Association of vitamin D and vitamin B12 deficiencies with metabolic and hepatic parameters in patients with type 2 diabetes mellitus

Abstract

Micronutrients have become one of the potentially adjustable determinants of the pathophysiology and complications of T2DM. Of them, vitamin D and B12 have been particularly highlighted. Objectives: to estimate the prevalence of both vitamin D and B12 deficiencies in parallel association with T2DM patients and their relationships with major metabolic and hepatic parameters. This study adopted a cross-sectional analytical design performed in a healthcare center located in the district of Ramallah in Palestine. In total, 295 patients fulfilled these criteria and were included in this final analysis. The present study underlines the high prevalence of vitamin D deficiency and the relatively lower, but clinically relevant, incidence of vitamin B12 deficiency in patients affected by type 2 diabetes mellitus within the adult population of the Ramallah district in Palestine. It also demonstrated that low levels of vitamin D were strongly associated with important metabolic and cardiovascular risk factors.

Keywords

vitamins D deficiency B12 deficiency T2DM patients metabolic hepatic parameters cardiovascular

Introduction

Micronutrients have become one of the potentially adjustable determinants of the pathophysiology and complications of T2DM. Of them, vitamin D and B12 have been particularly highlighted. Vitamin D is a fat soluble secosteriod commonly recognised as the protein in calcium and bone metabolism.¹ Nevertheless, vitamin D receptors can be found in pancreatic b-cells, adipocytes, and immunocytes implying expanded outcomes on insulin sensitivity, inflammation, and glucose homeostasis.² There is insulin resistance, alterations in b-cell functions, and the probability of developing T2DM that is linked to low serum 25-hydroxyvitamin D levels.³

Vitamin B12 (cobalamin) is a soluble micronutrient mandatory in the blood red cell formation, the burden of the nervous system, and the production of DNA.⁴ Notably, metformin, which is a common first-line treatment used in the management of T2DM, has been consistently associated with vitamin B12 malabsorption, which creates an increased risk of deficient individuals religiously in diabetic people as opposed to diabetic controls.⁴ The long-term and high dosages of metformin medication augment the risk.⁵

Vitamin D deficiency has been linked clinically to poor metabolic effects, such as glycaemic, dyslipidaemia, and renal effects.^6,7 Besides, vitamin D has a renoprotective effect as it acts to regulate the activity of the renin-angiotensin system and to alleviate oxidative stress.⁸

B12 deficiency on the other hand is associated with a number of hepatorenal and metabolic dysfunctions. B12 deficiency is a contributor of peripheral neuropathy in patients with diabetes and can increase the neurological consequences of diabetes.⁹ It is however also linked to high levels of homocysteine, dysfunction of endothelial as well as oxidative stress, which are involved in cardiovascular and renal complications.¹⁰ There is evidence that lower vitamin B12 concentrations can change activity of liver enzymes and hepatic impairment and anaemia and cognitive dysfunction are well-known outcomes of chronic vitamin B12 deficiency.¹¹

This study is thus geared towards bridging these gaps. Through the study on both vitamin D and B12 deficiencies in parallel association with T2DM patients, it aims to explain the prevalence of both and their relationships with major metabolic and hepatic parameters.

Methods and materials

Study design and setting

This study adopted a cross-sectional analytical design and was performed in a healthcare center located in the district of Ramallah in Palestine. The duration of the study was from February 2024 to March 2025.

Inclusion and exclusion criteria

Patients of both genders aged 18 years and above, with a confirmed diagnosis of Type 2 diabetes mellitus, were considered eligible for inclusion. Of the eligible patients, only those who underwent routine follow-up visits and had complete clinical and laboratory records were included in this study. Exclusion criteria included known chronic liver disease, end-stage renal disease (eGFR < 15 mL/min/1.73m²), malignancy, pregnancy, and supplement intake of vitamin D or B12 within 6 months. In total, 295 patients fulfilled these criteria and were included in this final analysis.

Data collection and laboratory measures

Patient demographic information and clinical history were obtained from medical records. The laboratory data were extracted from the centre’s diagnostic laboratory system. Vitamin D was measured as serum 25-hydroxyvitamin D [25(OH)D] by a chemiluminescent immunoassay, with deficiency defined as <50 nmol/L. Electrochemiluminescence was used to measure Vitamin B12 status, and <147.6 pmol/L was used to define deficiency. Glycemic control was determined by evaluating HbA1c (%) and fasting blood sugar (µmol/L). Lipid parameters measured involved total cholesterol, triglycerides, HDL-C, and LDL-C. Hepatic function was evaluated by serum ALT and AST levels (IU/L).

Statistical analysis

Data analysis was performed using IBM SPSS Statistics, Version 26. Binary logistic regression was carried out to determine factors independently associated with vitamin D and B12 deficiencies, and statistical significance was set at a p-value less than 0.05.

