Time-updated Fibroblast Growth Factor 23 Is Predictive for Posttransplant Diabetes Mellitus in Kidney Transplant Recipients.

Objective: This work aimed to study whether fibroblast growth factor 23 (FGF23) is predictive for incident posttransplant diabetes mellitus (PTDM) in kidney transplant recipients (KTRs). Methods: We repeatedly analyzed plasma C-terminal FGF23 concentrations in 170 KTRs enrolled in the TransplantLines Biobank and Cohort Study. Associations of time-updated plasma FGF23 with incident PTDM were studied by Cox regression. Results: A total of 170 KTRs (46% female, aged 54.4 ± 12.4 years) with 540 FGF23 measurements were included. Plasma FGF23 concentrations at transplantation were 31.1 (0.76-2576) pmol/L. During a follow-up of 24 (12-24) months, 38 patients developed PTDM. The highest FGF23 tertile (compared to the lowest) was associated with an increased risk for PTDM (fully adjusted hazard ratio 20.9; 95% CI, 3.4-130.0; P < .001). Conclusion: In KTRs without diabetes at baseline, the highest tertile of FGF23, compared to the lowest, is predictive for development of PTDM.

Serum T50 predicts cardiovascular mortality in individuals with type 2 diabetes: A prospective cohort study.

BACKGROUND AND AIMS: Individuals with type 2 diabetes (T2D) have a higher risk of cardiovascular disease, compared with those without T2D. The serum T50 test captures the transformation time of calciprotein particles in serum. We aimed to assess whether serum T50 predicts cardiovascular mortality in T2D patients, independent of traditional risk factors. METHODS: We analyzed 621 individuals with T2D in this prospective cohort study. Cox regression models were performed to test the association between serum T50 and cardiovascular and all-cause mortality. Causes of death were categorized according to ICD-10 codes. Risk prediction improvement was assessed by comparing Harrell's C for models without and with T50. RESULTS: The mean age was 64.2 ± 9.8 years, and 61% were male. The average serum T50 time was 323 ± 63 min. Higher age, alcohol use, high-sensitive C-reactive protein, and plasma phosphate were associated with lower serum T50 levels. Higher plasma triglycerides, venous bicarbonate, sodium, magnesium, and alanine aminotransferase were associated with higher serum T50 levels. After a follow-up of 7.5[5.4-10.7] years, each 60 min decrease in serum T50 was associated with an increased risk of cardiovascular (fully adjusted HR 1.32, 95% CI 1.08-1.50, and p = 0.01) and all-cause mortality (HR 1.15, 95%CI 1.00-1.38, and p = 0.04). Results were consistent in sensitivity analyses after exclusion of individuals with estimated glomerular filtration rate <45 or <60 mL/min/1.73 m2 and higher plasma phosphate levels. CONCLUSIONS: Serum T50 improves prediction of cardiovascular and all-cause mortality risk in individuals with T2D. Serum T50 may be useful for risk stratification and to guide therapeutic strategies aiming to reduce cardiovascular mortality in T2D.

Pre-Transplant Hyperparathyroidism and Graft or Patient Outcomes After Kidney Transplantation.

The impact of pre-transplant parathyroid hormone (PTH) levels on early or long-term kidney function after kidney transplantation is subject of debate. We assessed whether severe hyperparathyroidism is associated with delayed graft function (DGF), death-censored graft failure (DCGF), or all-cause mortality. In this single-center cohort study, we studied the relationship between PTH and other parameters related to bone and mineral metabolism, including serum alkaline phosphatase (ALP) at time of transplantation with the subsequent risk of DGF, DCGF and all-cause mortality using multivariable logistic and Cox regression analyses. In 1,576 kidney transplant recipients (51.6 ± 14.0 years, 57.3% male), severe hyperparathyroidism characterized by pre-transplant PTH ≥771 pg/mL (>9 times the upper limit) was present in 121 patients. During 5.2 [0.2-30.0] years follow-up, 278 (15.7%) patients developed DGF, 150 (9.9%) DCGF and 432 (28.6%) died. A higher pre-transplant PTH was not associated with DGF (HR 1.06 [0.90-1.25]), DCGF (HR 0.98 [0.87-1.13]), or all-cause mortality (HR 1.02 [0.93-1.11]). Results were consistent in sensitivity analyses. The same applied to other parameters related to bone and mineral metabolism, including ALP. Severe pre-transplant hyperparathyroidism was not associated with an increased risk of DGF, DCGF or all-cause mortality, not supporting the need of correction before kidney transplantation to improve graft or patient survival.

