INTRODUCTION:

Diabetes mellitus is one of the 5th leading causes of death and it is a chronic non-communicable disease. The global prevalence of diabetes reached 463 million in 2019, and it is expected to rise to 548 million by 2045^1,2. Type 2 diabetes is currently more prevalent in both urban and rural India³.

Type 2 diabetes mellitus comprises almost 90% of all diabetes cases. In people with diabetes, chronic hyperglycemia can lead to long-term damage, malfunction, or failure of different organs, including the eyes, kidneys, nerves, heart, and arteries^4,5.

Even though the treatment of diabetes has improved in recent decades, it remains necessary to develop new insights for the prevention and management of type 2 diabetes due to the increasing prevalence of this disease.

In current practice, the available treatment is very expensive for patients and their families, and this burden is growing rapidly^6,7.

Dihydroxycholecalciferol, or calcitriol, is a form of vitamin D3 that is active⁸. It is an important nutrient and well known for its classical actions for the normal growth and development of strong bones⁹. The majority of studies report an 80%-90% prevalence of vitamin D deficiency in India. It is important to raise awareness for the public and healthcare providers of the importance of Vitamin D and the consequences of its deficiency. Recently, a low level of vitamin D is being correlated to the development of diabetes, which can cause insulin resistance, beta-cell death, and inflammation which are crucial factors in the development of diabetes. Vitamin D supplementation can reduce inflammation and insulin resistance^10-12.

T2DM patients had a considerably lower circulating concentration of 25 (OH) D than healthy controls¹³. Vitamin D is being proposed to improve insulin resistance by upregulating the insulin receptor, affecting calcium and phosphorus metabolism for type two diabetes¹⁴. One of the studies showed that vitamin D supplementation enhances insulin secretion and its action¹⁵. Also, the study of 126 healthy persons found a direct link between insulin sensitivity and 25(OH)D levels, and a negative effect of vitamin D deficiency on pancreatic-cell activity¹⁶.

Teneligliptin is the drug that belongs to dipeptidyl peptidase 4 inhibitors¹⁷. And metformin is the 1^st choice of a drug belonging to a biguanide group both are used as antidiabetic drugs^18-20Metformin lowers hepatic glucose synthesis and intestinal glucose absorption. It also enhances peripheral glucose uptake and its utilization and improves insulin sensitivity²¹.

Correctional studies have shown that vitamin D is negatively correlated with HbA1c²². While Randhawa FA, et al, showed no correlation between HbA1c and vitamin D in their study²³. Considering these findings, we can hypothesize that Vitamin D supplements can reduce HbA1c levels in diabetics. In view of the inconsistent evidence, we conducted this study for our population to evaluate the effect of vitamin D on blood glucose in type 2 diabetes mellitus. Furthermore, the findings of our study could provide useful information regarding Vitamin D supplementation as well as the management of type 2 diabetes and may open up new discussion forums.

MATERIALS AND METHODS:

A prospective interventional, parallel, randomized study, was conducted on 112 type two diabetes and 25(OH) D deficient patients recruited from the OPD of General Medicine at Mayo Institute of Medical Sciences Barabanki, Lucknow, India. The study protocol was approved by the Ethics Committee of the institute (MIMS/EX/2020/63) before the recruitment of subjects informed consent was obtained from the subjects. Patients with type 2 diabetes mellitus of either sex aged 30-75 years, with vitamin D deficiency, and those willing to participate in the study were enrolled. And patients with type 1 diabetes mellitus and liver diseases, kidney diseases, and lactating or pregnant women were excluded from this study.

Demographic characteristics including weight and height, BMI anddiabetes mellitus history, and the duration of the disease, were recorded

After screening for vitamin D, patients were randomly divided into two groups to a 1:1 ratio, using Computer Allocation software (version 2.0). The control group received Metformin (500mg BD) and Teneligliptin (20 mg OD) only, while the intervention group was given Metformin plus Teneligliptin along with vitamin D (Cholecalciferol) (Uprise – D3) (60,000 IU).

Vitamin D (Cholecalciferol) was given every week for 2 months and then every month for the next four-month.
Subjects were asked not to change antidiabetic drugs during the study period. In addition, patients were instructed not to discard the empty strips and to return them at the end of the month. This was to ensure that compliance could be physically confirmed. Every month for the sixth month, follow-up visits were made. biochemical parameters such as HbA1c levels were measured at baseline, three months, and then six months, fasting plasma glucose (FPG), and postprandial plasma glucose (PPG) were estimated every month for 6 months, SGPT and SGOT, creatine, and blood urea nitrogen were measured at the baseline and then at the end of six months. All the data were analyzed by using Jamovi 2.3 An independent t-test was used to compare study parameters in intervention and control groups at the end of the third and sixth months of the study. And the p-value <0.05 was considered significant.