Results

Clinical characteristics of diabetic patients

Table 1 outlines the clinical characteristics of the diabetic patients enrolled in the study (n = 295). The average systolic and diastolic blood pressures were 130.4 ± 17.34 mmHg and 77.1 ± 12.47 mmHg, respectively. The mean HbA1c was 8.82%. The majority of patients were receiving biguanides (95%), followed by sulfonylureas (60.3%) and dipeptidyl peptidase inhibitors (41.6%). (Supplemental Table S1 and Table S2).

Table 1.

Logistic regression analysis for factors associated with vitamin D and vitamin B12 deficiencies.

Clinical parameters	Vitamin D deficiency (<50 nmol/L) OR	95% CI	P-value	Vitamin B12 deficiency (<147.6 pmol/L) OR	95% CI	P-value
SBP (mmHg)	1.004	0.976–1.033	0.775	1.052	1.016–1.090	0.004*
DBP (mmHg)	1.068	1.023–1.116	0.003*	1.009	0.960–1.062	0.717
HbA1c (%)	1.723	1.114–2.666	0.015*	0.942	0.641–1.384	0.762
B.S (µmol/L)	1.016	1.000–1.032	0.052	1.001	0.990–1.011	0.911
Creatinine Serum (mg/dL)	6.126	0.999–37.547	0.050	2.950	0.351–24.764	0.319
BUN (mg/dL)	1.021	0.950–1.098	0.569	1.041	0.954–1.135	0.367
TC (mmol/L)	1.014	1.004–1.025	0.009*	1.008	0.993–1.024	0.291
TG (mmol/L)	1.005	1.000–1.010	0.057	1.003	1.001–1.006	0.008*
HDL-C (mmol/L)	0.999	0.953–1.047	0.964	0.760	0.660–0.875	<0.001*
LDL-C (mmol/L)	1.020	1.004–1.036	0.015*	1.009	0.994–1.024	0.252
Vitamin B12 (mmol/L)	0.997	0.995–0.998	<0.001*	—	—	—
Vitamin D (mmol/L)	—	—	—	0.835	0.763–0.913	<0.001*
ALT (IU/L)	1.055	1.006–1.108	0.029*	1.075	1.039–1.111	<0.001*
AST (IU/L)	1.024	0.964–1.088	0.440	1.077	1.008–1.151	0.029*
Biguanide use (ref. No)
Yes	1.005	0.512-3.44	0.99	1.37	0.92-1.108	0.056

*P-values less than 0.05 interpreted statistically significant

Clinical predictors of vitamin D deficiency among diabetic patients

Of the total patients, 94.2% (n = 278) of patients were classified as having vitamin D deficiency. Univariate Logistic regression analysis identified several clinical parameters that were significantly associated with vitamin D deficiency, including diastolic blood pressure (OR: 1.068, 95% CI: 1.023–1.116, p = 0.003), HbA1c (OR: 1.723, 95% CI: 1.114–2.666, p = 0.015), total cholesterol (OR: 1.014, 95% CI: 1.004–1.025, p = 0.009), LDL-C (OR: 1.020, 95% CI: 1.004–1.036, p = 0.015), vitamin B12 (OR: 0.997, 95% CI: 0.995–0.998, p < 0.001), and ALT (OR: 1.055, 95% CI: 1.006–1.108, p = 0.029) (Tabl1).

Clinical predictors of B12 deficiency among diabetic patients

Among the total number of patients, 3.4% (n = 10) were found to have vitamin B12 deficiency. Univariate Logistic regression analysis identified multiple variables significantly associated with vitamin B12 deficiency, including systolic blood pressure (OR: 1.052, 95% CI: 1.016–1.090, p = 0.004), triglycerides (OR: 1.003, 95% CI: 1.001–1.006, p = 0.008), HDL-C (OR: 0.760, 95% CI: 0.660–0.875, p < 0.001), vitamin D (OR: 0.835, 95% CI: 0.763–0.913, p < 0.001), ALT (OR: 1.075, 95% CI: 1.039–1.111, p < 0.001), and AST (OR: 1.077, 95% CI: 1.008–1.151, p = 0.029). Metformin (biguanide) use was not significantly associated with vitamin B12 deficiency in this study. Patients receiving biguanides showed an odds ratio of 1.37 (95% CI: 0.92–1.108, p = 0.056), indicating a borderline but non-significant relationship. Similarly, no association was observed with vitamin D deficiency (OR: 1.005, 95% CI: 0.512–3.44, p = 0.99) (Table 1).

