Type 1 diabetes is associated with low bone mineral density(BMD) and type 2 diabetes with normal or high BMD.

Cystatin C is a small molecule that is used to measure kidney function but it's not a troponin of the kidney. It has been associated with many other diseases like atrial fibrillation, depressive symptoms, melanoma, etc.

This crossectional clinical study was done to evaluate the association between Cystatin C and Bone mineral density in both types of diabetic patients.

This is a cross-sectional study of adults with diabetes to determine the association of cystatin C with bone mineral density(BMD). All the inpatient in the department of endocrinology and metabolism in the fifth affiliated hospital of Sun Yat-Sen University will be screened for 5 to 6 months. Those satisfying the inclusion and exclusion criteria will be included in the study after signing the informed consent.

The patient's blood will be withdrawn in the morning after 8 hours of fasting and sent to the laboratory of the hospital for blood lipids, Hba1c, urinary Albumin creatinine ratio, uric acid, GGT, vitamin D, calcium, cystatin C, βserum collagen type 1 cross-linked C-telopeptide(βCTX),procollagen type I N-terminal propeptide( P1NP), phosphorus, alkaline phosphatase. Smoking habits, duration of diabetes, diabetes medications, and fracture history will be asked. The history of smoking is classified as

1. Non-smokers: Subjects who have never smoked any products (cigarettes, pipes or cigars) during their lifetime;
2. Smoking cessation: a person who smokes one or more products but stops smoking at least one month prior to the baseline survey;
3. Current smokers: A subject or any other product that smokes at least one cigarette per day.

The pelvic BMD, Vertebral body BMD will be measured in the physical examination department of the hospital and divided into normal, osteopenia, osteoporosis.

All covariates will be extracted to SPSS v.23 for statistical analysis to evaluate the association of Cystatin C and BMD.

Inclusion Criteria:

• Type 1 or type 2 diabetes male / female, older than 50 years old.

Exclusion Criteria:

• Use of any drug that affects bone metabolism (bisphosphonate, denosumab, teriparatide, steroids, anticancer drugs, thyroid hormones, antidepressants, antiretrovirals, calcium, vitamins A/D)
• Any disease affecting bone minerals (hyperthyroidism, hypothyroidism, parathyroid disease, Cushing's disease, rickets/osteomalacia, collagen disorders, rheumatoid arthritis)
• Kidney disease, urinary albumin-creatinine ratio greater than 30 mg / g or GFR <60ml / min / 1.73m2.

Inpatient in the department of endocrinology and metabolism in the fifth affiliated hospital of Sun Yat-Sen University.