Effect of high in comparison to low dairy intake intervention on markers of bone and cartilage remodeling and phosphate metabolism in healthy adults with overweight.

BACKGROUND: In the ageing population, issues with bone and joint health are highly prevalent. Both beneficial and potential risks of dairy products on bone and joint health are reported in epidemiological studies. Furthermore, the phosphorus (P) load from dairy could potentially lead to unfavorable changes in P metabolism. OBJECTIVE: To investigate the effect of dairy intake on markers of bone and joint metabolism and P metabolism in an intervention study with high and low dairy intake. METHODS: In a post hoc analysis of a randomized cross-over trial with overweight adults, the effect of a standardized high dairy intake [HDI (5-6 dairy portions per day) versus low dairy intake (LDI, ≤ 1 dairy portion/day)] for 6 weeks on markers of bone and joint health was assessed using enzyme-linked immunosorbent assays and electrochemiluminescence immunoassays. Markers indicative for cartilage breakdown, including urinary CTX-II, serum COMP and 4-hydroxyproline, and markers indicative for bone remodeling, such as serum CTX-I, PTH, 25(OH)D, osteocalcin, P1NP and FGF23, were investigated using linear mixed models. Furthermore, changes in P metabolism, including the main phosphate-regulating hormone FGF23 were explored. RESULTS: This study was completed by 46 adults (57% female, age 59 ± 4 years, BMI 28 ± 2 kg/m2). Following HDI, markers such as urinary CTX-II excretion, COMP, 25(OH)D, PTH and CTX-I were significantly lower after HDI, as compared to LDI. For example, CTX-II excretion was 1688 ng/24 h at HDI, while it was 2050 ng/24 h at LDI (p < 0.001). Concurrently, P intake was higher at HDI than at LDI (2090 vs 1313 mg/day, p < 0.001). While plasma P levels did not differ (1.03 vs 1.04 mmol/L in LDI, p = 0.36), urinary P excretion was higher at HDI than at LDI (31 vs 28 mmol/L, p = 0.04). FGF23 levels tended to be higher at HDI than at LDI (76.3 vs. 72.9 RU/mL, p = 0.07). CONCLUSIONS: HDI, as compared to LDI, reduced markers that are indicative for joint and bone resorption and bone turnover. No changes in P metabolism were observed. CLINICAL TRIAL REGISTRY: This trial was registered at https://trialsearch.who.int/Trial2.aspx?TrialID=NTR4899 as NTR4899.

Fibroblast growth factor 23 and calcium-phosphate metabolism in relation to cardiovascular risk factors in patients with type 1 diabetes.

BACKGROUND: Cardiovascular disease (CVD) is the major cause of mortality in type 1 diabetes (T1D). The objective of this study is to evaluate fibroblast growth factor 23 (FGF23) and calcium-phosphate metabolism in relation to cardiovascular risk factors in adults with and without T1D. METHODS: A case-control study was conducted using data from patients with T1D and age- and sex matched controls without T1D from the Lifelines Cohort Study. RESULTS: We included 302 adults in the T1D group and 302 adults in the control group. Median age was 42 years. Median glycosylated hemoglobin (HbA1c) in the T1D group was 7.8%. FGF23 of all patients with T1D was not significantly different from controls. Females with T1D had significantly higher FGF23 than males with T1D (83.3 vs 69.3 U/mL, p = 0.002), this was not observed in controls. Serum phosphate, calcium, and alkaline phosphatase were higher and parathyroid hormone was lower in patients with T1D, compared to controls (all p < .001), all within normal range. In the T1D group, FGF23 was positively correlated with serum phosphate (p < .001), alkaline phosphatase (p = .01), and calcium (p = .030), these correlations were not observed in controls. Median FGF23 was significantly higher in current smokers than in nonsmokers with T1D (84.9 vs 73.5 U/mL, p < .05). CONCLUSIONS: Serum calcium, phosphate, and alkaline phosphatase were higher in patients with T1D than in controls and were positively correlated to FGF23 in patients with T1D. Current smokers with T1D had higher FGF23 than nonsmokers with T1D. These findings may contribute to the increased risk of CVD in patients with T1D.

NT-proBNP Mediates the Association Between FGF23 and All-Cause Mortality in Individuals With Type 2 Diabetes.