Discussion

International cohort studies have reported elevated DBP as a predictor of vitamin D deficiency, depicting an inverse association between vitamin D status and vascular health. Our cross-sectional analysis revealed that serum levels of 25(OH)D were inversely associated with blood pressure, consistent with the results of previous meta-analyses of observational studies.^12,13 Jiang et al. (2024) identified, in their population-based analysis, that lower levels of vitamin D were associated with higher levels of systolic and diastolic blood pressure, together with a higher risk of hypertension. This may be related to the effect of vitamin D on maintaining vascular health and regulating the renin-angiotensin system.¹⁴

Poor blood sugar control, higher HbA1c, is a strong indicator of vitamin D insufficiency. This finding agrees with previous reports that individuals with vitamin D deficiency frequently show high levels of HbA1c.¹⁵ The current study found that vitamin D deficiency is widely associated with a poor lipid profile, represented by high TC and LDL-C.^16,17 The positive correlation of ALT with vitamin D deficiency suggests metabolic stress and hepatic involvement.¹⁸

In this study, triglycerides had a positive association with vitamin B12 deficiency.^19,20 Results from this study indicated that high HDL-C reduces the risk of B12 deficiency.²¹ A further finding from the current study indicated that ALT and AST levels were also related to B12 deficiency.^22,23

This study has great clinical implications on the management of diabetes, particularly in areas where vitamin D and B12 deficiencies are very high. Considering the fact that vitamin D deficit is highly prevalent in this diabetic cohort, the practice of screening vitamin D and B12 deficit should be included in the list of diabetic care practices.¹ Besides, patients with metformin in their treatment could be more prone to vitamin B12 deficiency, and regular B12 analysis is required as suggested by several clinical guidelines.^2,24

Future studies on the causality effect of vitamin D and B12 deficiencies and complication development of diabetes should apply longitudinal research, and intervention trials are required in order to conclude whether metabolic control and hepatorenal outcomes can be tangibly improved by the methods of correcting these deficiencies.

Conclusion

The present study underlines the high prevalence of vitamin D deficiency and the relatively lower, but clinically relevant, incidence of vitamin B12 deficiency in patients affected by type 2 diabetes mellitus within the adult population of the Ramallah district in Palestine. It also demonstrated that low levels of vitamin D were strongly associated with important metabolic and cardiovascular risk factors.

Supplemental material

Supplemental material - Association of vitamin D and vitamin B12 deficiencies with metabolic and hepatic parameters in patients with type 2 diabetes mellitus

Supplemental material for Supplemental material - Association of vitamin D and vitamin B12 deficiencies with metabolic and hepatic parameters in patients with type 2 diabetes mellitus by Ammar A. Jairoun, Moyad Shahwan, Sabaa S. Al-Hemyari, Naseem Abdulla, Abdul Haq Suliman, Ghala Rashid Alnuaimi, Wala Ibrahim Elsheikh and Ammar Ali Saleh Jaber in Diabetes & Vascular Disease Research

Footnotes

ORCID iDs

Ammar A. Jairoun

Moyad Shahwan

Sabaa S. Al-Hemyari

AbdulHaq Suliman

Ammar Ali Saleh Jaber

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by the Ajman University (2025-IRG-COD-9).

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Supplemental material

Supplemental material for this article is available online.

References

Sayedali

Yalin

. Association between metformin and vitamin B12 deficiency in patients with type 2 diabetes. World journal of diabetes 2023; 14(5): 585–593. https://doi.org/10.4239/wjd.v14.i5.585

Infante

Leoni

Caprio

, et al. Long-term metformin therapy and vitamin B12 deficiency: an association to bear in mind. World journal of diabetes 2021; 12(7): 916–931. https://doi.org/10.4239/wjd.v12.i7.916

Zittermann

Trummer

Theiler-Schwetz

, et al. Vitamin D and cardiovascular disease: an updated narrative review. International journal of molecular sciences 2021; 22(6): 2896. https://doi.org/10.3390/ijms22062896

Cortese

Costantino

Luzi

, et al. Vitamin D and cardiovascular disease risk. A literature overview. Molecular Biology Reports 2022; 49(9): 8925–8942. https://doi.org/10.1007/s11033-022-07373-6

Atia

Abdelzaher

Nassar

, et al. Investigating the relationship between vitamin-D deficiency and glycemia status and lipid profile in nondiabetics and prediabetics in Saudi population. Medicine 2023; 102(47): e36322. https://doi.org/10.1097/MD.0000000000036322

Loh

Azizan

Sukor

. Connecting the dots: renin-angiotensin-aldosterone system, vitamin D, and hypertension. Journal of Hypertension 2025; 43(7): 1136–1145. https://doi.org/10.1097/HJH.0000000000004046

Didangelos

Karlafti

Kotzakioulafi

, et al. Vitamin B12 supplementation in diabetic neuropathy: a 1-year, randomized, double-blind, placebo-controlled trial. Nutrients 2021; 13(2): 395. https://doi.org/10.3390/nu13020395

Boachie

Adaikalakoteswari

Samavat

, et al. Low Vitamin B12 and Lipid Metabolism: Evidence from Pre-Clinical and Clinical Studies. Nutrients 2020; 12(7): 1925. https://doi.org/10.3390/nu12071925

Abukhalil

Falana

Hamayel

, et al. Vitamin D Deficiency Association with Comorbid Diseases in Palestine:“A Cross-Sectional Observation Study”. International Journal of General Medicine 2022; 15: 8033–8042. https://doi.org/10.2147/IJGM.S389190

10.

