The optimal vitamin D cut-off value associated with hyperglycemia in an Iranian population

Relationship Between Glycated Hemoglobin (HbA1c) and Vitamin D Levels in Type 2 Diabetes Patients: A Retrospective Cross-Sectional Study

BACKGROUND

Significant links between low serum levels of vitamin D3 and insufficient glycemic control in patients with type 2 diabetes mellitus (T2DM) have been reported previously in the literature. However, there is no exciting evidence on the association between glycated hemoglobin (HbA1c) and vitamin D levels in T2DM individuals in our nation (Yemen). This study aimed to investigate the relationship between HbA1c and vitamin D levels in T2DM patients in a resource-limited setting.

METHOD

A retrospective cross-sectional study was conducted at the Al-Raffa Center, Ibb, Yemen between June 2018 and September 2023 including 396 patients diagnosed with T2DM. The patient characteristics, comorbidities, HbA1c, and vitamin D levels were gathered from patients' medical profiles. Linear regression analysis was used to find the factors associated with vitamin D deficiency (serum 25(OH)D levels < 20 ng/mL) among T2DM patients. Subsequently, the correlation between HbA1c and vitamin D levels was examined using receiver operating characteristic (ROC) curve analysis.

RESULTS

The mean age was 44.6 ±14.6 years and most of them (n= 227, 57.3%) were female and from a rural area (n= 229, 57.8%). Comorbidities were hypertension, dyslipidemia disease, and cardiovascular disease in 176 (44.4%), 63 (15.9%), and 88 (22.2%) cases, respectively. The mean HbA1c was 8.1 ±2.5%. The mean vitamin D level was 26.9 ±16.5 ng/mL and low vitamin D was present in 260 (65.7%) (vitamin D deficiency in 160 (40.4%) and vitamin D insufficiency in 100 (25.3%) cases). In regression analysis, obesity (>30 kg/m2) (odds ratio (OR): 299.49; 95% confidence interval (CI): 72.66 - 1234.42, p <0.0001), higher HbA1c levels (OR: 1.61; 95% CI: 1.26 - 2.05, p =0.0001), and urban residence (OR: 23.98; 95% CI: 5.62 - 102.42, p <0.0001) were associated with vitamin D deficiency. There was a negative correlation between the vitamin D level and HbA1c which was statistically significant (correlation coefficient r: -0.5452; 95% CI: -0.6109 to -0.4720, p <0.0001). Using the ROC analysis, the serum vitamin D value of ≤18.42 ng/ml was the best cut-off point to predict hyperglycemia (area under the curve: 0.633, 95% CI: 0.672 to 0.770, sensitivity: 52%, specificity: 84.71 %, Yoden's index: 0.3671, p <0.001). Based on this cut-off, 39.4% of individuals (37.5% in the normoglycemic group and 90.9% in the hyperglycemic group) were vitamin D deficient.

CONCLUSION

In this study, low vitamin D was common among T2DM patients, especially those with poor glycemic control. We observed a link between HbA1c levels, urban residency, and BMI with vitamin D deficiency in T2DM patients. The association was distinguished by low vitamin D levels and elevated HbA1c. Additionally, we found that the serum vitamin D value of ≤18.42 ng/ml was the best cut-off point to predict hyperglycemia in T2DM patients with moderate agreement. To manage their disease, patients with T2DM should take their medications as prescribed and live a healthy lifestyle. This will increase their overall health, especially their vitamin D levels.

Additive Interaction Between Insulin Resistance, Chronic Low-Grade Inflammation and Vitamin D Deficiency on the Risk of Type 2 Diabetes Mellitus: A Cohort Study

OBJECTIVES

The aim of this study was to explore, on an additive scale, the combined effect of the association between insulin resistance (IR), chronic low-grade inflammation (CLGI) and vitamin D deficiency (VDD) on the risk of type 2 Diabetes Mellitus (T2DM).

METHODS

This is a cohort study, including 1484 non-diabetic subjects, followed for a period of four years. 25 hydroxy-vitamin D (25OHD), hypersensitive C-reactive protein (HsCRP) and triglyceride-glucose index were assessed. Based on VDD and CLGI, the population was subdivided into 4 exposure groups. Analysis was performed both in the case of IR and without IR. Cox proportional regression and additive interaction were applied to explore cumulative effects of exposure.