RESULT:

A total of (n = 214) participants were included of which 112 patients were randomized into an interventional group (n = 56) and (n = 56) into control group. A total of nine patients in the interventional group and eleven patients in the control group did not turn up for the follow-up at the end of 3 to 6 months of the study (Fig 1).

The mean age of the participants was 52.17±7.70 years in the interventional group while 53.35±9.29 years in the control group. and Among the interventional and control groups, respective BMI was 23.62±3.02kg/m² and 24.41±2.93kg/m²other baseline findings are given in (Table 1).

At the end of 3^rd month, a significant improvement in serum 25-hydroxyvitamin D levels was noted in the interventional group where it was 30.97±5.02 ng/ml (p = <.001). At the end of 3^rd of month follow-up, there was a significant difference in mean FPG and PPG (129.86±7.36mg/dl) vs. (136.12±11.31mg/dl) (p =0.002), (220.81±13.04mg/dl) vs. (228.06±19.40mg/dl) (p = 0.037). in the interventional and control group respectively. And subsequently, mean HbA1c improved significantly in the interventional group as compared to the control group 7.21±0.40% vs. 7.48.0.62% respectively (p = 0.015). other variables are given in (Table 2).

As expected, mean 25-hydroxyvitamin D levels increased significantly as compared to the control group (p = < .001) and the measures of glycemic control (FPG, PPG, HbA1c) showed a significant improvement at the end of the 6 months. Additionally, slight but significant improvement was noted in blood urea nitrogen (BUN) in the interventional group, over the period of 6 months (p = 0.049). That indicates vitamin D can improve Kindy’s function. But no significant change was noted in SGPT, SGOT, and serum creatinine after vitamin D supplementation in the interventional group at the end of 6 months of the study (Table 3).

Figure 1: Flow chart of the patient

Table 1 Demographic characteristics and biochemical variables (n= 92)

Variables	Intervention group (n = 47)	Control group (n = 45)
Duration of Type 2 DM	3.29±1.31	3.08±1.18
Age (yrs.)	52.10±7.62	53.35±9.29
Gender Male Female	27 20	25 20
Vitamin D (ng/ml)	14.01±2.63	13.80±2.64
BMI (kg/m2)	23.75±3.03	24.41±2.93
FPG (mg/dl)	150.18±10.25	151.46±10.33
PPG (mg/dl)	248.95±11.59	249.43±11.45
HbA1c (%)	7.99±0.37	8.06±0.32
SGPT (IU/l)	30.51±2.30	29.69±2.30
SGOT (IU/l)	33.49±5.08	32.49±4.49
S cr.(mg/dl)	0.91±014	0.89±0.14
BUN(mg/dl)	10.71±1.79	10.31±1.17

Abbreviation:

BMI(Body mass index), FPG (Fasting plasma glucose), PPG (Postprandial glucose), HbA1c (glycated hemoglobin), SGPT (serum glutamic pyruvic transaminase), SGOT (Serum glutamic oxaloacetic transaminase), S cr. (Serum creatinine), BUN (Blood urea nitrogen)

Table 2 characteristics at the end of 3 month

Variables	Intervention group (n = 47)	Control group (n = 45)	P value
Vitamin D (ng/ml)	30.97±5.02	13.75±2.30	< .001*
BMI (kg/m2)	23.87±2.95	23±3.71	0.482
FPG (mg/dl)	129.86±7.36	136.12±11.31	0.002*
PPG (mg/dl)	220.81±13.04	228.06±19.40	0.037*
HbA1c (%)	7.21±0.40	7.48.0.62	0.015*

Table 3 characteristics at the end of 6 month

Variables	Intervention group (n = 47)	Control group (n = 45)	P value
Vitamin D (ng/ml)	39.04±7.88	14.90±2.67	<. 001*
BMI (kg/m2)	23.85±2.79	22.97±4.36	0.252
FPG (mg/dl)	117.32±9.39	129.07±16.67	<. 001*
PPG (mg/dl)	195.52±17.36	209.17±16.63	<. 001*
HbA1c (%)	7.10±0.35	7.40 ±0.51	<. 001*
SGPT (IU/l)	27.87±4.30	28.89±3.68	0.227
SGOT (IU/l)	30.67±4.88	31.57±4.91	0.378
S cr.(mg/dl)	0.82±0.13	0.83±0.13	0.860
BUN(mg/dl)	10.50±1.02	10.99±1.31	0.049*

