Parathyroid hormone is associated with incident diabetes in white, but not black adults: The Atherosclerosis Risk in Communities (ARIC) Study

Association of parathyroid hormone with risk of hypertension and type 2 diabetes: a dose-response meta-analysis

BACKGROUND

Despite an increase in parathyroid hormone (PTH) has been reported to be associated with a higher risk of hypertension and type 2 diabetes (T2D), the comprehensive evaluation of the dose-response relationship between PTH and hypertension and T2D remains ambiguous. Therefore, a dose-response meta-analysis was performed to quantitatively investigate this association.

METHODS

PubMed, Web of Science, and Embase were systematically searched up to May 2023. Random-effect models were used to estimate the summary odds ratios (ORs) and 95% confidence intervals (CIs). Restricted cubic splines were used to model the dose-response association.

RESULTS

Ten articles (including 13 studies) were identified, with a total of 11,878 cases and 51,234 participants in the meta-analysis. Of these studies, eight (five cohort and three cross-sectional) studies investigated the association of PTH with hypertension; five (two cohort and three cross-sectional) studies assessed the association of PTH with T2D. The results showed a positive relationship between PTH and the risk of hypertension (OR,1.24, 95% CI: 1.16-1.33). We found a linear association between PTH and hypertension (Pnon-linearity= 0.222). In the dose-response analysis, the risk of hypertension increased 5% for every 10 pg/ml increase in PTH (OR,1.05, 95% CI: 1.02-1.08). The pooled OR of T2D risk for a 10 pg/ml increase in PTH was 1.00 (95% CI: 0.98-1.02).

CONCLUSIONS

Elevated PTH is associated with an increased risk of hypertension. However, the evidence of the association between PTH and T2D is limited, and more well-designed studies need to be explored.

Association Between Primary Hyperparathyroidism and Secondary Diabetes Mellitus: Findings From a Scoping Review

An ill-defined association exists between diabetes mellitus (insulin resistance) and primary hyperparathyroidism. This article explores this phenomenon while providing an explanation for such a relationship and reviewing the evidence regarding the response to insulin sensitivity following a parathyroidectomy. Primary hyperparathyroidism may increase the risk of developing insulin resistance; peculiarly, this is not present in all patients. It is likely that both intracellular hypercalcemia and hypophosphatemia alter the insulin receptor expression and response; the contribution of parathyroid hormone is less clear. Following parathyroidectomy, patients may demonstrate improvement in their insulin sensitivity, while others have no response or a detrimental effect. A varied phenotype exists among patients, and furthermore, it is unclear why certain patients demonstrate improvement in insulin sensitivity following a parathyroidectomy, whereas others fail to do so. While this review provides a broad overview of the general endocrine community, it is imperative to note that clinical applicability is limited until further studies address these remaining uncertainties. Due to the lack of understanding regarding this endocrinological enigma, the presence of insulin resistance, at this present time, should not be a criterion for a parathyroidectomy.

Vitamin D, parathyroid hormone, glucose metabolism and incident diabetes in the multiethnic study of atherosclerosis

INTRODUCTION

Higher concentrations of serum 25-hydroxyvitamin D (25(OH)D) and lower concentrations of parathyroid hormone (PTH) are associated with lower insulin resistance and incident diabetes in non-Hispanic White and Hispanic Americans. Results are mixed in other populations, with no observational studies in a large multiethnic cohort. The association of serum 25(OH)D with diabetes may vary by adiposity level.

RESEARCH DESIGN AND METHODS

Among 5611 participants in the Multi-Ethnic Study of Atherosclerosis without diabetes at baseline, cross-sectional associations of serum 25(OH)D with homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA-β were examined using linear regressions. The association of 25(OH)D with incident diabetes over 9 years was examined using Cox proportional hazard regression.

RESULTS

Black Americans had the highest proportion of individuals with 25(OH)D<20 ng/mL (61%) and White Americans had the least (17%). Serum 25(OH)D was inversely associated with HOMA-IR in fully adjusted models (-0.34% difference in HOMA-IR per ng/mL higher 25(OH)D, p<0.0001). Longitudinally, a 1 ng/mL higher serum 25(OH)D was associated with 2% lower risk of incident diabetes (HR 0.982, CI 0.974 to 0.991), and a 1 pg/mL higher serum PTH was associated with 1% higher risk of incident diabetes (HR 1.007, CI 1.004 to 1.010), both prior to adjustment for waist circumference. After adjusting for waist circumference, a 1 ng/mL higher 25(OH)D was associated with 1% lower risk of incident diabetes (HR 0.991, CI 0.983 to 1.000). The magnitude of association of serum 25(OH)D with incident diabetes was largest at lower waist circumference (p for interaction=0.025). There was no heterogeneity by race/ethnicity (p=0.317).

CONCLUSIONS

Serum 25(OH)D is inversely associated with insulin resistance and incident diabetes in a diverse cohort, including non-Hispanic White, Black, Hispanic and Chinese Americans. Future research should explore mechanisms for the interaction between serum 25(OH)D and adiposity in this relationship.