Zhang

Cheng

Wang

, et al. Effect of vitamin D on blood pressure and hypertension in the general population: An update meta-analysis of cohort studies and randomized controlled trials. Prev. Chronic Dis 2020; 17: E03. https://doi.org/10.5888/pcd17.190307

11.

Mokhtari

Hajhashemy

Saneei

. Serum vitamin D levels in relation to hypertension and pre-hypertension in adults: A systematic review and dose-response meta-analysis of epidemiologic studies. Systematic Review. Front. Nutr 2022; 9: 829307. https://doi.org/10.3389/fnut.2022.829307

12.

Zhao

Zhen

Wang

, et al. The relationship between vitamin D deficiency and glycated hemoglobin levels in patients with type 2 diabetes mellitus. Diabetes, Metabolic Syndrome and Obesity 2020; 21: 3899–3907. https://doi.org/10.2147/DMSO.S275673

13.

Kostoglou-Athanassiou

Athanassiou

Gkountouvas

, et al. Vitamin D and glycemic control in diabetes mellitus type 2. Ther Adv Endocrinol Metab 2013; 4(4): 122–128. https://doi.org/10.1177/2042018813501189

14.

Jafari

Fallah

Barani

. Effects of vitamin D on serum lipid profile in patients with type 2 diabetes: a metaanalysis of randomized controlled trials. Clinical nutrition 2016; 35(6): 1259–1268. https://doi.org/10.1016/j.clnu.2016.03.001

15.

Shenoy

Datta

Prabhu

, et al. Association between vitamin D, fasting blood glucose, HbA1c and fasting lipid profile in euglycemic individuals. J Res Diabetes 2014; 2014: a1–a8. https://doi.org/10.5171/2014.929743

16.

Konuksever

Karakaya

. Evaluation of correlation between vitamin D with vitamin B12 and folate in children. Nutrition 2022; 99: 111683.

17.

Devi

. Vitamin B12 Status and Its Impact on Cardiovascular Risk Factors: Insights from A Hospital Based Cross-Sectional Study. Int J Acad Med Pharm 2023; 5(5): 1160–1164.

18.

Adaikalakoteswari

Jayashri

Sukumar

, et al. Vitamin B12 deficiency is associated with adverse lipid profile in Europeans and Indians with type 2 diabetes. Cardiovascular diabetology 2014; 13(1): 129. https://doi.org/10.1186/s12933-014-0129-4

19.

Wasilewska

Narkiewicz

Rutkowski

, et al.

Is there any relationship between lipids and vitamin B levels in persons with elevated risk of atherosclerosis?

Med Sci Monit 2003; 9(3): CR147–CR151.

20.

Yajnik

Deshpande

Jackson

, et al. Vitamin B12 and folate concentrations during pregnancy and insulin resistance in the offspring: the Pune Maternal Nutrition Study. Diabetologia 2008; 51(1): 29–38. https://doi.org/10.1007/s00125-007-0793-y

21.

Zhang

Cui

, et al. Combined effects of vitamin D deficiency and systemic inflammation on all-cause mortality and cause-specific mortality in older adults. BMC Geriatrics 2024; 24(1): 122. https://doi.org/10.1186/s12877-024-04706-x

22.

Zhu

Liao

, et al. Associations of serum folate and vitamin B12 levels with all-cause mortality among patients with metabolic dysfunction associated steatotic liver disease: a prospective cohort study. Frontiers in Endocrinology [Internet] 2024; 15: 1426103. https://doi.org/10.3389/fendo.2024.1426103

23.

Mays

. Increasing Vitamin B12 Screening Among Patients With Type 2 Diabetes on Long-Term Metformin Therapy. Clinical Diabetes 2021; 39(4):424–426. https://doi.org/10.2337/cd20-0108

24.

Temova Rakuša

Roškar

Hickey

, et al. Vitamin B12 in Foods, Food Supplements, and Medicines—A Review of Its Role and Properties with a Focus on Its Stability. Molecules [Internet] 2022; 28(1): 240. https://doi.org/10.3390/molecules28010240