BACKGROUND: FGF23 (fibroblast growth factor 23) is associated with a higher mortality risk in type 2 diabetes, but the mechanism is unclear. We aimed to study whether NT-proBNP (N-terminal pro-brain natriuretic peptide) mediates the association between FGF23 and mortality. METHODS AND RESULTS: We analyzed C-terminal FGF23 and NT-proBNP levels in 399 patients with type 2 diabetes. Cox regression analyses were performed, followed by mediation analyses using Structural Equation Modeling. During follow-up of 9.2 [7.6-11.3] years, 117 individuals died. FGF23 was associated with all-cause mortality, independent of potential confounders (fully adjusted hazard ratio [HR], 2.32 [95% CI, 1.21-4.43], P=0.01). The association was lost upon further adjustment for NT-proBNP (HR, 1.84; 95% CI, 0.91-3.73). NT-proBNP accounted for 26% of the mediation effect between FGF23 and all-cause mortality. CONCLUSIONS: These findings suggest that a higher FGF23 level is associated with increased mortality in individuals with type 2 diabetes through an effect on volume homeostasis.

Fibroblast Growth Factor 23, Glucose Homeostasis, and Incident Diabetes: Findings of 2 Cohort Studies.

CONTEXT: The phosphate-regulating hormone fibroblast growth factor 23 (FGF23) has been linked to deregulations in glucose metabolism, but its role is insufficiently understood. OBJECTIVE: This study investigates potential crosstalk between FGF23 and glucose homeostasis. METHODS: First, we investigated the effect of glucose loading on plasma C-terminal FGF23 levels and its temporal relationship with changes in plasma phosphate in 45 overweight (body mass index [BMI] 25-30) individuals using time-lag analyses. Second, we studied cross-sectional associations of plasma C-terminal FGF23 levels with glucose homeostasis using multivariable linear regression in a population-based cohort. We also investigated associations of FGF23 with incident diabetes and obesity (BMI > 30) in individuals without diabetes or obesity at baseline, respectively, using multivariable Cox regression analyses. Finally, we explored whether the association between FGF23 and diabetes depends on BMI. RESULTS: After glucose loading, changes in FGF23 preceded changes in plasma phosphate (Ptime-lag = .04). In the population-based cohort (N = 5482; mean age 52 years, 52% women, median FGF23 69 RU/mL), FGF23 was associated with plasma glucose (ß = .13 [.03-.23]; P = .01), insulin (ß = .10 [.03-.17]; P < .001), and proinsulin (ß = .06 [0.02-0.10]; P = .01) at baseline. On longitudinal analyses, a higher baseline FGF23 was independently associated with development of diabetes (199 events [4%]; fully adjusted hazard ratio [HR] 1.66 [95% CI, 1.06-2.60]; P = .03) and development of obesity (241 events [6%]; fully adjusted HR 1.84 [95% CI, 1.34-2.50]; P < .001). The association between FGF23 and incident diabetes lost significance after additional adjustment for BMI. CONCLUSION: Glucose loading has phosphate-independent effects on FGF23 and, vice versa, FGF23 is associated with glucose, insulin and proinsulin levels, and obesity. These findings suggest crosstalk between FGF23 and glucose homeostasis, which may promote susceptibility to incident diabetes.

Plasma levels of GlycA, a pro-inflammatory glycoprotein biomarker, associate with an increased risk of microvascular complications in patients with type 2 diabetes (Zodiac-62).

PURPOSE: GlycA, a pro-inflammatory glycoprotein biomarker, associates with newly developed type 2 diabetes (T2D). We determined the association of plasma GlycA with the development of microvascular complications in patients with established T2D. METHODS: Plasma GlycA was measured by nuclear magnetic resonance spectrometry in T2D patients without microvascular complications at baseline (n = 145) participating in a longitudinal cohort study of primary care-treated T2D patients (Zwolle Outpatient Diabetes project Integrating Available Care (ZODIAC) study). Associations of GlycA with incident microvascular complications including nephropathy, retinopathy, and neuropathy, were determined by Cox proportional hazards regression analyses. RESULTS: After a median follow-up of 3.2 (interquartile range [IQR]: 2.9-3.4) years, 49 patients (33.8%) developed one or more microvascular complications. Median GlycA levels were 453.5 (IQR: 402.0-512.8) µmol/l. GlycA was associated with incident microvascular complications (hazard ratio [HR] per 1-SD increment: 1.28 [95% confidence interval [CI]:1.00-1.63], P = 0.048]), even after adjustment for potential confounders and high-sensitive C-reactive protein (hs-CRP), HR 1.79 [95%CI:1.25-2.57], P = 0.001). In contrast, hs-CRP levels were not significantly associated with the risk of developing microvascular complications (P = 0.792). CONCLUSION: Higher plasma GlycA is associated with an increased risk of developing microvascular complications in T2D patients. Altered N-glycan branching associated with acute-phase reactive proteins may represent a preferred biomarker of systemic low-grade inflammation in predicting diabetic complications.

