Bone-Derived Factors: A New Gateway to Regulate Glycemia

Osteogenic effect of alogliptin in chemical-induced bone loss: a tri-modal in silico, in vitro, and in vivo analysis

OBJECTIVE

To investigate the effects of Alogliptin in chemical-induced post-menopausal osteoporosis.

METHODOLOGY

The binding affinity of alogliptin with osteogenic proteins was analysed in silico. The effect of alogliptin on osteogenic proteins and mineralization of osteoblastic cells was evaluated in UMR-106 cells. Further, in vivo anti-osteoporotic activity of alogliptin was evaluated in postmenopausal osteoporosis. Various bone turnover markers were assayed in serum. This followed the analysis of microarchitecture of bone, histology, and immunohistochemistry (IHC) of bone tissue.

RESULTS

Docking scores showed that alogliptin has binding affinity for bone alkaline phosphatase (BALP), osteocalcin, and bone morphogenic protein (BMP-2). Alogliptin also enhanced mineralization of osteoblast cells, evidenced with increased ALP, osteocalcin, and BMP-2. Animal studies revealed significant elevation of bone formation markers, bone ALP, osteocalcin and BMP-2, and decreased bone resorption markers, receptor activator of NF-κβ (RANKL), cathepsin K (CTSK), tartrate resistant acid phosphatase (TRAcP5b) in VCD-induced post-menopausal osteoporosis. Micro computed tomography (μCT) analysis and histology of femur bone and lumbar vertebrae demonstrated decrease in trabecular separation and improved bone density. IHC of femur showed reduced DPP4 enzyme.

CONCLUSIONS

Alogliptin increased mineralization in osteoblast cells. It had beneficial effects also altered bone turnover markers, repaired the trabecular microstructure, improved bone mineral density, and exhibited bone forming capacity targeting DPP-4 enzyme in postmenopausal osteoporosis.

Bone-derived factors mediate crosstalk between skeletal and extra-skeletal organs

Bone has long been acknowledged as a fundamental structural entity that provides support and protection to the body's organs. However, emerging research indicates that bone plays a crucial role in the regulation of systemic metabolism. This is achieved through the secretion of a variety of hormones, cytokines, metal ions, extracellular vesicles, and other proteins/peptides, collectively referred to as bone-derived factors (BDFs). BDFs act as a medium through which bones can exert targeted regulatory functions upon various organs, thereby underscoring the profound and concrete implications of bone in human physiology. Nevertheless, there remains a pressing need for further investigations to elucidate the underlying mechanisms that inform the effects of bone on other body systems. This review aims to summarize the current findings related to the roles of these significant modulators across different organs and metabolic contexts by regulating critical genes and signaling pathways in vivo. It also addresses their involvement in the pathogenesis of various diseases affecting the musculoskeletal system, circulatory system, glucose and lipid metabolism, central nervous system, urinary system, and reproductive system. The insights gained from this review may contribute to the development of innovative therapeutic strategies through a focused approach to bone secretomes. Continued research into BDFs is expected to enhance our understanding of bone as a multifunctional organ with diverse regulatory roles in human health.

Prediction model for low bone mass mineral density in type 2 diabetes: an observational cross-sectional study

PURPOSE

Considering the prevalence of type 2 diabetes (T2D), osteoporosis should be considered a serious complication. However, an effective tool for the assessment of low bone mass mineral density (BMD) in T2D patients is not currently available. Therefore, the aim of our study was to establish a simple-to-use risk assessment tool by exploring risk factors for low BMD in T2D patients.

METHODS

This study included 436 patients with a low BMD and 381 patients with a normal BMD. Multiple logistic regression analysis was performed to evaluate risk factors for low BMD in T2D patients. A nomogram was then developed from these results. A receiver operating characteristic (ROC) curve, calibration plot, and goodness-of-fit test were used to validate the nomogram. The clinical utility of the nomogram was also assessed.

RESULTS

Multivariate logistic regression indicated that age, sex, education, body mass index (BMI), fasting C-peptide, high-density cholesterol (HDL), alkaline phosphatase (ALP), estimated glomerular filtration rate (eGFR), and type I collagen carboxy terminal peptide (S-CTX) were independent predictors for low BMD in T2D patients. The nomogram was developed from these variables using both the unadjusted area under the curve (AUC) and the bootstrap-corrected AUC (0.828). Calibration plots and the goodness-of-fit test demonstrated that the nomogram was well calibrated.

