This study is an observational study. Collect cotton swabs of the surface skin are obtained from the non-diabetic and diabetic patients hospitalized in the Nanfang Hospital of Southern Medical University. The investigators use omics technology to identify the structure and functions of cutaneous microbiome, analyze the characteristics of the skin flora of diabetic patients, and find the difference in skin microbiota among diabetic patients with different risk levels for developing into diabetic foot. Then, the participants will be followed up to compare the incidence of ulcers among different groups. And the skin tissues discarded during surgical operations of non-diabetic and diabetes patients are collected for pathological examination. Finally, based on the results of 16S high-throughput sequencing, metagenomics, etc., specific flora could be extracted from human skin flora cotton swabs, and animal experiments are performed to explore the effect of skin micro-ecology on diabetic skin lesions. The investigators will explore in animal experiments to regulate the influence of skin micro-ecology on diabetic skin lesions through treatment methods such as different hypoglycemic drugs and probiotic emulsions.

The study intends to explore the mechanism of diabetic skin micro-ecology in diabetic skin diseases, and find new ways of early screening and prevention for diabetic foot.

This study is a prospective observational study. Adult participants were divided into the following 5 groups (n=200, 40 in each group): control group, very low-risk group, low-risk group, moderate-risk group, and high-risk group. Sterile rayon tipped swabs were pre-moistened with a sterile solution containing 0.15 M NaCl and 0.1% Tween 20. All swabs samples were collected from the intact skin at plantar anterior. And the skin cotton swab was subjected to 16s rDNA high-throughput sequencing, metagenomic sequencing methods, etc. Based on the result, the investigators will analyse the change of the cutaneous microbiome in DM as the disease condition progresses.

The skin tissues of the control group and observation group who met the inclusion criteria were also collected during surgical operations, and pathological and immunohistochemistry tests were performed respectively to analyze the pathological changes of diabetic skin tissues in different disease progressions.

According to the results of multi-omics analysis, the research team screen for the specific flora. Then sort out and culture specific strains, and establish mouse model of microbiota transplantation in order to explore the effects of regulating skin microecology on diabetic skin lesions through different treatment methods such as hypoglycemic drugs and probiotic emulsions.

Researchers will conduct telephone follow-ups of diabetic patients, collect data, and statistically analyze the impact of changes in the skin microecology of diabetic patients on the occurrence of diabetic foot ulcers.

Inclusion Criteria:

1. Surface skin cotton swab collection

(1) Observation group: In the endocrinology department of Nanfang hospital, the patient were diagnosed with type 2 diabetes to the WHO 1999 diagnostic criteria for diabetes.

(2) Control group:

1. Control subjects that was ruled out diabetes according to the WHO 1999 diagnostic criteria for euglycemia.
2. Age ≥18 years, the patient and (or) his family members know and agree to participate in this study.

2. Skin tissue collection

(1) Observation group:

1. The patient was diagnosed with type 2 diabetes in the Endocrinology Department, Burns Department, Traumatology Orthopedics, Plastic Surgery in Nanfang hospital.
2. Patients who need surgical operations such as debridement and amputation below the knee joint due to various reasons such as diabetic foot osteomyelitis, fractures, car accidents and so on.

(2) Control group:

1. The patient without type 2 diabetes in the Endocrinology Department, Burns Department, Traumatology Orthopedics, Plastic Surgery in Nanfang hospital.
2. Patients who need surgical operations such as debridement and amputation below the knee joint due to various reasons such as post-traumatic foot osteomyelitis, fractures, car accidents and so on.
3. Age ≥18 years, the patient and (or) his family members know and agree to participate in this study.

Exclusion Criteria:

The patients Including other skin diseases, using medically prescribed soap for bathing, using cosmetics on the feet, suffering from severe liver and kidney disease, immune system disease, HIV infection, malignant tumors, or using immunosuppressive drugs within the first four weeks. The patient or (and) their family members refused to participate in this study.

The researchers judged that they are not suitable to participate in this research.

200 cases, 40 cases in each group