The ageing of our country is increasing and the ageing of the population has led to a significant increase in aging related diseases. During the aging process of the organism, cellular senescence can occur in all systems of the body, of which the senescence of the immune system is called immunosenescence. Some studies have shown that metabolic disorders can also trigger aging. This study investigated the effect of nicotinamide mononucleotide (NMN) supplementation on immunosenescence in middle-aged and elderly people through a placebo-controlled long-range clinical trail, aiming to provide a new method to improve immunosenescence. The effects of NMN supplementation on glucose and lipid metabolic indexes, body composition and telomere length of peripheral blood cells are also investigated, which may open up new ideas for the prevention and treatment of glucose and lipid metabolic diseases.

A randomised, placebo-controlled, parallel group study to assess the efficacy and safety of NMN in middle-aged and elderly people with immunosenescence. People aged 50-70 years will be included in the study. Participants will be given NMN SR tablets (1000mg/tablet) or placebo, 1 tablet daily before breakfast. The study treatment period lasts 26 weeks. Investigator visits will be conducted at months 1, 3 and 6. Percentage of CD3+CD8+CD27-CD28- cells to total CD3+CD8+ T cells will be used as the primary evaluation metrics for assessing efficacy.Liver fat content, body composition analysis, pancreatic β-cell function, telomere length, fasting blood glucose, glycosylated hemoglobin, and cardiorespiratory fitness will be used as secondary indicators for efficacy assessment. Physiological and biochemical parameters such as blood and urine routine, liver and kidney function will be used for safety assessment.

Inclusion Criteria:

1. Age 50-70 years with overweight or obesity (BMI 24kg/m2);
2. At least one of the following three: metabolism-related fatty liver disease (diagnosed by ultrasound); pre-diabetes; type 2 diabetes mellitus with HbA1c <7% without glucose-lowering drug therapy;
3. Agreed to participate in the trial and could adhere to the follow-up and visit the hospital on their own; signed the informed consent form.

Exclusion Criteria:

1. Patients with tumours;
2. Patients with autoimmune diseases (excluding Hashimoto's thyroiditis);
3. Severe cardiovascular disease or cardiac insufficiency;
4. Systolic blood pressure > 160 mmHg or diastolic blood pressure > 100 mmHg;
5. Chronic obstructive pulmonary disease;
6. Chronic active hepatitis or cirrhosis;
7. Chronic renal insufficiency;
8. Stroke patients
9. Severe haematological diseases;
10. Infectious diseases;
11. Mental illness;
12. Other conditions that, in the opinion of the investigator, may affect the results of the study;
13. Those who have used NMN or other anti-aging agents within six months.
14. Premenopausal woman
15. ALT, AST values are more than three times higher than the upper limit of the normal reference range