The Paradoxical Role of Circulating Ketone Bodies in Glycemic Control of Individuals with Type 2 Diabetes: High Risk, High Reward?

INTRODUCTION: Fasting plasma ketone bodies (KB) are elevated in individuals with type 2 diabetes (T2D) and could affect glycemic control and disease progression. Prolonged KB exposure may result in adaptive beneficial responses, counteracting glycemic dysregulation. In the current proof-of-concept study in adults with T2D, we hypothesized that fasting plasma KB are cross-sectionally associated with poorer glycemic control but prospectively with better glycemic control. MATERIALS AND METHODS: Fasting plasma KB were measured via nuclear magnetic resonance spectroscopy in patients with T2D treated in primary care (Zodiac cohort; The Netherlands). We analyzed the associations between KB and HbA1c at baseline using linear regression analyses and HbA1c changes over time using linear mixed models. We adjusted for potential confounders, including risk factors for poor glycemic control. Individuals with T2D participating in the general population-based PREVEND study were used as a replication cohort. RESULTS: We included 271 individuals with T2D with a total of 859 HbA1c measurements during a follow-up period of 3.0 (2.0-3.2) years. At baseline, the total amount of fasting plasma KB was independently and positively associated with HbA1c levels (regression coefficient in the fully adjusted analysis = 0.31; 95% CI 0.06-0.57, per doubling of KB; p = 0.02). In contrast, in the longitudinal analyses, fasting plasma KB were associated with a yearly HbA1c (%) decrease of -0.10 (95% CI -0.19 to -0.00 per doubling baseline KB; p = 0.05). Results were replicated in 387 individuals with T2D from a general population cohort with a total of 1115 glucose measurements during a follow-up period of 7.5 (7.2-8.0) years. A yearly decrease in fasting plasma glucose (mmol/L) of 0.09 was found per doubling of baseline KB. CONCLUSIONS: This study is the first to suggest a paradoxical role of circulating KB on glycemic control in T2D: elevated KB are associated with cross-sectionally poorer glycemic control but longitudinally with better long-term glycemic control.

Plasma phosphate and all-cause mortality in individuals with and without type 2 diabetes: the Dutch population-based lifelines cohort study.

INTRODUCTION: Individuals with type 2 diabetes have a substantially elevated cardiovascular risk. A higher plasma phosphate level promotes vascular calcification, which may adversely affect outcomes in individuals with type 2 diabetes. We hypothesized that the association between plasma phosphate and all-cause mortality is stronger in individuals with type 2 diabetes, compared to those without diabetes. METHODS: We analysed the association between plasma phosphate and all-cause mortality in the Dutch population-based Lifelines cohort and in subgroups with and without type 2 diabetes, using multivariable Cox regression adjusted for potential confounders. Effect modification was tested using multiplicative interaction terms. RESULTS: We included 57,170 individuals with 9.4 [8.8-10.4] years follow-up. Individuals within the highest phosphate tertile (range 1.00-1.83 mmol/L) were at higher risk of all-cause mortality (fully adjusted HR 1.18 [95% CI 1.02-1.36], p = 0.02), compared with the intermediate tertile (range 0.85-0.99 mmol/L). We found significant effect modification by baseline type 2 diabetes status (p-interaction = 0.003). Within the type 2 diabetes subgroup (N = 1790), individuals within the highest plasma phosphate tertile had an increased mortality risk (HR 1.73 [95% CI 1.10-2.72], p = 0.02 vs intermediate tertile). In individuals without diabetes at baseline (N = 55,380), phosphate was not associated with mortality (HR 1.12 [95% CI 0.96-1.31], p = 0.14). Results were similar after excluding individuals with eGFR < 60 mL/min/1.73 m2. DISCUSSION: High-normal plasma phosphate levels were associated with all-cause mortality in individuals with type 2 diabetes. The association was weaker and non-significant in those without diabetes. Measurement of phosphate levels should be considered in type 2 diabetes; whether lowering phosphate levels can improve health outcomes in diabetes requires further study.

