Effect of vitamin D supplementation on the efficacy of anti-diabetic drugs in streptozotocin- induced albino Wistar rat model

Abstract

Background: Diabetes mellitus (DM) is a major health challenge that has reached alarming levels worldwide; and due to limitations of existing therapies, the disease has remained an enduring public threat for several decades. Vitamin D deficiency has been shown to play an important role in the pathogenesis of diabetes mellitus as it can affect several key processes in the development of diabetes and its complications, such as pancreatic insulin secretion, peripheral insulin resistance, persistence of systemic inflammation, and immune activation.  This study aims at assessing the suitability of vitamin D as a therapeutic adjuvant in the management of diabetes mellitus.

Methods: The effect of vitamin D supplementation was tested on three different drugs, including the typical type 1 DM Glibenclamide therapy, metformin for type 2 DM, and a category 3 Improved Traditional Medicine (coded as ITM-1) under investigation at the Medical Research and Applied Biochemistry Laboratory of the University of Buea. This research focused on acute hypoglycemic/anti-hyperglycemic effects in Oral Glucose Tolerance Test and sub-acute antidiabetic effects in streptozotocin-rat model. For the latter, fasting blood sugar and body weight were measured on days 0, 5, 10, 15, and 21. Other clinical markers included food and water intakes, and daily urine volume. The effects on selected vital organs were equally assessed, notably the liver (serum level of hepatic transaminases) and kidney (serum creatinine and urea).

Results: This study showed that vitamin D supplementation significantly enhanced the activity of all three anti-diabetic drugs through both their hypoglycemic and anti-hyperglycemic activity (post-prandial peak suppression) as well as the sub-acute anti-diabetic activity (a significant improvement on clinical markers, prevention of diabetic and metformin-induced nephropathy). The micronutrient showed an improvement in renal function which was evidenced by the significant decrease in creatinine and urea serum levels (p<0.01).

Conclusion: Findings from the present work suggested the potential of vitamin D as a therapeutic adjuvant for the management of Type 2 Diabetes Mellitus.