Who doesn't sometimes need a little help navigating life with diabetes? That's why we offer Ask D'Mine, our weekly advice column, hosted by veteran type 1 , diabetes author and educator Wil Dubois.

This week, Wil's tackling two questions relating to continuous glucose monitors and some of those nuanced questions that come with trying to navigate that diabetes tech... He has some opinions, of course, and maybe you'll have some thoughts to share in comments too.

{btw, have diabetes-related questions of your own? Email us at AskDMine@diabetesmine.com}


Scott, type 1 from Ohio, writes: Hi, I'm wondering if you have an "inside scoop" on the new Software 505 update from Dexcom? Supposed to dramatically improve accuracy. I just downloaded it and am starting to use it, but would love to hear from anyone "in the know" if it's really that much better. I ask because I'm a former Freestyle Navigator user... and have never seen the Dexcom to be even close to the accuracy I used to get from the Navigator. Really hoping this software update helps (significantly).

Wil@Ask D'Mine answers: Sorry to disappoint, Scott, but beyond the news report published here at the 'Mine on Nov. 18, I'm relatively scoopless on this front. What little I know is this: The 505 Software is the same algorithm used in much of the artificial pancreas research around the world and the FDA just recently gave their blessing to Dexcom to include the algorithm in all their G4 CGM systems. Brand new G4 receivers will ship with it already built-in, and those of us with the existing systems can upgrade for free online.

On the day of the announcement I tried to upgrade mine, but apparently so did every Dexcom user in the country, and we crashed their system. It was down for days, and I got tired of trying. It gave me PTSD of my attempts to sign up for health insurance last year. I'll update my Dex eventually, but for me anyway, the old G4 is plenty accurate for my needs.

Still, better is better. Right? So how much better is it supposed to be?


Dexcom says it's better by about 4% in MARD, the measure of CGM accuracy. Yes, it went from 13% to 9% (lower is a better score in this case). What does that mean in the trenches? Hell, I don't know. But Dex says this new software makes their CGM the most accurate on the planet, even better than the old Navigators that could only boast a 12% MARD.

And while I may not have any first-hand observations, reports from D-peeps in the field are so far positive. Actually, be sure to take a peek at our recent post from my friend and editor, MikeH, who converted to the new algorithm a few days after it was approved. He wrote:


Yep, my beloved CGM does seem to be more accurate and responding more quickly to my blood sugar changes — especially in the low range. I've also noticed my G4 receiver reflects more dramatically the shifts in blood sugar, more immediately letting me know when these big jumps or drops happen instead of delaying the changes and making them appear more gradual trends.


But unfortunately, on the higher end of the BG spectrum, I'm noticing my results do seem skewed more often and way off from what my meter's showing. This is especially true when it's time to calibrate, and the readings have been 100+ points off. That's a little unnerving for me, as it's not been the case before this update.

Anyhow, it seems I'm not alone. I've seen several people commenting that it's more accurate on that lower end, though some have also reported more fluctuations and quicker arrow changes than before. And others have just not noticed any difference. As with everything in D, your sensor performance may vary.


Probably true, it's another example of Your Diabetes May Vary. Of course, I got miserable results out of my Navigator, but that just fits the theme of we're all different. So I hope the new 505 puts you back in the good space your old gear had you in.

And while we're on the subject of CGM...


Rosemary, type 1 from Arizona, writes: My granddaughter was dx'd in August 2014 with type 1 diabetes. She is bright and very empowered. She gives all her own fingersticks, and shots; now using the pen. My daughter and granddaughter want to have CGM but need help in justifying it to the insurance company. Seems that the insurance company wants age 8, and not 6, even though she could benefit greatly from it. We need an advocate that could help them present it to the insurance company. Their team is supportive, including the endo who will try to persuade them to approve it. Diabetes runs in the family so they're familiar with the treatment. I'm interested in what kind of information others have used to get the technology approved.

Wil@Ask D'Mine answers: You need a strong letter from the endo, and logs showing her blood sugars. The letter should detail the health risk, the potential monetary cost of that risk, and how the CGM will reduce that risk (and cost). It never hurts if the doc suggests there could also be a liability issue for the health plan if they deny this potentially life-saving gear and something bad were to happen. As to the logs, I hate to admit it, but a few scary lows always seem to help the approval process, so if she's had any be sure to include them, even if they were a while back. But for God's sake don't create any. I once actually had a patient so desperate for a CGM that he intentionally overdosed himself to get the lows his health insurance company "required" to cover CGM.

He nearly killed himself.

Also, it never hurts to ask the insurance company for a Care Coordinator before you ask for the CGM. Care Coordinators are commonly social workers whose jobs are to make sure that patients who might get expensive get connected to the resources they need before actually becoming expensive. But in reality they can become great advocates, and they are on the "inside," knowing how the system works within each health plan. Another plus of having a Insurance DeniedCare Coordinator is that it limits the number of people you have to educate about CGM so you can avoid having the "no, it's not a fingerstick meter" conversation with 500 people in the customer care department.

I never needed to use Care Coordinators before health insurance reform. Now it seems I can't get the simplest things covered for my patients without them.

Once you have all your ducks in a row, start by asking nicely. If they say "no," then demand. If they say "no" again, make a lot of noise. I have no idea where her insurance company is coming up with age 8 over age 6, although they may be using outdated info. I think that at one point in the past some insulin pumps were FDA approved for 8 and up. That let health plans reject younger kids on the basis that the gear wasn't approved for that age range.

But that's not an issue for CGM at your granddaughter's age. For instance, the Dexcom G4 Platinum's pediatric indication from the FDA is from age 2-17 years; so the insurance company has no automatic out in her case by claiming it's not approved for kids her age. And as there's no rational reason for a health plan to adopt a more restrictive age than the one the FDA has approved, I think they are blowing smoke and that the endo can help you clear the air.

Of course, this may be different if we're talking about the other CGM on the market here in the States, from Medtronic. Their newest 530G system is only approved for ages 16 and older right now, but even the earlier Minimed REAL-Time Revel only got regulatory OK for kiddos 7 and up. But again, if you have a doc's backing with prescription on file, then it shouldn't be tough.

I actually had no problem once getting a 3-year-old approved, and that was back before there was any pediatric indication for CGM at all. Oh wait. That's not quite true. They said "no" the first time and I picked up the phone, got ahold of the person who was on point on the denial and told them they had 48 hours to change their minds or I was filing a complaint with the State Corporation Commission and would be holding a press conference telling the media how the big, bad wolf insurance company was trying to kill Little Red Riding Hood by denying her life-saving gear solely to line their pockets. Or words to that effect. I probably used a lot of big medical terms to sound more professional.

Yes, the best tool in your arsenal—because logic, humanity, and common sense don't come into play with health insurance—is that insurance plans hate bad PR. And they hate dealing with the government agencies that oversee them. We got my little patient approved in 24 hours, not the 48.

Hopefully you'll be able to do the same.



This is not a medical advice column. We are PWDs freely and openly sharing the wisdom of our collected experiences — our been-there-done-that knowledge from the trenches. But we are not MDs, RNs, NPs, PAs, CDEs, or partridges in pear trees. Bottom line: we are only a small part of your total prescription. You still need the professional advice, treatment, and care of a licensed medical professional.


Disclaimer: Content created by the Diabetes Mine team. For more details click here.


This content is created for Diabetes Mine, a consumer health blog focused on the diabetes community. The content is not medically reviewed and doesn't adhere to Healthline's editorial guidelines. For more information about Healthline's partnership with Diabetes Mine, please click here.