Do insulin pumps and continuous glucose monitors actually improve outcomes?

Nearly every day in my practice, a patient with diabetes asks me whether he or she should switch from multiple daily insulin injections to an insulin pump.  I often have a discussion with patients about whether or not they should be using a CGM (continuous glucose monitor) to help monitor blood glucose instead of just using SMBG (self-monitoring of blood glucose).  As an endocrinologist, it is very important to be able to advise patients about specifically what these new technologies have to offer them.  Do they decrease mortality?  Do they decrease long-term diabetes complications?  Do they improve glycemic control?  Do they improve quality of life for patients?  Do they lower costs?  All new medical technologies need to undergo a rigorous evaluation and testing with these types of questions in mind.  This is critical not just so that I can be honest and helpful to my patients, but also from the overall perspective of the healthcare system.

In that vein, Yeh et al recently published a meta-analysis in the Annals of Internal Medicine called “Comparative Effectiveness and Safety of Methods of Insulin Delivery and Glucose Monitoring for Diabetes Mellitus: A Systematic Review and Meta-analysis.”

This meta-analysis, funded by AHRQ, looked at the differences between:

  1. MDI vs CSII (multiple daily injections vs continuous subcutaneous insulin infusion)
  2. Type 1 vs type 2 diabetes
  3. SMBG (self-monitoring of blood glucose) vs rt-CGM (real-time continuous glucose monitoring)

What types of studies did they include in their meta-analysis?

  • Studies of adults, adolescents, or children with type 1 or type 2 diabetes mellitus
  • Studies from 1966-2012
  • 19 studies comparing CSII with MDI (>3 injections per day of either basal/bolus insulin or NPH/regular)
  • 10 studies comparing CGM with SMBG (>3 fingersticks per day)
  • 4 studies comparing SAP (Sensor-augmented pump) use with MDI + SMBG

* Studies were excluded if regular insulin was used in the CSII (pump) group (they felt this to be a weakness of prior analyses)

Here is the key data table:

A few things pop out from this table:

  1. Overall, they assessed the strength of evidence as relatively weak.
  2. In children and adolescents, CSII showed no difference in clinical outcomes from MDI.  CSII was better in terms of quality-of-life.
  3. In adults with type 1 diabetes, CSII led to more symptomatic hypoglycemia, but better hemoglobin A1c and quality-of-life.
  4. There were no differences between CSII and MDI in adults with type 2 diabetes.
  5. CGM, whether with an insulin pump or not, led to a benefit in glycemic control without any difference in hypoglycemia.

Some concerns and words of caution when interpreting these results:

  • Meta analyses can always suffer from publication bias.  That is, studies are much more likely to be published if they show positive results.  So it is possible that studies have been done that generated results that would have shown no difference between the two methods being studied, but these may never have been published and thus cannot be included in the meta-analysis.
  • These studies all had durations of 12-52 weeks.  There were no studies reporting on long-term outcomes like micro or macrovascular disease.
  • 24 of the articles (approximately 2/3) were supported by pharmaceutical companies

What does this mean?

According to this meta-analysis, CGMs did improve glycemic control.  Insulin pumps did not appear to have a significant effect on clinical outcomes, but did positively effect quality of life.  Remember that the studies included were all between 12 and 52 weeks, so one major limitation is that any longer-term effects would not be teased out.

While some may discount the quality of life improvements seen with the pump as being less important than clinical outcomes, I caution people from doing so.  In a condition as omnipresent as diabetes, maintaining good quality of life for the patient is critical and a very important goal.

In the end, the decision about whether or not to use one of these devices comes down to a conversation with the patient and their family, based on their personal preferences and what each device might offer them in terms of benefits and harms.  This meta-analysis adds some more information to that conversation.

Finally, this meta-analysis shows that we simply need more data to study so that more concrete conclusions can be drawn.

Quantified Self and Diabetes… the Perfect Match

Take a few minutes and watch this video of Jana Beck from a Quantified Self meeting as she explains how she took data from her Dexcom CGM (continuous glucose monitor) and created her own data visualizations (Thank you to Russ Cucina for sharing this video with me).  I think that the visualizations she created are very cool and obviously helped her in her journey to try out a new method of managing her diabetes with a low carbohydrate diet.

Beyond this particular video, I am also very excited about the Quantified Self movement and its overlap with diabetes.  Type 1 diabetes is a disease that requires patients to monitor their physiologic status on a frequent and routine basis, from food intake to activity levels to glucose levels.  Many people in the Quantified Self movement are voluntarily doing much of the same thing.  While these people never have to have the same concerns of a person with diabetes that, if they feel like “slacking off” for a day, something might go horribly wrong, they are at least starting to develop some empathy and interest.  There is a fantastic synergy here, introducing a new cadre of talented, engaged, and enthusiastic people to the field of diabetes technology.  This is happening whether or not they realize it!  This entire group of people are trying to monitor their every action and learn from the data visualizations… precisely the thing we try to help people with type 1 diabetes do!  I’ve not yet been to one of the QS MeetUp events in San Francisco, but plan to go sometime soon.  I am convinced that advancements in diabetes care will come from the QS movement, whether intentional or accidental.

Tip: If you already know about diabetes and CGM devices, you can skip to minute 6 and start there.  The visualizations start at about minute 8 of the video.

Medtronic makes a first step towards “closed loop” with “low glucose suspend” feature

Medtronic just published results from their ASPIRE study showing decreased time in hypoglycemia for patients using their new “low glucose suspend” feature.  The new system will automatically and temporarily suspend insulin delivery if the patient’s glucose falls below a set threshold value.  In this case, the threshold of <70 mg/dl was used.

Automatic prevention of hypoglycemia is a big step forward in assuring the safety of patients with type 1 diabetes.  What will be an interesting next step will be to see if this data is reproducible in a “normal,” home environment, since this study was done by inducing hypoglycemia through exercise in a research setting.  Though we may or may not see major improvements in long-term clinical outcomes with this new technology, it seems like it may start to reduce the need for waking up with hypoglycemia and having a snack at 4am, and it seems like a step closer to realizing a “closed loop.”

I know that there are a number of patients who use Medtronic pumps and Dexcom sensors because they find the Dexcom sensor more comfortable.   This new feature requires use of both the Medtronic pump and Medtronic sensor in order to create the first step towards a closed-loop system.  I wonder whether this new feature will convince at least a few patients to switch to using a Medtronic sensor.

I’d be curious to hear comments from any patients who are in this situation and what your thoughts are.

Graph below taken from the Diabetes Technology and Therapeutics publication showing glucose values from patients with and without the low glucose suspend feature.

170 million wearable, wireless health and fitness devices by 2017

From mobihealthnews, ABI Research predicts that by 2017, there will be 170 million wearable and wireless health and fitness devices in the US.  While I assume they include CGM (continuous glucose monitor) in these numbers, having more people with diabetes wearing devices like the Jawbone Up or the Fitbit is likely to happen.  The real win will occur when the data from these devices gets truly integrated with glucose data and insulin data to help make future management decisions.  If all the data stays in silos, it’s unlikely to be of much benefit.