Normal parathyroid hormone and non-proliferative diabetic retinopathy in patients with type 2 diabetes

AIMS/INTRODUCTION

To investigate the associations between parathyroid hormone (PTH) and non-proliferative diabetic retinopathy (NPDR) in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

Data were collected from 2,322 patients with type 2 diabetes mellitus in hospital between 2017 and 2019. The odds ratio (OR) and the corresponding 95% confidence interval related to the quartiles of PTH were obtained by logistic regression analysis after adjusting the potential confounding variation.

RESULTS

The patients were stratified into quartiles (Q1-Q4) based on the PTH levels, with the cut-off limits of ≤23.74, 23.74-29.47, 29.47-37.30 and >37.30 pg/mL in men, and ≤24.47, 24.47-31.22, 31.22-39.49 and >39.49 pg/mL in women. The first quartile (Q1) represents the lowest quartile and the fourth quartile (Q4) is the highest. According to the quartiles (Q1-Q4), the prevalence rate of NPDR in patients showed a significantly decreasing trend (37.9%, 36.3%, 34.0% vs 24.0% in men; 43.2%, 40.5%, 31.1% vs 26.2% in women, both P < 0.05). Independent of age, diabetes duration and other metabolic factors, multivariate logistic regression showed that participants in Q4 had a lower OR of NPDR than those in Q1 (OR 0.443, 95% confidence interval 0.300-0.654, P < 0.001 for men; OR 0.428, 95% confidence interval 0.283-0.646, P < 0.001 for women).

CONCLUSIONS

Low serum PTH levels were significantly associated with complications of NPDR in inpatients. Its causality remains to be further studied.

Is 25-Hydroxyvitamin D Associated with Glycosylated Hemoglobin in Patients with Type 2 Diabetes Mellitus in Saudi Arabia? A Population Based Study

BACKGROUND

Saudi Arabia has a high burden of diabetes mellitus and vitamin D deficiency. The objective of this study was to explore the association between glycosylated hemoglobin and 25-hydroxyvitamin D in patients with type 2 diabetes mellitus (T2DM) in Riyadh, Saudi Arabia.

METHODS

An interview based cross-sectional study was conducted on 606 patients with type 2 diabetes, aged 30-75 years, visiting primary health care centers. Blood samples were collected for measuring HbA1c, 25(OH)D and bone and lipid markers. Multivariable linear regression analysis was conducted to explore the association between HbA1c and 25(OH)D.

RESULTS

The mean (±SD) levels for HbA1c and 25(OH) D were 7.69 (±1.77) and 44.28 (±23.06), respectively. Around 55% of patients had uncontrolled HbA1c (>7.0), whereas vitamin D deficiency (<50 nmol/L) was found in 52.3% (=317). Multiple linear regression analysis found that a unit increase in vitamin D levels and parathyroid hormone levels was associated with -0.17 (-0.02, -0.01, p < 0.001) and -0.20 (-2.66, -1.18, p < 0.001) unit decrease in levels of HbA1c, respectively. Similarly, increasing age was associated with -0.15 (-0.01, -0.04, p = 0.002) unit decrease in HbA1c levels, whereas unit increases in serum alkaline phosphatase, calcium and diabetes duration were associated with 0.22 (0.01, 0.02, p < 0.001), 0.14 (1.03, 3.88, p = 0.001) and 0.26 (0.42, 0.78, p < 0.001) unit increase in HbA1c levels, respectively.

CONCLUSION

HbA1c levels are associated with 25-hydroxyvitamin D levels. For better control of HbA1c levels, it is important to maintain 25-hydroxyvitamin D level and bone markers within normal range.

Associations between Osteocalcin, Calciotropic Hormones, and Energy Metabolism in a Cohort of Chinese Postmenopausal Women: Peking Vertebral Fracture Study

OBJECTIVE

The endocrine function of bone in energy metabolism may be mediated by the osteocalcin (OC). We examined the association between OC and energy metabolism among Chinese postmenopausal women. Design and Setting. A cross-sectional cohort study enrolling 1635 participants was conducted using data from the Peking Vertebral Fracture study. Partial correlation analysis was performed to explore the correlation of OC, parathyroid hormone (PTH), or 25-hydroxyvitamin D (25(OH)D) with glycemic and lipid metabolic parameters. A logistic regression model was used to investigate the association of OC, PTH, or 25(OH)D with the prevalence of diabetes and dyslipidemia.

RESULTS

Serum levels of OC, PTH, and 25(OH)D were all positively correlated with serum cholesterol levels, whereas only OC was negatively associated with serum glucose level. In the logistic regression model, both OC and PTH were negatively associated with the prevalence of diabetes (odds ratio [OR], 95% confidence interval [95% CI]: 0.967, 0.948-0.986 for OC and 0.986, 0.978-0.994 for PTH). No significant association was found between 25(OH)D and diabetes. Both OC and 25(OH)D, rather than PTH, were associated with abnormalities of high cholesterol levels, such as hypercholesterolemia and high LDL-C levels. Further classifying the population based on the median value of OC and PTH, low OC and low PTH subgroup had the highest OR, 95% CI for diabetes (1.873, 1.287-2.737) and the lowest OR, 95% CI for hypercholesterolemia (0.472, 0.324-0.688) and for high LDL-C (0.538, 0.376-0.771).

