A new trial published in the Journal of Nephropathology has found that vitamin D supplementation helps lower blood pressure in type 2 diabetes.
High blood pressure is very common in people with type 2 diabetes. Two-thirds of people with type 2 diabetes have high blood pressure or report taking medication to help lower blood pressure.
In type 2 diabetes, the body has a difficult time producing enough insulin or using the insulin that is produced from beta-cells in the pancreas. Insulin helps convert sugar and starches into glucose, which insulin then helps the body to store and use for energy. When insulin doesn’t properly store or use glucose, it begins to build up in the blood stream. Any sort of build-up in the blood stream makes the heart have to work harder to move blood throughout the body, which increases blood pressure.
There is a growing body of research that shows a link between vitamin D and type 2 diabetes and blood pressure. Vitamin D may be able to help pancreatic beta cells function better and also help the body be more sensitive to insulin. Furthermore, vitamin D may be able to directly help lower blood pressure by making arterial walls smoother and suppressing the renin-angiotensin system, a system that can increase blood pressure if over-activated.
Because type 2 diabetics are at a very high risk for high blood pressure, researchers out of Iran recently conducted a randomized controlled trial to see if vitamin D may be able to help lower blood pressure among people with type 2 diabetes.
The research team recruited 60 patients with type 2 diabetes. They were then randomized into two groups of 30. For 12 weeks, one group received 50,000 IU/week of vitamin D3 and the other group received a placebo. The researchers wanted to see if high doses of vitamin D had a direct effect on blood pressure among type 2 diabetics.
Here is what the researchers found:
- Average vitamin D levels in the vitamin D group increased significantly from 33.6 ng/ml to 65.6 ng/ml. There was no significant change in vitamin D levels in the placebo group.
- In the vitamin D group, average systolic blood pressure and diastolic blood pressure decreased significantly from 121 mmHg to 110 mmHg and 80.5 mmHg to 76.3 mmHg, respectively. There was no significant change in blood pressure in the placebo group.
The researchers concluded,
“In this study we found that weekly vitamin D supplementation had beneficial effects on the level of blood pressure in type 2 diabetic patients.”
The small sample size and short trial duration means that we cannot know for sure if these results apply to other populations and for how long the effects may last for. Also, while the study group did have high blood pressure at the start of the trial, they weren’t hypertensive, meaning that we don’t know the effect of vitamin D on hypertension in type 2 diabetics. However, based on these results, we would hypothesize that it would have a beneficial effect.
In this study, 50,000 IU/week of vitamin D3 (around 7,000 IU/day) showed a beneficial effect on blood pressure in type 2 diabetes. While larger trials may give us more concrete and clearer results, this study gives evidence that vitamin D supplementation could be used as an add-on therapy to help blood pressure in type 2 diabetes.
Nasri, H. et al. Impact of oral vitamin D (cholecalciferol) replacement therapy on blood pressure in type 2 diabetes pateints; a randomized, double-blind, placebo controlled clinical trial. Journal of Nephropathology, 2014.