RESULTS

At follow-up, 162 newly diagnosed cases of T2DM were identified. TYG index (RR = 4.0[2.8-5.6]), HsCRP (RR = 1.6 [1.4-1.7]) and 25OHD (RR = 0.96 [0.39-0.98]) were all significantly associated with the risk of T2DM (p < 0.01). The highest excess risk was recorded in patients cumulating simultaneously IR, CLGI and VDD (RR= 8.4[3.6-19.8], p < 0.0001). The additive interaction was significant, the excess risk linked to the interaction RERI = 10.5[1.43-19.7], the proportion attributable to the combined effect: AP = 0.61[0.37-0.85], and the interaction was synergistic: synergy index: 2.8[1.42-5.69].

CONCLUSION

Baseline levels of TYG index, 25OHD and HsCRP are strongly predictive of future T2DM, and their joint effects are additive and synergistic. Interventional studies are therefore warranted in order to evaluate whether vitamin D supplementation, combined with appropriate anti-inflammatory therapies, is effective as a preventive strategy to reduce the risk of T2DM.

Vitamin D deficiency and hyperglycemia in male rotating shift workers: A disturbed circadian rhythms influence

BACKGROUND

Shift work is related to several negative impacts on the health of workers. This study aimed to evaluate the association between vitamin D deficiency (VDD) and hyperglycemia in shift workers.

METHODOLOGY

This cross-sectional study included male rotating shift workers in an iron ore extraction company. Participants were classified as VDD when 25(OH)D < 20 ng/mL for a healthy population and 25(OH)D < 30 ng/mL for groups at risk for VDD. Hyperglycemia was classified when fasting glucose ≥100 mg/dL or HbA1c ≥ 5.7%. Data were compared using chi-square analysis with Cramer's V as effect size, and Bonferroni correction. Multivariate logistic regression, from a model of determination, was performed to investigate whether VDD was associated with hyperglycemia.

RESULTS

The study evaluated 1411 workers, most workers were aged 30-39 years (53.2%), and 77.5% self-declared as black, brown, with up to complete high school (71.4%) and working alternate shifts for more than 5 years (76.1%). Regarding glucose and vitamin D, 32.0% and 29.1% of the workers had hyperglycemia and VDD, respectively. In multivariate analysis, controlled for confounding factors, workers with VDD had a 119% increased chance of hyperglycemia (OR: 2.19; IC95%: 1.56-3.08). Furthermore, vitamin D levels in distribution quintiles showed a dose-response gradient in relation to hyperglycemia, where increased vitamin D values were associated with a reduction in the occurrence of hyperglycemia.

CONCLUSION

Rotating shift workers with vitamin D deficiency are more likely to have hyperglycemia.

Dietary pattern association with CD4 cells count in patients living with human immunodeficiency virus: A cross-sectional study

Background

Considering contradictory reports about the impact of dietary pattern on CD4 cell count in previous studies and the potential importance of diet on the immune system, this study aimed to assess the association between dietary patterns and CD4 count among HIV-infected patients.

Methods

This cross-sectional study was conducted among HIV-infected patients aged 18-60 who registered in the referral Voluntary Counseling and Testing Center of Shiraz, Iran. The principal component analysis identified nutritional patterns and factors. The association between the score of the dietary patterns and CD4 count was considered in two categories of CD4 more/less than 500 and using backward logistic regression after adjusting for confounders.

Results

A total of 226 participants were included in the analysis. CD4 was significantly lower in males (p < 0.001). Participants with illegal drug use (p < 0.001), HCV (p = 0.001), and HBV (p < 0.001) had lower serum CD4. Four extracted dietary patterns were a Plant-rich diet, Healthy animal-based proteins, a Western diet, and Affordable calorie and protein patterns. There was an association between CD4 and Western diet patterns in the best model in which age, gender, weight, and HBV were included. Each unit increase in Western diet score increased the odds of CD4 less than 500 by 57% (OR = 1.57; CI 95% 1.06-2.34, p = 0.02).

Conclusion

Among the four dietary patterns, the Western diet comprising a high intake of refined sugar and grain, saturated and trans fats, and animal protein sources, especially high-fat red meat, had a statistically significant relationship with a decrease in CD4 cell count.

