Bone mineral density spectrum in individuals with type 1 diabetes, latent autoimmune diabetes in adults, and type 2 diabetes

Genetically determined type 1 diabetes mellitus and risk of osteoporosis

BACKGROUND

Observational evidence suggests that type 1 diabetes mellitus (T1DM) is associated with the risk of osteoporosis (OP). Nevertheless, it is not apparent whether these correlations indicate a causal relationship. To elucidate the causal relationship, a two-sample Mendelian randomization (MR) analysis was performed.

METHODS

T1DM data was obtained from the large genome-wide association study (GWAS), in which 6683 cases and 12,173 controls from 12 European cohorts were involved. Bone mineral density (BMD) samples at four sites were extracted from the GEnetic Factors for OSteoporosis (GEFOS) consortium, including forearm (FA) (n = 8,143), femoral neck (FN) (n = 32,735), lumbar spine (LS) (n = 28,498), and heel (eBMD) (n = 426,824). The former three samples were from mixed populations and the last one was from European. Inverse variance weighting, MR-Egger, and weighted median tests were used to test the causal relationship between T1DM and OP. A series of sensitivity analyses were then conducted to verify the robustness of the results.

RESULTS

Twenty-three independent SNPs were associated with FN-BMD and LS-BMD, twenty-seven were associated with FA-BMD, and thirty-one were associated with eBMD. Inverse variance-weighted estimates indicated a causal effect of T1DM on FN-BMD (odds ratio (OR) =1.033, 95 % confidence interval (CI): 1.012-1.054, p = 0.002) and LS-BMD (OR = 1.032, 95 % CI: 1.005-1.060, p = 0.022) on OP risk. Other MR methods, including weighted median and MR-Egger, calculated consistent trends. While no significant causation was found between T1DM and the other sites (FA-BMD: OR = 1.008, 95 % CI: 0.975-1.043, p = 0.632; eBMD: OR = 0.993, 95 % CI: 0.985-1.001, p = 0.106). No significant heterogeneity (except for eBMD) or horizontal pleiotropy was found for instrumental variables, suggesting these results were reliable and robust.

CONCLUSIONS

This study shows a causal relationship between T1DM and the risk of some sites of OP (FN-BMD, LS-BMD), allowing for continued research to discover the clinical and experimental mechanisms of T1DM and OP. It also contributes to the recommendation if patients with T1DM need targeted care to promote bone health and timely prevention of osteoporosis.

Bone Mineral Density and Vitamin D Status in Patients with Autoimmune Polyglandular Syndromes: A Single Tertiary Care Center Experience

Immunological abnormalities, the resulting endocrinopathies, and their treatments may impact bone health and 25-hydroxyvitamin D (25-OHD) in patients with autoimmune polyglandular syndromes (APS). Several etiologies contribute to increased risk for low bone mineral density (BMD), including vitamin D deficiency. This study evaluated the vitamin D level and BMD of patients with APS. We performed a cross-sectional study on 44 patients with APS and 55 age and gender-matched control subjects. Among patients with APS, 14 were classified as APS-2 [Addison's disease (AD)+autoimmune thyroid disease (ATD) and/or type 1 diabetes(T1D)]. In contrast, the other 30 were APS-3 (ATD+T1D+other autoimmune diseases). Serum samples were analyzed for vitamin D levels. The lumbar spine and femoral neck BMD were measured by dual X-ray absorptiometry. Z-scores were obtained by comparison with age- and gender-matched average values (both patients and controls). The accepted normal levels were Z-score>-1 and 25-OHD>30 ng/ml. Patients with APS showed 25-OHD levels and BMD significantly lower than healthy controls (p<0.001 and p<0.05, respectively). The highest prevalence of abnormal BMD was observed in the APS-2 subgroup (13 out of 14 patients, 92.6%). Identifying and treating vitamin D deficiency and low BMD is critical in APS patients. The fact that the significant endocrine component of APS-2 is AD, and these patients receive chronic long-term glucocorticoid therapy can be shown as the reason for this result. However, more extensive prospective controlled studies are needed to confirm these findings.