CONCLUSIONS

The nomogram-illustrated model can be used by clinicians to easily predict the risk of low BMD in T2D patients. Our study also revealed that common factors are independent predictors of low BMD risk. Our results provide a new strategy for the prediction, investigation, and facilitation of low BMD in T2D patients.

The pan-liver network theory: From traditional chinese medicine to western medicine

In traditional Chinese medicine (TCM), the liver is the "general organ" that is responsible for governing/maintaining the free flow of qi over the entire body and storing blood. According to the classic five elements theory, zang-xiang theory, yin-yang theory, meridians and collaterals theory, and the five-viscera correlation theory, the liver has essential relationships with many extrahepatic organs or tissues, such as the mother-child relationships between the liver and the heart, and the yin-yang and exterior-interior relationships between the liver and the gallbladder. The influences of the liver to the extrahepatic organs or tissues have been well-established when treating the extrahepatic diseases from the perspective of modulating the liver by using the ancient classic prescriptions of TCM and the acupuncture and moxibustion. In modern medicine, as the largest solid organ in the human body, the liver has the typical functions of filtration and storage of blood; metabolism of carbohydrates, fats, proteins, hormones, and foreign chemicals; formation of bile; storage of vitamins and iron; and formation of coagulation factors. The liver also has essential endocrine function, and acts as an immunological organ due to containing the resident immune cells. In the perspective of modern human anatomy, physiology, and pathophysiology, the liver has the organ interactions with the extrahepatic organs or tissues, for example, the gut, pancreas, adipose, skeletal muscle, heart, lung, kidney, brain, spleen, eyes, skin, bone, and sexual organs, through the circulation (including hemodynamics, redox signals, hepatokines, metabolites, and the translocation of microbiota or its products, such as endotoxins), the neural signals, or other forms of pathogenic factors, under normal or diseases status. The organ interactions centered on the liver not only influence the homeostasis of these indicated organs or tissues, but also contribute to the pathogenesis of cardiometabolic diseases (including obesity, type 2 diabetes mellitus, metabolic [dysfunction]-associated fatty liver diseases, and cardio-cerebrovascular diseases), pulmonary diseases, hyperuricemia and gout, chronic kidney disease, and male and female sexual dysfunction. Therefore, based on TCM and modern medicine, the liver has the bidirectional interaction with the extrahepatic organ or tissue, and this established bidirectional interaction system may further interact with another one or more extrahepatic organs/tissues, thus depicting a complex "pan-hepatic network" model. The pan-hepatic network acts as one of the essential mechanisms of homeostasis and the pathogenesis of diseases.

Bone mineralisation and glucose metabolism

Recent advancements in the bone biology field have identified a novel bone-metabolism axis. In this review, we highlight several novel studies that further our knowledge of new endocrine functions of bone; explore remaining unanswered questions; and discuss translational challenges in this complex era of bone biology research.

Systemic effects of abnormal bone resorption on muscle, metabolism, and cognition

Skeletal tissue is dynamic, undergoing constant remodeling to maintain musculoskeletal integrity and balance in the human body. Recent evidence shows that apart from maintaining homeostasis in the local microenvironment, the skeleton systemically affects other tissues. Several cancer-associated and noncancer-associated bone disorders can disrupt the physiological homeostasis locally in the bone microenvironment and indirectly contribute to dysregulation of systemic body function. The systemic effects of bone on the regulation of distant organ function have not been widely explored. Recent evidence suggests that bone can interact with skeletal muscle, pancreas, and brain by releasing factors from mineralized bone matrix. Currently available bone-targeting therapies such as bisphosphonates and denosumab inhibit bone resorption, decrease morbidity associated with bone destruction, and improve survival. Bisphosphonates have been a standard treatment for bone metastases, osteoporosis, and cancer treatment-induced bone diseases. The extraskeletal effects of bisphosphonates on inhibition of tumor growth are known. However, our knowledge of the effects of bisphosphonates on muscle weakness, hyperglycemia, and cognitive defects is currently evolving. To be able to identify the molecular link between bone and distant organs during abnormal bone resorption and then treat these abnormalities and prevent their systemic effects could improve survival benefits. The current review highlights the link between bone resorption and its systemic effects on muscle, pancreas, and brain.