Phosphate and fibroblast growth factor 23 in diabetes.

Diabetes is associated with a strongly elevated risk of cardiovascular disease, which is even more pronounced in patients with diabetic nephropathy. Currently available guideline-based efforts to correct traditional risk factors are only partly able to attenuate this risk, underlining the urge to identify novel treatment targets. Emerging data point towards a role for disturbances in phosphate metabolism in diabetes. In this review, we discuss the role of phosphate and the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) in diabetes. We address deregulations of phosphate metabolism in patients with diabetes, including diabetic ketoacidosis. Moreover, we discuss potential adverse consequences of these deregulations, including the role of deregulated phosphate and glucose as drivers of vascular calcification propensity. Finally, we highlight potential treatment options to correct abnormalities in phosphate and FGF23. While further studies are needed to more precisely assess their clinical impact, deregulations in phosphate and FGF23 are promising potential target in diabetes and diabetic nephropathy.

Incidence and determinants of hypophosphatemia in diabetic ketoacidosis: an observational study.

INTRODUCTION: Diabetic ketoacidosis (DKA) is a life-threatening complication of type 1 diabetes mellitus (T1DM) characterized by hyperglycemia and metabolic acidosis. Hypophosphatemia in DKA often occurs during hospital admittance for DKA. Literature on the magnitude, determinants and consequences of hypophosphatemia in DKA is scarce. Primary aim of this study was to investigate the incidence and consequences of hypophosphatemia during hospitalisation for DKA. RESEARCH DESIGN AND METHODS: Cohort study among individuals with T1DM who were admitted for DKA between 2005 and 2020 in an academic and a non-academic hospital. Multivariate regression models were performed to investigate determinants of the lowest phosphate during the treatment of DKA. RESULTS: A total of 127 episodes of DKA among 80 individuals were identified. Age at DKA presentation was 28 (22-46) years, 45% of the cases was female, diabetes duration was 13.2 (8.9-25.5) years with glycosylated hemoglobin levels of 91.9±26.2 mmol/mol. In 9% of all cases, DKA was the first presentation of T1DM. Lowest phosphate levelss reported during the treatment phase were 0.54 (0.32-0.83) mmol/L and hypophosphatemia was present in 74% (62/84). The time to lowest phosphate was 16 (8-23) hours. In multivariate analysis, baseline bicarbonate and hemoglobin at admission were significantly associated with the lowest phosphate level reported. No adverse effects of hypophosphatemia on hospital stay duration, morbidity or mortality were found, even if left untreated. CONCLUSIONS: Hypophosphatemia during DKA is common and increases with severe acidosis. However, in this study it was not related to adverse outcomes. Although limitations of this retrospective study should be taken into account, the routine and repeated measurement of phosphate levels in DKA could be reconsidered, provided that possible symptoms related to hypophosphatemia are monitored.

Serum calcification propensity is associated with HbA1c in type 2 diabetes mellitus.

INTRODUCTION: Serum calcification propensity is emerging as an independent predictor for cardiovascular outcomes in high-risk populations. Calcification propensity can be monitored by the maturation time of calciprotein particles in serum (T50 test). A low T50 value is an independent determinant of cardiovascular morbidity and mortality in various populations. Aim was to investigate the T50 and its relationship to type 2 diabetes mellitus. RESEARCH DESIGN AND METHODS: Using nephelometry, serum T50 was cross-sectionally measured in 932 stable patients with type 2 diabetes mellitus (55% male) with a median age of 66 (62-75) years, diabetes duration of 6.5 (3.0-10.2) years and hemoglobin A1c (HbA1c) of 49 (44-54) mmol/mol. RESULTS: Serum T50 was normally distributed with a mean value of 261±66 min. In linear regression, serum T50 was lower in women and current smokers. A lower T50 value was found in patients with a higher HbA1c or higher systolic blood pressure, insulin users and patients with a longer history of diabetes. The association with HbA1c was independent of other determinants in multivariable analysis. There was no association between T50 and previous macrovascular events or the presence of microvascular disease. CONCLUSIONS: Serum calcification propensity is independently associated with glycemic control, suggesting that a lower HbA1c may be associated with better cardiovascular outcomes. Retrospective analysis could not establish an association between a history of macrovascular events and T50, and prospective studies will have to be performed to address this hypothesis. TRIAL REGISTRATION NUMBER: NCT01570140.