Association of C-peptide level with bone mineral density in type 2 diabetes mellitus

This study revealed that there was no significant linear relationship between fasting C-peptide (FCP) level and bone mineral density (BMD) or fracture risk in type 2 diabetes mellitus (T2DM) patients. However, in the FCP ≤ 1.14 ng/ml group, FCP is positively correlated with whole body (WB), lumbar spine (LS), and femoral neck (FN) BMD and negatively correlated with fracture risk.

PURPOSE

To explore the relationship between C-peptide and BMD and fracture risk in T2DM patients.

METHODS

530 T2DM patients were enrolled and divided into three groups by FCP tertiles, and the clinical data were collected. BMD was measured by dual-energy X-ray absorptiometry (DXA). The 10-year probability of major osteoporotic fractures (MOFs) and hip fractures (HFs) was evaluated by adjusted fracture risk assessment tool (FRAX).

RESULTS

In the FCP ≤ 1.14 ng/ml group, FCP level was positively correlated with WB, LS, and FN BMD, while FCP was negatively correlated with fracture risk and osteoporotic fracture history. However, FCP was not correlated with BMD and fracture risk and osteoporotic fracture history in the 1.14 < FCP ≤ 1.73 ng/ml and FCP > 1.73 ng/ml groups. The study has shown that FCP was an independent factor influencing BMD and fracture risk in the FCP ≤ 1.14 ng/ml group.

CONCLUSIONS

There is no significant linear relationship between FCP level and BMD or fracture risk in T2DM patients. In the FCP ≤ 1.14 ng/ml group, FCP is positively correlated with WB, LS, and FN BMD and negatively correlated with fracture risk, and FCP is an independent influencing factor of BMD and fracture risk. The findings suggest that FCP may predict the risk of osteoporosis or fracture in some T2DM patients, which has a certain clinical value.

Causal relationship between Type 1 diabetes and osteoporosis and fracture occurrence: a two-sample Mendelian randomization analysis

We used two-sample Mendelian Randomization to reveal causal estimates of type 1 diabetes and bone. Type 1 diabetes was found to be a risk factor for bone metabolic health, although there was no clear evidence to support a genetic association between type 1 diabetes and osteoporosis and fracture risk.

INTRODUCTION

Based on the random assignment of gametes at conception, Mendelian randomization (MR) analysis simulates randomized controlled trials in an observational setting. Therefore, we used MR to assess the association causality of type 1 diabetes (T1D) with fractures and osteoporosis.

METHODS

From a genome-wide association meta-analysis, independent single nucleotide polymorphisms closely associated with T1D were selected as instrumental variables. Data on fracture and osteoporosis were obtained from the FinnGen Consortium. We performed a two-sample MR analysis, using inverse-variance weighted (IVW) as the primary analysis method, to assess possible causal associations between T1D and bone risk. The results were verified by MR-Egger regression and median weighted method (WME). MR-PRESSO and MR-Egger intercepts were used to evaluate the horizontal pleiotropy of instrumental variables, and the Q-test and "leave-one-out" methods were used to test the heterogeneity of MR results.

RESULTS

IVW (OR=1.040, 95% CI=0.974-1.109, P=0.238), MR-Egger regression (OR=1.077, 95% CI=0.921-1.260, P=0.372) and WME (OR=1.021, 95% CI=0.935-1.114, P=0.643) all showed that there was no causal relationship between T1D and osteoporosis, but the direction was consistent. The indicative significance of IVW results in T1D and forearm fractures (OR=1.062, 95% CI=1.010-1.117, P=0.020), but the results are not robust enough. There was no causal effect in femur, lumbar and pelvis, or shoulder and upper arm fractures.

CONCLUSIONS

After MR analysis, although T1D may be a risk factor for bone health, we do not have sufficient evidence to support a causal effect of T1D on osteoporosis and fractures at a genetically predicted level. More cases need to be included for analysis.