Regulatory Roles of Bone in Neurodegenerative Diseases

Osteoporosis and neurodegenerative diseases are two kinds of common disorders of the elderly, which often co-occur. Previous studies have shown the skeletal and central nervous systems are closely related to pathophysiology. As the main structural scaffold of the body, the bone is also a reservoir for stem cells, a primary lymphoid organ, and an important endocrine organ. It can interact with the brain through various bone-derived cells, mostly the mesenchymal and hematopoietic stem cells (HSCs). The bone marrow is also a place for generating immune cells, which could greatly influence brain functions. Finally, the proteins secreted by bones (osteokines) also play important roles in the growth and function of the brain. This article reviews the latest research studying the impact of bone-derived cells, bone-controlled immune system, and bone-secreted proteins on the brain, and evaluates how these factors are implicated in the progress of neurodegenerative diseases and their potential use in the diagnosis and treatment of these diseases.

Individuals with type 2 diabetes mellitus show dimorphic and heterogeneous patterns of loss in femoral bone quality

Type 2 diabetes mellitus (T2DM), a metabolic disease on the rise, is associated with substantial increase in bone fracture risk. Because individuals with T2DM have normal or high bone mineral density (BMD), osteodensitometric measurements of BMD do not predict fracture risk with T2DM. Here, we aim to identify the underlying mechanism of the diabetes-induced fracture risk using a high-resolution multi-scale analysis of human cortical bone with special emphasis on osseous cellular activity. Specifically, we show increased cortical porosity in a subgroup of T2DM individuals accompanied by changed mineralization patterns and glycoxidative damage to bone protein, caused by non-enzymatic glycation of bone by reducing sugar. Furthermore, the high porosity T2DM subgroup presents with higher regional mineralization heterogeneity and lower mineral maturity, whereas in the T2DM subgroup regional higher mineral-to-matrix ratio was observed. Both T2DM groups show significantly higher carboxymethyl-lysine accumulation. Our results show a dimorphic pattern of cortical bone reorganization in individuals afflicted with T2DM and hence provide new insight into the diabetic bone disease leading to increased fracture risk.

Effects of fasting on the expression pattern of FGFs in different skeletal muscle fibre types and sexes in mice

Fibroblast growth factors (FGFs) belong to a large family comprising 22 FGF polypeptides that are widely expressed in tissues. Most of the FGFs can be secreted and involved in the regulation of skeletal muscle function and structure. However, the role of fasting on FGF expression pattern in skeletal muscles remains unknown. In this study, we combined bioinformatics analysis and in vivo studies to explore the effect of 24-h fasting on the expression of Fgfs in slow-twitch soleus and fast-twitch tibialis anterior (TA) muscle from male and female C57BL/6 mice. We found that fasting significantly affected the expression of many Fgfs in mouse skeletal muscle. Furthermore, skeletal muscle fibre type and sex also influenced Fgf expression and response to fasting. We observed that in both male and female mice fasting reduced Fgf6 and Fgf11 in the TA muscle rather than the soleus. Moreover, fasting reduced Fgf8 expression in the soleus and TA muscles in female mice rather than in male mice. Fasting also increased Fgf21 expression in female soleus muscle and female and male plasma. Fasting reduced Fgf2 and Fgf18 expression levels without fibre-type and sex-dependent effects in mice. We further found that fasting decreased the expression of an FGF activation marker gene-Flrt2 in the TA muscle but not in the soleus muscle in both male and female mice. This study revealed the expression profile of Fgfs in different skeletal muscle fibre types and different sexes and provides clues to the interaction between the skeletal muscle and other organs, which deserves future investigations.

The Interplay Between Bone and Glucose Metabolism

The multiple endocrine functions of bone other than those related to mineral metabolism, such as regulation of insulin sensitivity, glucose homeostasis, and energy metabolism, have recently been discovered. In vitro and murine studies investigated the impact of several molecules derived from osteoblasts and osteocytes on glucose metabolism. In addition, the effect of glucose on bone cells suggested a mutual cross-talk between bone and glucose homeostasis. In humans, these mechanisms are the pivotal determinant of the skeletal fragility associated with both type 1 and type 2 diabetes. Metabolic abnormalities associated with diabetes, such as increase in adipose tissue, reduction of lean mass, effects of hyperglycemia per se, production of the advanced glycation end products, diabetes-associated chronic kidney disease, and perturbation of the calcium-PTH-vitamin D metabolism, are the main mechanisms involved. Finally, there have been multiple reports of antidiabetic drugs affecting the skeleton, with differences among basic and clinical research data, as well as of anti-osteoporosis medication influencing glucose metabolism. This review focuses on the aspects linking glucose and bone metabolism by offering insight into the most recent evidence in humans.

