without requiring weight loss diets that might harm older adults.
The researchers recruited 152 people aged 65 or older with prediabetes from clinics in Barcelona. Everyone got the same diet advice for one year, but half were randomly chosen to also eat 200 g of canned sardines each week. Measurements were taken before and after the year.
What it can’t tell you
- The study used canned sardines in olive oil, so scientists do not yet know if fresh sardines would give the same results.
- Only 122 of the original 152 people finished the trial, so dropouts may have affected the final numbers.
- The study lasted one year, so it cannot show whether these effects last longer.
Who paid
- Authors work at
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) - Hospital Clinic of Barcelona, Spain; Universitat Oberta de Catalunya, Spain; Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Spain
The paper
- Title
- Type 2 diabetes preventive effects with a 12-months sardine-enriched diet in elderly population with prediabetes: An interventional, randomized and controlled trial
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Díaz-Rizzolo DA, Serra A, Colungo C, Sala-Vila A, Sisó-Almirall A, Gomis R (2021). 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). doi:10.1016/j.clnu.2021.03.014Free full textPubMed 33932804DOI
Summary written 1 Oct 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error