DISCUSSION:

Our result revealed that add-on therapy of vitamin D with metformin and teneligliptin leads to improvement in glycemic control (FPG, PPG, HbA1c) in type2 diabetic patients with vitamin D deficiency. Most of the studies have shown an inverse association between serum 25-OHD and glycemia in type 2 DM^14,22. While other studies have shown contradictory results regarding glucose control following vitamin D supplementation^24,25. A study by Nwosu et al found that in Type II diabetes mellitus patients, supplementing with Vitamin D for three months resulted in a significant increase in 25(OH)D (p = 0.015). they have concluded that HbA1c decreased from 8.5±2.9% at baseline to 7.7±2.5% in Type II diabetics²⁶. Also, Hasan Qader et al resulted that the supplementation of vitamin D could decrease HbA1c²⁷. And these studiesare quite similar to our study but they have given vitamin D only for approx.three months, while vitamin D has been given up to six months in the present study.

In another study, participants received daily vitamin D3 supplements for 16 weeks to investigate the effects on HbA1C. However, in this double-blind, randomized, placebo-controlled study, despite a mean increase in 25(OH) D levels from 29 to 49nmol/L after the intervention, HbA1c levels did not improve²⁸. In contrast with the present study, they included only healthy subjects and they administered oral vitamin D per day, as opposed to a weekly and monthly dose in the present study.

Several other interventional studies on type two diabetes with concurrent vitamin D deficiency showed improvement in glycemic control after the intervention of vitamin D^29-31. Insulin resistance and pancreatic beta-cell dysfunction are postulated as mechanisms responsible for impaired glucose control in patients with vitamin D deficiency. In addition to these observations, the discovery of vitamin D receptors in beta-cell³² And the finding that mice lacking functional vitamin D receptors secrete less insulin³³ suggests vitamin D has a significant role in regulating the function of beta cells.

A possible mechanism to explain the proposed link between calcium insufficiency and diabetes risk is abnormal intracellular calcium regulation, which affects both insulin sensitivity and insulin release^34,35. As a result, it is suggested that correcting vitamin D deficiency can improve glycemic management by correcting the underlying abnormalities in insulin secretion and insulin resistance. Interestingly in our study BUN is improved significantly in the interventional group. However, it was a slight improvement. That indicated vitamin D can improve kindly function in diabetic patients. Despite the fact that it was not intended to investigate this parameter.

CONCLUSION:

Our study suggested, that add-on therapy of Vitamin D improved the glycemic parameters of type two diabetes mellitus with concurrent vitamin D deficiency over the course of the study. Hence all patients with T2DM should have their vitamin D levels checked and, if found deficient, they should be supplemented with vitamin D.

CONFLICT OF INTEREST:

No conflicts of interest.

ACKNOWLEDGMENTS:

I would like to thank to the Mayo Institute of Medical Sciences for inspiritment and logistic support.

REFERENCES:

1. GBD 2019 Risk Factors Collaborators. Global burden of 87 risk factors in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet. 2020; 396(10258): 1223–49. http://dx.doi.org/10.1016/S0140-6736(20)30752-2

2. Geetha V, Sahu SK, Susila C. Assess quality of life (QOL) and glycemic level among type 2 diabetic patients in global hospital and research centre and its units, sirohi, Rajasthan. Asian J Nurs Educ Res. 2017;7(4): 577.http://dx.doi.org/10.5958/2349-2996.2017.00112.4

3. Kumar DRA, Assistant Professor, Karnataka Institute of Endocrinology and Research Bangalore, Karnataka, India. A comparative study to determine vitamin D status in type 2 diabetes and normal subjects in south India. Int J Med Res Rev. 2017;5(10):888–93. http://dx.doi.org/10.17511/ijmrr.2017.i10.03

4. American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2014;37 Suppl 1(Supplement_1): S81-90.http://dx.doi.org/10.2337/dc14-S081

5. Goyal R, Jialal I. Diabetes Mellitus Type 2. Stat Pearls Treasure Island (FL). 2021;

6. Suraj B, Tripathi CD, Biswas K, Padhy BM, Arora T. A comparative evaluation of safety, efficacy and cost-effectiveness of three add-on treatment regimens in type 2 diabetics; Not controlled by metformin alone. Res J Pharm Technol. 2015;8(1):44.http://dx.doi.org/10.5958/0974-360x.2015.00009.8