Uncarboxylated osteocalcin promotes osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells by activating the Erk-Smad/β-catenin signalling pathways

Uncarboxylated osteocalcin (unOc) is an osteoblast-derived hormone with multiple regulatory functions. Osteocalcin knockdown delays the maturation of mineral species and downregulates the expression of osteogenic-specific genes in human mesenchymal stromal cells. However, the underlying mechanisms remain unclear. Here, we investigated the effects of unOc on the osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs) and discovered that unOc promoted osteogenic differentiation of BMSCs, which was characterized by increases in alkaline phosphatase (ALP) activity, type I collagen (COLI) production, calcified nodule formation, and expression of osteogenic-specific genes including the osterix, runt-related transcription factor 2 (Runx2), ALP, and COLI genes. Further experiments indicated that unOc promoted the osteogenic differentiation of BMSCs via activation of the Erk-Smad/β-catenin signalling pathways. SIGNIFICANCE OF THE STUDY: Osteoporosis is associated with the osteogenic differentiation of BMSCs. In recent years, the role of unOc function as an endocrine hormone has received much attention. In this study, we reported for the first time that unOc promoted the osteogenic differentiation of mouse BMSCs through Erk-Smad/β-catenin signalling pathway. Our results highlight the importance of unOc as a hormone in promoting the osteogenic differentiation of BMSCs, indicating that this hormone may be beneficial in treatments for osteoporosis and fracture healing.

Bone Metabolism Parameters in Hemodialysis Patients With Chronic Kidney Disease and in Patients After Kidney Transplantation

Chronic kidney disease adversely affects the structure and metabolism of bone tissue, which may be a result of disturbed biochemical processes in adipose tissue. Renal replacement therapy is a life-saving therapy but it does not restore all metabolic functions and sometimes even escalates some disturbances. The study included 126 subjects: 47 hemodialysis patients (HD), 56 patients after renal transplantation (Tx) and 23 healthy controls (K). Bone density at the femoral neck (FN) and lumbar spine (LS), as well as body composition (adipose tissue content and lean body mass) were measured in each patient using the DXA method. In addition, serum concentrations of glucose, calcium, phosphorus, parathormone, FGF23, Klotho, osteocalcin, leptin, adiponectin and 1,25-dihydroxyvitamin D3 were measured. We observed significantly higher concentrations of leptin, FGF23 and Klotho proteins in the HD patients (77.2±48.1 ng/ml, 54.7±12.4 pg/ml, 420.6±303.8 ng/ml, respectively) and the Tx group (33.2±26.5 ng/ml; 179.8±383.9 pg/ml; 585.4±565.7, respectively) compared to the control group (24.4±24.6 ng/ml, 43.3±37.3 pg/ml, 280.5±376.0 ng/ml). Significantly lower bone density at FN was observed in the HD and Tx patients in comparison to the controls and in the HD patients compared to the Tx group. There were no significant differences in body mass composition between the studied groups. The results of this study indicate that both hemodialysis and transplantation are associated with increased serum concentrations of leptin, FGF23 and Klotho proteins, as well as lower bone density at femoral neck.

Glutamine Metabolism Is Essential for Stemness of Bone Marrow Mesenchymal Stem Cells and Bone Homeostasis

Skeleton has emerged as an endocrine organ which is both capable of regulating energy metabolism and being a target for it. Glutamine is the most bountiful and flexible amino acid in the body which provides adenosine 5′-triphosphate (ATP) demands for cells. Emerging evidences support that glutamine which acts as the second metabolic regulator after glucose exerts crucial roles in bone homeostasis at cellular level, including the lineage allocation and proliferation of bone mesenchymal stem cells (BMSCs), the matrix mineralization of osteoblasts, and the biosynthesis in chondrocytes. The integrated mechanism consisting of WNT, mammalian target of rapamycin (mTOR), and reactive oxygen species (ROS) signaling pathway in a glutamine-dependent pattern is responsible to regulate the complex intrinsic biological process, despite more extensive molecules are deserved to be elucidated in glutamine metabolism further. Indeed, dysfunctional glutamine metabolism enhances the development of degenerative bone diseases, such as osteoporosis and osteoarthritis, and glutamine or glutamine progenitor supplementation can partially restore bone defects which may promote treatment of bone diseases, although the mechanisms are not quite clear. In this review, we will summarize and update the latest research findings and clinical trials on the crucial regulatory roles of glutamine metabolism in BMSCs and BMSC-derived bone cells, also followed with the osteoclasts which are important in bone resorption.