Latent autoimmune diabetes in adults in China

Latent autoimmune diabetes in adults (LADA) is a type of diabetes caused by slow progression of autoimmune damage to pancreatic beta cells. According to the etiological classification, LADA should belong to the autoimmune subtype of type 1 diabetes (T1D). Previous studies have found general immune genetic effects associated with LADA, but there are also some racial differences. Multicenter studies have been conducted in different countries worldwide, but it is still unclear how the Chinese and Caucasian populations differ. The epidemiology and phenotypic characteristics of LADA may vary between Caucasian and Chinese diabetic patients as lifestyle, food habits, and body mass index differ between these two populations. The prevalence of LADA in China has reached a high level compared to other countries. The prevalence of LADA in China has reached a high level compared to other countries, and the number of patients with LADA ranks first in the world. Previous studies have found general immune genetic effects associated with LADA, but some racial differences also exist. The prevalence of LADA among newly diagnosed type 2 diabetes patients over the age of 30 years in China is 5.9%, and LADA patients account for 65% of the newly diagnosed T1D patients in the country. As a country with a large population, China has many people with LADA. A summary and analysis of these studies will enhance further understanding of LADA in China. In addition, comparing the similarities and differences between the Chinese and the Caucasian population from the perspectives of epidemiology, clinical, immunology and genetics will help to improve the understanding of LADA, and then promote LADA studies in individual populations.

Relation between the insulin lowering rate and changes in bone mineral density: Analysis among subtypes of type 1 diabetes mellitus

AIMS/INTRODUCTION

Bone mineral density (BMD) in patients with type 1 diabetes mellitus (T1DM) is reduced due to impaired insulin secretion. However, it is unclear whether the rate of BMD reduction is affected by T1DM subtypes. This study aimed to clarify the difference in BMD across T1DM subtypes: slowly progressive (SP), acute-onset (AO), and fulminant (F).

METHODS

This was a retrospective, single-center, cross-sectional study conducted on 98 adult T1DM patients. The main outcome included the BMD Z-score (BMD-Z) measured at the lumbar spine (LS) and femoral neck (FN).

RESULTS

The LS BMD-Z was lower in the AO than in the SP (p =0.03). No differences were observed when compared to the F. The FN BMD-Z tended to be higher in the SP than in the AO and F. Multiple regression analyses showed that the LS BMD-Z was associated with subtypes (AO vs. SP) (p =0.01), but not subtypes (F vs. SP), adjusted for sex, duration, retinopathy, and C-peptide immunoreactivity (CPR). When patients were divided into disease duration tertiles, in the first and second tertiles, the CPR levels were lower in the AO or F than in the SP. In contrast, LS and FN BMD-Z differed between the AO and SP only in the second tertiles (both p <0.01), with a similar tendency between the F and SP.

CONCLUSIONS

Among T1DM subtypes, BMD has time-dependent changes, which reveals that BMD decline follows impaired insulin secretion. These results provide novel insights into the association between the low insulin exposure duration and BMD.

Single-cell RNA sequencing analysis reveals the relationship of bone marrow and osteopenia in STZ-induced type 1 diabetic mice

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scRNA-seq analysis reveals the profiles of bone marrow cells in STZ-induced T1D mice.

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scRNA-seq analysis reveals the heterogeneity of bone marrow immune cells in STZ-induced T1D mice.

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The ratio of BM-neutrophils to B lymphocytes is increased in the bone marrow of STZ-induced T1D mice.

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Osteopenia is occurred in STZ-induced T1D mice.

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This increased ratio is negatively correlated with osteopenia in STZ-induced T1D mice.

Introduction

Type 1 diabetes (T1D) is a multifactorial autoimmune disease. Broad knowledge about the genetics, epidemiology and clinical management of T1D has been achieved, but understandings about the cell varieties in the bone marrow during T1D remain limited.

Objectives

We aimed to present a profile of the bone marrow cells and reveal the relationship of bone marrow and osteopenia in streptozotocin (STZ)-induced T1D mice.

Methods

The whole bone marrow cells from the femurs and tibias of healthy (group C) and STZ-induced T1D mice (group D) were collected for single-cell RNA sequencing analysis. Single-cell flow cytometry and immunohistochemistry were performed to confirm the proportional changes among bone marrow neutrophils (BM-neutrophils) (Cxcr2⁺, Ly6g⁺) and B lymphocytes (Cd19⁺). X-ray and micro-CT were performed to detect bone mineral density. The correlation between the ratio of BM-neutrophils/B lymphocytes and osteopenia in STZ-induced T1D mice was analyzed by nonparametric Spearman correlation analysis.

