Diabetes and Renal Function
Ms. Ward: In some of the studies, there seems to be a higher risk in patients with diabetes. Is there any reason why that would be?
Dr. Budoff: I can’t think of a reason exactly why with diabetes per se, except for renal disease. Patients with diabetes have more intrinsic renal disease, proteinuria, and even a reduced eGFR. We’ve seen that the kidney is very strongly tied to this. We have a very strong relationship, in work I’ve done a decade ago now, showing that calcium supplementation (in the form of phosphate binders) in patients on dialysis or with advanced renal disease is linked to much higher coronary calcium progression.
We did prospective, randomized trials showing that calcium intake as binders to reduce phosphorus led to more coronary calcium. We always thought that was just relegated to the renal population, and there might be an overlap here with the diabetes and more renal disease. I have a feeling that it has to do with more of that. It might be regulation of parathyroid hormone as well, which might be more abnormal in patients with diabetes.
Avoid Supratherapeutic Vitamin D Levels
Ms. Ward:: What are you telling your patients?
Dr. Budoff: I tell patients with normal kidney function that the bone will modulate 99.9% of the calcium uptake. If they have osteopenia or osteoporosis, regardless of their calcium score, I’m very comfortable putting them on supplements.
I’m a little more cautious with the vitamin D levels, and I keep an eye on that and regulate how much vitamin D they get based on their levels. I get them into the normal range, but I don’t want them supratherapeutic. You can even follow their calcium score. Again, we’ve shown that if you’re taking too much calcium, your calcium score will go up. I can just check it again in a couple of years to make sure that it’s safe.
Ms. Ward:: In terms of vitamin D levels, when you’re saying “supratherapeutic,” what levels do you consider a safe amount to take?
Dr. Budoff: I’d like them under 100 ng/mL as far as their upper level. Normal is around 70 ng/mL at most labs. I try to keep them in the normal range. I don’t even want them to be high-normal if I’m going to be concomitantly giving them calcium supplements. Of course, if they have renal insufficiency, then I’m much more cautious. We’ve even seen calcium supplements raise the serum calcium, which you never see with dietary calcium. That’s another potential proof that it might be too much too fast.
For renal patients, even in mild renal insufficiency, maybe even in diabetes where we’ve seen a signal, maybe aim lower in the amount of calcium supplementation if diet is insufficient, and aim a little lower in vitamin D targets, and I think you’ll be in a safer place.
Ms. Ward: Is there anything else you want to add?
Dr. Budoff: The evidence is still evolving. I’d say that it’s interesting and maybe a little frustrating that we don’t have a final answer on all of this. I would stay tuned for more data because we’re looking at many of the epidemiologic studies to try to see what happens in the real world, with both dietary intake of calcium and calcium supplementation.
Ms. Ward: Thank you very much for joining me today.
Dr. Budoff: It’s a pleasure. Thanks for having me.
Dr. Budoff disclosed being a speaker for Amarin Pharma.
A version of this article appeared on Medscape.com.