Osteokines and the vasculature: a review of the in vitro effects of osteocalcin, fibroblast growth factor-23 and lipocalin-2

Bone-derived factors that demonstrate extra-skeletal functions, also termed osteokines, are fast becoming a highly interesting and focused area of cross-disciplinary endocrine research. Osteocalcin (OCN), fibroblast growth factor-23 (FGF23) and lipocalin-2 (LCN-2), produced in bone, comprise an important endocrine system that is finely tuned with other organs to ensure homeostatic balance and health. This review aims to evaluate in vitro evidence of the direct involvement of these proteins in vascular cells and whether any causal roles in cardiovascular disease or inflammation can be supported. PubMed, Medline, Embase and Google Scholar were searched for relevant research articles investigating the exogenous addition of OCN, FGF23 or LCN-2 to vascular smooth muscle or endothelial cells. Overall, these osteokines are directly vasoactive across a range of human and animal vascular cells. Both OCN and FGF23 have anti-apoptotic properties and increase eNOS phosphorylation and nitric oxide production through Akt signalling in human endothelial cells. OCN improves intracellular insulin signalling and demonstrates protective effects against endoplasmic reticulum stress in murine and human endothelial cells. OCN may be involved in calcification but further research is warranted, while there is no evidence for a pro-calcific effect of FGF23 in vitro. FGF23 and LCN-2 increase proliferation in some cell types and increase and decrease reactive oxygen species generation, respectively. LCN-2 also has anti-apoptotic effects but may increase endoplasmic reticulum stress as well as have pro-inflammatory and pro-angiogenic properties in human vascular endothelial and smooth muscle cells. There is no strong evidence to support a pathological role of OCN or FGF23 in the vasculature based on these findings. In contrast, they may in fact support normal endothelial functioning, vascular homeostasis and vasodilation. No studies examined whether OCN or FGF23 may have a role in vascular inflammation. Limited studies with LCN-2 indicate a pro-inflammatory and possible pathological role in the vasculature but further mechanistic data is required. Overall, these osteokines pose intriguing functions which should be investigated comprehensively to assess their relevance to cardiovascular disease and health in humans.

Altered vertebral and femoral bone structure in juvenile offspring of microswine subject to maternal low protein nutritional challenge

Epidemiological studies suggest skeletal growth is programmed during intrauterine and early postnatal life. We hypothesize that bone development may be altered by maternal diet and have investigated this using a microswine model of maternal protein restriction (MPR). Mothers were fed a control diet (14% protein) or isocaloric low (1%) protein diet during late pregnancy and for 2 weeks postnatally. Offspring were weaned at 4 weeks of age to ad lib or calorie-restricted food intake groups. Femur and vertebra were analysed by micro computed tomography in offspring 3-5 months of age. Caloric restriction from 4 weeks of age, designed to prevent catch-up growth, showed no significant effects on bone structure in the offspring from either maternal dietary group. A maternal low protein diet altered trabecular number in the proximal femur and vertebra in juvenile offspring. Cortical bone was unaffected. These results further support the need to understand the key role of the nutritional environment in early development on programming of skeletal development and consequences in later life.

The effect of metformin versus placebo in combination with insulin analogues on bone mineral density and trabecular bone score in patients with type 2 diabetes mellitus: a randomized placebo-controlled trial

Some antihyperglycemic medications have been found to affect bone metabolism. We assessed the long-term effects of metformin compared with placebo on bone mineral density (BMD) and trabecular bone score (TBS) in patients with type 2 diabetes. Metformin had no significant effect on BMD in the spine and hip or TBS compared with a placebo.

INTRODUCTION

Patients with type 2 diabetes mellitus (T2DM) have an increased risk of fractures despite a high bone mass. Some antihyperglycemic medications have been found to affect bone metabolism. We assessed the long-term effects of metformin compared with placebo on bone mineral density (BMD) and trabecular bone score (TBS).

METHODS

This was a sub-study of a multicenter, randomized, 18-month placebo-controlled, double-blinded trial with metformin vs. placebo in combination with different insulin regimens (the Copenhagen Insulin and Metformin Therapy trial) in patients with T2DM. BMD in the spine and hip and TBS in the spine were assessed by dual-energy X-ray absorptiometry at baseline and after 18 months follow-up.