Results

The bone marrow cells in groups C and D were divided into 12 clusters, and 249 differentially expressed genes were found. The diversity of CD45⁺ immune cells between groups C and D were greatly affected: the proportion of BM-neutrophils showed a significant increase while the proportion of B lymphocytes in group D showed a significant decrease. X-ray and micro-CT analyses confirmed that osteopenia occurred in group D mice. In addition, the results of single-cell flow cytometry and correlation analysis showed that the ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice.

Conclusion

A single-cell RNA sequencing analysis revealed the profile and heterogeneity of bone marrow immune cells in STZ-induced T1D mice for the first time. The ratio of BM-neutrophils/B lymphocytes negatively correlated with osteopenia in STZ-induced T1D mice, which may enhance understanding for treating T1D and preventing T1D-induced osteopenia.

Bone mineral density predictors in long-standing type 1 and type 2 diabetes mellitus

BACKGROUND

Despite the increased fracture risk, bone mineral density (BMD) is variable in type 1 (T1D) and type 2 (T2D) diabetes mellitus. We aimed at comparing independent BMD predictors in T1D, T2D and control subjects, respectively.

METHODS

Cross-sectional case-control study enrolling 30 T1D, 39 T2D and 69 age, sex and body mass index (BMI) - matched controls that underwent clinical examination, dual-energy X-ray absorptiometry (BMD at the lumbar spine and femoral neck) and serum determination of HbA1c and parameters of calcium and phosphate metabolism.

RESULTS

T2D patients had similar BMD compared to T1D individuals (after adjusting for age, BMI and disease duration) and to matched controls, respectively. In multiple regression analysis, diabetes duration - but not HbA1c- negatively predicted femoral neck BMD in T1D (β= -0.39, p = 0.014), while BMI was a positive predictor for lumbar spine (β = 0.46, p = 0.006) and femoral neck BMD (β = 0.44, p = 0.007) in T2D, besides gender influence. Age negatively predicted BMD in controls, but not in patients with diabetes.

CONCLUSIONS

Long-standing diabetes and female gender particularly increase the risk for low bone mass in T1D. An increased body weight partially hinders BMD loss in T2D. The impact of age appears to be surpassed by that of other bone regulating factors in both T1D and T2D patients.

Comparing the bone mineral density among male patients with latent autoimmune diabetes and classical type 1 and type 2 diabetes, and exploring risk factors for osteoporosis

AIMS

This study aimed to compare the bone mineral densities (BMDs) among male patients with latent autoimmune diabetes in adults (LADA), classical type 1 diabetes (T1DM), and type 2 diabetes (T2DM), and to examine the risk factors for developing low BMD in these patients.

PATIENTS AND METHODS

Between January 2017 and October 2020, a total of 57, 67, and 223 male patients with LADA, classical T1DM, and T2DM, respectively, were recruited from the endocrinology department of Shanghai Tenth People's Hospital. Hormonal markers of bone metabolism, lipid profiles, uric acid, glycosylated hemoglobin A1c (HbA1c), and beta-cell function were measured using blood samples. BMD was measured at the lumbar spine, femoral neck, and right hip by dual-energy X-ray absorptiometry.

RESULTS

The mean BMD values from all three skeletal sites in male patients with LADA were comparable to those with classical T1DM but were much lower than those with T2DM. After adjusting for confounding factors, multiple linear regression analysis demonstrated that in all male patients with diabetes, body mass index (BMI), uric acid, and fasting C-peptide showed significant positive associations with BMD at all three skeletal sites; however, osteocalcin showed a negative association at all three sites.

CONCLUSIONS

Compared with male patients with T2DM, lower BMDs were observed in patients with LADA and T1DM. Low BMI, uric acid, C-peptide levels, and high osteocalcin levels are risk factors for developing low BMD in male patients with diabetes.