Vitamin D and Diabetes
There is evidence between the relationship between vitamin D and Diabetes. Patients who are vitamin D deficient are at higher risk of developing diabetes. The question remains weather or not Vitamin D deficiency worsens the markers of diabetes.
Vitamin D
Vitamin D is a fat soluble vitamin that helps maintain enough calcium and Phosphate levels in the blood. Vitamin D is also needed in bone growth, remodeling and helps promotes calcium absorption from the gastrointestinal tract.
Chronic insufficient levels of vitamin D can cause osteoporosis and in severe cases rickets or osteomalacia. Other functions of vitamin D in the body include cell growth, neuromuscular, immune function and reduction of inflammation.
What is Vitamin D Deficiency?
Vitamin D is most accurately measured by 25(OH)D as it has a long half-life, reflects both vitamin D produced by the skin and obtained through diet. It is hard to get enough vitamin D from food alone, most of the vitamin D is absorbed through the skin from sun light.
Vitamin D levels are categorized as follows:
- < 10 ng/ml = severe deficiency
- 10–24 ng/ml = mild-mod deficiency
- 25–80 ng/ml = optimal
- > 80 ng/ml = toxicity possible
Who is at risk of Vitamin D deficiency:
- Have either liver or kidney dysfunction
- GI disorders (ex. celiac disease, pancreatitis, low bile levels)
- Aging skin
- Darker skin color
- Living at a higher latitude with less yearly sun exposure
- Obesity (BMI >/=30)
Vitamin D deficiency can lead to consequences such as heart attack, poor immune function nd diabetes. Vitamin D also has a protective role in breast cancer, prostate and colon cancer. Your doctor can test you vitamin D level and tell you if you are vitamin D deficient.
Nutritional Vitamin D
Put this foods in your plate: wild cold-water salmon, mackerel, tuna, sardines, cod, and halibut. Also try milk, liver, egg yolks and fortified cereal.
Other ways to get Vitamin D
Sunshine: 15 to 30 minutes of sunlight without any sunscreen, can be done in small doses and not at high noon to avoid sun burn.
Vitamin D supplements for adults: try 4,000 to 5,000 IU daily of vitamin D3 (Cholecalciferol) which is the equivalent of fortified milk. Excessive sun exposure does not cause vitamin D toxicity. Excessive intake in foods that contain large quantities of vitamin D are also very unlikely to cause toxicity. Toxicity is usually the result of high intake of vitamin D containing supplements.
How can Vitamin D deficiency lead to diabetes?
There are vitamin D receptors on different immune cells as well as the beta cells of the pancreas which are responsible for insulin secretion. There are a few different proposed mechanisms of how vitamin D is related to diabetes:
- Active form of vitamin D, 1,25-dihydroxyvitamin D works by:
(1) Improving insulin sensitivity of target cells in the liver, skeletal muscle, and adipose (fat) tissue.
(2) Enhancing and improving B cell function in the pancreas.
(3) Protecting B cells from immune cells by influences proliferation and differentiation of immune cells such as macrophages, dendritic cells, and T cells. - Vitamin D binding proteins, vitamin D receptors and 1alpha-hydroxylase (CYP1alpha) may affect insulin release and result in insulin resistant.
- Affects glucose homeostasis through these mechanism:
(1) Vitamin D helps to maintain adequate calcium levels. When calcium levels are low there is less glucose stimulated insulin secretion that occurs from the B cells.
(2) Inadequate vitamin D can lead to increased PTH levels. This causes decreased glucose uptake by liver, muscle and adipose cells as well as suppression of insulin release. - Vitamin D may stimulate insulin secretion by the vitamin D receptors when there is enough calcium.
**Pancreatic Beta cell make insulin.
Studies finding a correlation between vitamin D Deficiency and type 2 Diabetes (T2DM).
(a) Randhawa F et al. Pak J Med Sci 2017;33:881-885: The purpose of this study was to access the effect of vitamin D supplementation on A1C for patients recently diagnosed with T2DM. Results: There was no significant difference between both groups’ A1C at 1, 3 and 6 months.
(b) Dalgard C et al. Diabetes Care 2011;34:1284-1288: This study looked at 668 participants who were all between the ages of 70-74. They lived in a North Atlantic fishing community where a large part of their diet consisted of fatty fish.
Of the 668 patients 24% had type 2 diabetes mellitus (T2DM) and >50% were considered vitamin D deficient (25(OH)D3 level <20 ng/ml). There were not correlations found between vitamin D deficiency and plasma glucose levels (rs = -0.01; P = 0.78). Vitamin D deficiency was associated with having an 80% increase in sex-adjusted odds of having diabetes compared with sufficient vitamin D levels (OR 1.8, 95% CI 1.23-2.64, P = 0.002). This was also adjusted to take BMI, serum triacylglycerides, serum HDL, PCB exposure, smoking & month of blood sampling into account (OR 1.67, 95% CI 1.11-2.50, P=0.013). Conclusion: Vitamin D deficiency (25(OH)D <20 ng/ml) doubles the risk of newly diagnosed diabetes. This data suggests that vitamin D may play a protective role preventing the development of T2DM.
(c) Pittas AG et al. Diabetes Care 2006;29:650–65: This study consisted of 83,779 women who were all greater than 20 years of age. They found that patients who had low vitamin were at an increased risk of T2DM. When patients were treated with a combination of vitamin D 800 IU and calcium 1,000 mg they found their risk for T2DM was reduced by 33%.
(d) NHANES group (2003– 2006): This group evaluated 9,773 U.S. adults who were greater than 18 years old and had T2DM. They found that there was a correlation between serum vitamin D levels, glucose homeostasis, and the evolution of diabetes. They concluded that patients with an elevated A1C should be evaluated for vitamin D insufficiency.
(e) Talaei A et al. Diabetol Metab Syndr 2013;5:8: This study looked at 100 patients with T2DM between 30 and 70 years old. Of all the patients, 24% had a vitamin D deficiency (25(OH)D ≤20 ng/m). All of these patients were given 50,000 unit of vitamin D3 orally per week for eight weeks. When comparing these patients baseline results to the results at the end of the study they found: Their conclusion was that vitamin D supplementation could reduce insulin resistance in patients with T2DM.
(f) Zhang J et al. Can J Opthalmol 2017;52:S39-44: This study looked at the correlation between diabetic retinopathy (both T1DM and T2DM) and vitamin D deficiency. This was a meta-analysis of 14 observational studies with a total patient population of 10,007. They found a statistically significant association between diabetic retinopathy and vitamin D deficiency. There were statistically significant lower serum vitamin D levels in patients with diabetic retinopathy than in the control group. The higher the degree of vitamin D deficiency, the higher the grade of diabetic retinopathy. Studies finding a correlation between vitamin D Deficiency and diabetes (T1DM)4. Overall there is a lack of studies to support that vitamin D supplementation would improve treatment of T1DM after diagnosis.
(g) Hypponen E, et al. Lancet 2001;358:1500–1503. This study observed that children who took 2,000 IU of vitamin D daily were 80% less likely to develop T1DM.
Conclusion:
There is evidence to the relationship between vitamin D and diabetes. Patients who are vitamin D deficient are at a higher risk of developing diabetes. There is also sufficient evidence showing a positive correlation between vitamin D deficiency and increased insulin resistance, decreased insulin production and higher A1Cs.
Patient with prediabetes and vitamin D deficiency can benefit from Vitamin D supplementation. Patients with diabetes who are obese, have a high A1C and have vitamin D deficiency, can also benefit from Vitamin D supplementation.
***A very special thanks to M. Langton PharmD candidate for her help in gathering information for this topic.