7. Stegbauer C, Falivena C, Moreno A, Hentschel A, Rosenmöller M, Heise T, et al. Costs and its drivers for diabetes mellitus type 2 patients in France and Germany: a systematic review of economic studies. BMC Health Serv Res. 2020;20(1):1043.http://dx.doi.org/10.1186/s12913-020-05897-w

8. Subashree R, Arjunkumar R. Vitamin D Deficiency in Periodontal Health. Research J Pharm and Tech. 2014;7(2):248–52.

9. Shwetha MN, Priya PNC. Knowledge regarding vitamin D deficiency among students. Asian J Nurs Educ Res. 2019;9(1):66. http://dx.doi.org/10.5958/2349-2996.2019.00013.2

10. Berridge MJ. Vitamin D deficiency and diabetes. Biochem J2017;474(8):1321–32. http://dx.doi.org/10.1042/BCJ20170042

11. Mattila C, Knekt P, Männistö S, Rissanen H, Laaksonen MA, Montonen J, et al. Serum 25-hydroxyvitamin D concentration and subsequent risk of type 2 diabetes. Diabetes Care 2007;30(10):2569–70. http://dx.doi.org/10.2337/dc07-0292

12. Gupta S, Aparna P, Muthathal S, Nongkynrih B. Vitamin D deficiency in India. J Family Med Prim Care 2018;7(2): 324.http://dx.doi.org/10.4103/jfmpc.jfmpc_78_18

13. Subramanian A, Nigam P, Misra A, Pandey RM, Mathur M, Gupta R, et al. Severe vitamin D deficiency in patients with Type 2 diabetes in north India. Diabetes Manag (Lond) 2011;1(5):477–83. http://dx.doi.org/10.2217/dmt.11.38

14. Ozfirat Z, Chowdhury TA. Vitamin D deficiency and type 2 diabetes. Postgrad Med J 2010;86(1011):18–25; quiz 24. http://dx.doi.org/10.1136/pgmj.2009.078626

15. Borissova AM, Tankova T, Kirilov G, Dakovska L, Kovacheva R. The effect of vitamin D3 on insulin secretion and peripheral insulin sensitivity in type 2 diabetic patients. Int J Clin Pract. 2003;57(4):258–61.

16. Chiu KC, Chu A, Go VLW, Saad MF. Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr. 2004; 79(5): 820–5. http://dx.doi.org/10.1093/ajcn/79.5.820

17. Bichala PK, Kumar KJ, Suthakaran R, Shankar C. Development and validation of an analytical method for the estimation of metformin and teneligliptin in its bulk and tablet dosage form by using RP-HPLC. Asian J Pharm Anal. 2020;10(1):11. http://dx.doi.org/10.5958/2231-5675.2020.00003.4

18. Maheshwari P, Shanmugarajan TS. Evaluation of prescribing practices of metformin in patients with type-2 diabetes mellitus. Res J Pharm Technol. 2019; 12(2): 531. http://dx.doi.org/10.5958/0974-360x.2019.00093.3

19. Daharwal SJ, Rao SP, Singh VK, Dwivedi C, Singh VD. Comparative evaluation of marketed formulations of Metformin HCl. available in India. Asian J Res Chem. 2015;8(7): 441.http://dx.doi.org/10.5958/0974-4150.2015.00070.x

20. Soumya K, Susanna S, Murthy TEGK. In vitro dissolution studies on commercial brands containing immediate release pioglitazone and metformin hydrochloride extended-release tablets. Res J Pharm Dos Forms Technol. 2017; 9(1): 15. http://dx.doi.org/10.5958/0975-4377.2017.00003.9

21. Annapurna MM, Naik RR, Pratyusha SM. Simultaneous spectrophotometric determination of compounds: Application to an anti-diabetic formulation of Teneligliptin and Metformin. Res J Pharm Technol. 2020;13(4): 1938.http://dx.doi.org/10.5958/0974-360x.2020.00349.2

22. Kajbaf F, Mentaverri R, Diouf M, Fournier A, Kamel S, Lalau J-D. The association between 25-hydroxyvitamin D and hemoglobin A1c levels in patients with type 2 diabetes and stage 1-5 chronic kidney disease. Int J Endocrinol. 2014; 2014:142468.http://dx.doi.org/10.1155/2014/142468