RESULTS

Four hundred seven patients were included in this sub-study. There were no between-group differences in BMD or TBS. From baseline to 18 months, TBS decreased significantly in both groups (metformin group, - 0.041 [- 0.055, - 0.027]; placebo group - 0.046 [- 0.058, - 0.034]; both p < 0.001). BMD in the spine and total hip did not change significantly from baseline to 18 months. After adjustments for gender, age, vitamin D, smoking, BMI, duration of T2DM, HbA1c, and insulin dose, the TBS between-group differences increased but remained non-significant. HbA_1c was negatively associated with TBS (p = 0.009) as was longer duration of diabetes, with the femoral neck BMD (p = 0.003). Body mass index had a positive effect on the hip and femoral neck BMD (p < 0.001, p = 0.045, respectively).

CONCLUSIONS

Eighteen months of treatment with metformin had no significant effect on BMD in the spine and hip or TBS in patients with T2DM compared with a placebo. TBS decreased significantly in both groups.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT00657943).

Biochemical Markers of Bone Turnover and Risk of Incident Diabetes in Older Women: The Cardiovascular Health Study

OBJECTIVE

To investigate the relationship of osteocalcin (OC), a marker of bone formation, and C-terminal cross-linked telopeptide of type I collagen (CTX), a marker of bone resorption, with incident diabetes in older women.

RESEARCH DESIGN AND METHODS

The analysis included 1,455 female participants from the population-based Cardiovascular Health Study (CHS) (mean [SD] age 74.6 [5.0] years). The cross-sectional association of serum total OC and CTX levels with insulin resistance (HOMA-IR) was examined using multiple linear regression. The longitudinal association of both markers with incident diabetes, defined by follow-up glucose measurements, medications, and ICD-9 codes, was examined using multivariable Cox proportional hazards models.

RESULTS

OC and CTX were strongly correlated (r = 0.80). In cross-sectional analyses, significant or near-significant inverse associations with HOMA-IR were observed for continuous levels of OC (β = -0.12 per SD increment; P = 0.004) and CTX (β = -0.08 per SD; P = 0.051) after full adjustment for demographic, lifestyle, and clinical covariates. During a median follow-up of 11.5 years, 196 cases of incident diabetes occurred. After full adjustment, both biomarkers exhibited inverse associations with incident diabetes (OC: hazard ratio 0.85 per SD [95% CI 0.71-1.02; P = 0.075]; CTX: 0.82 per SD [0.69-0.98; P = 0.031]), associations that were comparable in magnitude and approached or achieved statistical significance.

CONCLUSIONS

In late postmenopausal women, lower OC and CTX levels were associated with similarly increased risks of insulin resistance at baseline and incident diabetes over long-term follow-up. Further research to delineate the mechanisms linking abnormal bone homeostasis and energy metabolism could uncover new approaches for the prevention of these age-related disorders.

Beta cell stress in a 4-year follow-up of patients with type 2 diabetes: A longitudinal analysis of the BetaDecline Study

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with a progressive deterioration in beta cell function and loss of glycaemic control. Clinical predictors of beta cell failure are needed to guide appropriate therapy.

METHODS

A prospective evaluation of a large set of potential predictors of beta cell stress, measured as change in the proinsulin/insulin (PI/I) ratio, was conducted in a cohort of 235 outpatients with T2DM on stable treatment with oral hypoglycaemic agents or diet followed up for ~4 years (median value 3.9 years; interquartile range 3.8-4.1 years).

RESULTS

Overall, metabolic control deteriorated over time, with a significant increase in glycated haemoglobin (HbA1c; P < .0001), proinsulin (P < .0001), and PI/I ratio (P = .001), without significant changes in the homeostatic model assessment of insulin resistance. Multivariate regression analysis showed that for each 1% (10.9 mmol/mol) increase from baseline in HbA1c, the risk of beta cell stress increased by 3.8 times; for each 1% (10.9 mmol/mol) incremental increase in HbA1c during the study, risk of beta cell stress increased by 2.25 times that at baseline. By contrast, baseline anthropometric and clinical variables, lipid profile, inflammatory markers (PCR, IL-6), non-esterified fatty acids, and current therapies did not independently influence PI/I ratio variation during follow-up.

CONCLUSIONS

In this cohort of patients with T2DM, beta cell function progressively deteriorated despite current therapies. Among a large set of clinical and biochemical predictors, only baseline HbA1c levels and their deterioration overtime were associated with higher beta cell stress over time.