Objective To explore the expression level and clinical significance of serum C1q/tumor necrosis factor related protein 3 (CTRP3) in diabetes patients complicated with osteoporosis.

Methods A total of 93 type 2 diabetes patients complicated with osteoporosis from January 2020 to December 2021 were selected as observation group, and 80 patients with simple type 2 diabetes in the same period were selected as control group. The clinical materials such as demographic data, glucose and lipid metabolism indicators, bone metabolism indicators and bone mineral density in both groups were retrospectively analyzed, and the serum CTRP3 level in both groups was detected by enzyme-linked immunosorbent assay. Multiple linear regression analysis was used to analyze the correlations of serum CTRP3 with glucose and lipid metabolism indicators, bone metabolism indicators and bone density; the Logistic regression model was used to analyze the influencing factors of osteoporosis; the receiver operating characteristic (ROC) curve was used to evaluate the value of serum CTRP3 in diagnosing type 2 diabetes patients complicated with osteoporosis.

Results In the observation group, the ratios of female patients and patients with smoking history were significantly higher than those in the control group, the age was significantly older than that in the control group, the course of diabetes was significantly longer than that in the control group, the fasting blood glucose (FBG), insulin resistance index (HOMA-IR), fasting insulin (FINS), glycated hemoglobin (HbA1c), N-terminal middle molecular fragment of osteocalcin (N-MID), β isomer of C-terminal telopeptide of type Ⅰ collagen (β-CTX) and tartrate-resistant acid phosphatase 5b (TRACP-5b) levels were significantly higher than those in the control group, while serum CTRP3 level, body mass index (BMI), bone mineral density, propeptide of type Ⅰ procollagen (PINP), carboxyterminal propeptide of type Ⅰ procollagen (PICP) and bone alkaline phosphatase (B-ALP) were significantly lower than those in the control group (P < 0.05). FBG, HOMA-IR, FINS, HbA1c, N-MID, β-CTX and TRACP-5b were negatively correlated with CTRP3 level (P < 0.05), while PINP, PIC and B-ALP were positively correlated with CTRP3 level (P < 0.05). Logistic regression analysis model showed that FBG, HOMA-IR, FINS, HbA1c, CTRP and bone density as well as bone metabolism indicators were the independent influencing factors of type 2 diabetes patients complicated with osteoporosis (P < 0.05), of which FBG, HOMA-IR, FINS, HbA1c, N-MID, β-CTX and TRACP-5b were risk factors (OR>1, P < 0.05), and CTRP3, bone density, PINP, PICP and B-ALP were protective factors (OR < 1, P < 0.05). The area under the curve (AUC) of CTRP3 in diagnosing osteoporosis was 0.815, and the sensitivity and specificity were 84.95% and 63.75% respectively; the AUC of CTRP3 combined with BMD in diagnosing osteoporosis was 0.882, and the sensitivity and specificity were 83.87% and 78.75% respectively.

Conclusion Serum CTRP3 is downregulated in diabetes patients with osteoporosis, and is closely related to glucose metabolism disorder, bone metabolism abnormality and bone density reduction, which can affect the occurrence of osteoporosis in diabetes patients.