23. Randhawa FA, Mustafa S, Khan DM, Hamid S. Effect of Vitamin D supplementation on reduction in levels of HbA1 in patients recently diagnosed with type 2 Diabetes Mellitus having asymptomatic Vitamin D deficiency. Pak J Med Sci Q. 2017;33(4):881–5. http://dx.doi.org/10.12669/pjms.334.12288

24. Orwoll E, Riddle M, Prince M. Effects of vitamin D on insulin and glucagon secretion in non-insulin-dependent diabetes mellitus. Am J Clin Nutr. 1994; 59(5): 1083–7. http://dx.doi.org/10.1093/ajcn/59.5.1083

25. Sheth JJ, Shah A, Sheth FJ, Trivedi S, Lele M, Shah N, et al. Does vitamin D play a significant role in type 2 diabetes? BMC Endocr Disord. 2015;15(1). http://dx.doi.org/10.1186/s12902-015-0003-8

26. Nwosu BU, Maranda L. The effects of vitamin D supplementation on hepatic dysfunction, vitamin D status, and glycemic control in children and adolescents with vitamin D deficiency and either type 1 or type 2 diabetes mellitus. PLoS One. 2014;9(6): e99646. http://dx.doi.org/10.1371/journal.pone.0099646

27. Sofihussein HQ, Al-Naqshabandi AA, Sami HF, Saeed MMM. Effect of vitamin d supplement on the risks of cardiovascular disease in patients with type 2 diabetes in the Kurdistan region of Iraq. Res J Pharm Technol. 2020; 13(9): 4125. http://dx.doi.org/10.5958/0974-360x.2020.00728.3

28. Madar AA, Knutsen KV, Stene LC, Brekke M, Meyer HE, Lagerløv P. Effect of vitamin D3 supplementation on glycated hemoglobin (HbA1c), fructosamine, serum lipids, and body mass index: a randomized, double-blinded, placebo-controlled trial among healthy immigrants living in Norway. BMJ Open Diabetes Res Care. 2014;2(1):e000026. http://dx.doi.org/10.1136/bmjdrc-2014-000026

29. Talaei A, Mohamadi M, Adgi Z. The effect of vitamin D on insulin resistance in patients with type 2 diabetes. Diabetol Metab Syndr. 2013;5(1):8. http://dx.doi.org/10.1186/1758-5996-5-8

30. Upreti V, Maitri V, Dhull P, Handa A, Prakash MS, Behl A. Effect of oral vitamin D supplementation on glycemic control in patients with type 2 diabetes mellitus with coexisting hypovitaminosis D: A parallel-group placebo-controlled randomized controlled pilot study. Diabetes Metab Syndr. 2018; 12(4): 509–12. http://dx.doi.org/10.1016/j.dsx.2018.03.008

31. Banzal N, Desai A. The impact of vitamin D3 supplementation on glycemic control in type-2 diabetes mellitus at a tertiary care hospital. Int J Basic Clin Pharmacol. 2020;9(9): 1417.http://dx.doi.org/10.18203/2319-2003.ijbcp20203629

32. Johnson JA, Grande JP, Roche PC, Kumar R. Immunohistochemical localization of the 1,25(OH)2D3 receptor and calbindin D28k in human and rat pancreas. Am J Physiol. 1994; 267(3 Pt 1): E356-60. http://dx.doi.org/10.1152/ajpendo.1994.267.3.E356

33. Zeitz U, Weber K, Soegiarto DW, Wolf E, Balling R, Erben RG. Impaired insulin secretory capacity in mice lacking a functional vitamin D receptor. FASEB J. 2003;17(3):509–11. http://dx.doi.org/10.1096/fj.02-0424fje

34. Szymczak-Pajor I, Drzewoski J, Śliwińska A. The molecular mechanisms by which vitamin D prevents insulin resistance and associated disorders. Int J Mol Sci. 2020;21(18):6644. http://dx.doi.org/10.3390/ijms21186644

35. Fujita T, Palmieri GM. Calcium paradox disease: calcium deficiency prompting secondary hyperparathyroidism and cellular calcium overload. J Bone Miner Metab. 2000;18(3):109–25. http://dx.doi.org/10.1007/s007740050101

Received on 16.05.2022 Modified on 15.07.2022

Research J. Pharm. and Tech 2023; 16(8):3549-3553.

DOI: 10.52711/0974-360X.2023.00586