The relationship between estimated glucose disposal rate and bone turnover markers in type 2 diabetes mellitus

PURPOSE

To investigate the relationship between estimated glucose disposal rate (eGDR) and bone turnover markers in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

This is a cross-sectional study, which recruited 549 patients with T2DM. The eGDRs of patients were calculated based on the presence of hypertension, glycated hemoglobin, and body mass index. All patients were divided into high-eGDR group and low-eGDR group using the median of eGDR as the boundary. The patients were further divided into two subgroups: males and postmenopausal females.

RESULTS

The lower the eGDR, the more severe was insulin resistance. The levels of osteocalcin (OC), type I collagen carboxyl-terminal peptide (β-CTX), and type I procollagen amino-terminal peptide (PINP) were significantly lower in the low-eGDR group than those in the high-eGDR group. The eGDR was positively correlated with OC, β-CTX, and PINP in all patients, and in the male subgroups. In the postmenopausal female subgroup, there was no correlation between eGDR and OC, β-CTX, or PINP. In addition, this positive correlation remained after adjusting for other factors in multilinear regression analysis.

CONCLUSION

Our study was the first to demonstrate that eGDR is positively correlated with bone turnover markers in patients with T2DM. This correlation was observed among the male patients with T2DM but not among postmenopausal female patients with T2DM.

Serum level of Vitamin D is associated with COVID-19 mortality rate in hospitalized patients

BACKGROUND

Due to widespread of coronavirus disease 2019 (COVID-19) infection, identification of its risk factors and clinical characteristics are important. The aim of the present study was to assess Vitamin D levels in individuals with severe acute respiratory syndrome coronavirus-19 infection and to report on its potential as a predictive marker.

MATERIALS AND METHODS

All patients, diagnosed with COVID-19 infection from February 16 to March 21, 2020, and referred to Firoozgar Hospital, Tehran, Iran, were enrolled in this study. Vitamin D analysis was undertaken on patient serum samples using a commercial kit (Pars Azmoon Co., Tehran, Iran). SPSS v. 22 was used for statistical analysis.

RESULTS

Vitamin D serum concentration was analyzed in a total of 317 patients whose mean age ± standard deviation was 62.05 ± 15 years and with 62.5% being male. A significant association of Vitamin D level and death was observed. Higher levels of serum Vitamin D had protection against death (odds ratio = 0.955 [95% confidence interval = 0.923-0.988], P = 0.008).

CONCLUSION

As a preliminary study in the Iranian population who suffered COVID-19 disease, we identified that Vitamin D deficiency was associated with a higher death rate and intensive care unit admission.

The Relationship Between Hemoglobin Glycation Variation Index and Vitamin D in Type 2 Diabetes Mellitus

OBJECTIVE

This study aimed to investigate the relationship between hemoglobin glycation variation index (HGI) and vitamin D in patients with type 2 diabetes mellitus (T2DM).

MATERIALS AND METHODS

This is a cross-sectional study that recruited 347 patients with T2DM. The subjects were divided into no vitamin D deficiency group (25(OH)D ≥20 ng/mL) and vitamin D deficiency group (25(OH)D < 20 ng/mL). HGI was calculated as the difference between the measured and predicted values of HbA1c using the linear relationship between HbA1c level and fasting plasma glucose levels. All study participants were divided into high HGI and low HGI groups using the median of HGI as the boundary. At last, the subjects were divided into male group and female group, and these groups were further subdivided into vitamin D deficiency group and no vitamin D deficiency group.

RESULTS

The levels of HGI were significantly higher in the vitamin D deficiency group compared with the no vitamin D deficiency group for all patients. The same was true for female patients but not for male patients. The prevalence of vitamin D deficiency in the high HGI group was higher than that in the low HGI group. The high HGI group had lower vitamin D levels compared to the low HGI group. Compared to the male group, the female group had lower vitamin D levels but higher HGI levels. A negative correlation existed between 25(OH) D and HGI in all subjects, as well as in the female-only subgroups. In the male-only subgroups, there was no correlation between them, and this positive correlation still existed after adjusting for other factors in multilinear regression analysis.

CONCLUSION

Our study showed for the first time that HGI is inversely associated with vitamin D in all patients with T2DM, and the correlation was also found in female patients, but not in male patients.