CONCLUSION

Among Chinese postmenopausal women, a lower serum level of OC was associated with a higher prevalence of diabetes and lower serum cholesterol levels, and a low PTH concentration could magnify these associations.

Racial Differences in Dietary Relations to Cognitive Decline and Alzheimer's Disease Risk: Do We Know Enough?

The elderly population in the US is increasing and projected to be 44% minority by 2060. African Americans and Hispanics are at increased risk of cognitive impairment and Alzheimer’s disease compared to non-Hispanic whites. These conditions are associated with many other adverse health outcomes, lower quality of life, and substantial economic burden. In the past few decades, diet has been identified as an important modifiable risk factor for cognitive decline and Alzheimer’s disease. Some studies report poor diet quality among African American and Hispanic older adult populations compared to their white counterparts. We have a limited understanding of how diet affects brain health in different racial-ethnic groups. One primary reason for our lack of knowledge is that most cohort studies are of majority non-Hispanic white participants. Moreover, those that do include minority participants do not publish their findings stratified by racial-ethnic groups, and likely have a less accurate measurement of dietary intake among minority groups. In this review, we summarize the current, albeit limited, literature on racial/ethnic differences in dietary relations to dementia outcomes. We will also discuss methodological issues in conducting nutrition studies in diverse cultures, and suggestions for future research directions. Overcoming the gaps will make it possible to make dietary recommendations for Alzheimer’s prevention that are more relevant for different racial/ethnic groups and set us on a faster track to reduce health disparities.

Circulating calcium levels and the risk of type 2 diabetes: a systematic review and meta-analysis

Abnormal Ca homeostasis has been associated with impaired glucose metabolism. However, the epidemiological evidence is controversial. We aimed to assess the association between circulating Ca levels and the risk of type 2 diabetes mellitus (T2DM) or abnormal glucose homeostasis through conducting a systematic review and meta-analysis. Eligible studies were identified by searching electronic database (PubMed, Embase and Google Scholar) and related references with de novo results from primary studies up to December 2018. A random-effects meta-analysis was performed to estimate the weighted relative risks (RR) and 95 % CI for the associations. The search yielded twenty eligible publications with eight cohort studies identified for the meta-analysis, which included a total of 89 165 participants. Comparing the highest with the lowest category of albumin-adjusted serum Ca, the pooled RR was 1·14 (95 % CI 1·05, 1·24) for T2DM (n 51 489). Similarly, serum total Ca was associated with incident T2DM (RR 1·25; 95 % CI 1·10, 1·42) (n 64 502). Additionally, the adjusted RR for 1 mg/dl increments in albumin-adjusted serum Ca or serum total Ca levels was 1·16 (95 % CI 1·07, 1·27) and 1·19 (95 % CI 1·11, 1·28), respectively. The observed associations remained with the inclusion of a cohort study with ionised Ca as the exposure. However, data pooled from neither case-control (n 4) nor cross-sectional (n 8) studies manifested a significant correlation between circulating Ca and glucose homeostasis. In conclusion, accumulated data from the cohort studies suggest that higher circulating Ca levels are associated with an augmented risk of T2DM.

Derangement of calcium metabolism in diabetes mellitus: negative outcome from the synergy between impaired bone turnover and intestinal calcium absorption

Both types 1 and 2 diabetes mellitus (T1DM and T2DM) are associated with profound deterioration of calcium and bone metabolism, partly from impaired intestinal calcium absorption, leading to a reduction in calcium uptake into the body. T1DM is associated with low bone mineral density (BMD) and osteoporosis, whereas the skeletal changes in T2DM are variable, ranging from normal to increased and to decreased BMD. However, both types of DM eventually compromise bone quality through production of advanced glycation end products and misalignment of collagen fibrils (so-called matrix failure), thereby culminating in a reduction of bone strength. The underlying cellular mechanisms (cellular failure) are related to suppression of osteoblast-induced bone formation and bone calcium accretion, as well as to enhancement of osteoclast-induced bone resorption. Several other T2DM-related pathophysiological changes, e.g., osteoblast insulin resistance, impaired productions of osteogenic growth factors (particularly insulin-like growth factor 1 and bone morphogenetic proteins), overproduction of pro-inflammatory cytokines, hyperglycemia, and dyslipidemia, also aggravate diabetic osteopathy. In the kidney, DM and the resultant hyperglycemia lead to calciuresis and hypercalciuria in both humans and rodents. Furthermore, DM causes deranged functions of endocrine factors related to mineral metabolism, e.g., parathyroid hormone, 1,25-dihydroxyvitamin D3, and fibroblast growth factor-23. Despite the wealth of information regarding impaired bone remodeling in DM, the long-lasting effects of DM on calcium metabolism in young growing individuals, pregnant women, and neonates born to women with gestational DM have received scant attention, and their underlying mechanisms are almost unknown and worth exploring.