Result Sets Back the Case for Continuous Monitoring
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Continuous Glucose Monitoring Offers No Pregnancy Benefit

BERLIN – Intermittent use of continuous glucose monitoring during pregnancy failed to improve glycemic control or cut the rate of neonatal macrosomia in a single-center, randomized study with 149 women with diabetes.

In fact, the rate of macrosomia was actually higher in the 76 women with diabetes who used continuous, real-time glucose monitoring during at least 5 weeks of their pregnancy, with a 45% rate, compared with a 34% rate among the 73 control women who used seven-per-day sessions of self-monitoring throughout their pregnancy, a difference that was not statistically significant, Dr. Anna L. Secher said at the meeting.

Mitchel L. Zoler/IMNG Medical Media
Dr. Anna L. Secher

The absence of any discernable benefit from real-time continuous monitoring for any of the measures examined set back the concept that pregnancy could benefit from continuous monitoring, as shown in a prior study of intermittent, continuous monitoring from other investigators (BMJ 2008;337:a1680).

"We were surprised and disappointed with the results," said Dr. Secher, a researcher with the center for pregnant women with diabetes at Rigshospitalet in Copenhagen. The absence of any significant effect from continuous monitoring on macrosomia, prematurity, or episodes of severe neonatal hypoglycemia may have resulted from a cautious control approach promoted by the center’s staff in an effort to minimize hypoglycemia events.

"By focusing on severe hypoglycemia, we might pay a price in hyperglycemic complications," she said.

Another flaw in the Danish study was that the study protocol specified continuous monitoring during only gestational weeks 8, 12, 21, 27, and 33, with each of these weeks culminating with a clinic visit and adjustments to insulin dosages and diet as dictated by the monitoring results. Women in the continuous-monitoring arm were "encouraged" to use continuous monitoring as often as they could during the rest of their pregnancy, but it was not mandatory.

"We made the design intermittent because we knew that limitations in the system would affect compliance," Dr. Secher said. In addition, "we were concerned that women who could use continuous monitoring would be a selected population with limited numbers."

The study enrolled women with type 1 or 2 diabetes at less than 14 weeks’ gestation with a singleton pregnancy. Their average hemoglobin A1c at baseline was about 6.7%, their average body mass index was about 25 kg/m2, and their average duration of diabetes was about 11 years. Eighty percent had type 1 diabetes.

The 76 women who completed the continuous-monitoring arm of the study used the Guardian monitor marketed by Medtronic.

The measurements taken during pregnancy showed identical average levels of HbA1c in both treatment arms throughout the study. The rate of preterm delivery, severe neonatal hypoglycemia, or both was 29% in the continuous-monitoring women and 22% in those who always self-monitored.

A subgroup analysis that focused on the 80% of women with type 1 diabetes failed to change the outcomes. In addition, 22% of the women in the continuous-monitoring group also used an insulin pump, and for these women their pump was hooked up to their continuous monitor. An additional subgroup analysis that focused only on these women also failed to change the outcomes.

Dr. Secher said that she and her associates had no disclosures.

Body

This was a very important study, and it is a shame that it produced a negative result for real-time, continuous glucose monitoring. This represents a step back in the evidence base in support of continuous monitoring. It was very expensive to provide continuous monitors to so many patients, and it was unfortunate that they were able to link the monitors to insulin pumps for only 20% of the women randomized to continuous monitoring. Perhaps having more women on pumps would have improved the performance of continuous monitoring.

The study was well powered. It would have been ideal if they could have tested the efficacy of continuous glucose monitoring throughout pregnancy, without their self-imposed limitation of mandating continuous monitoring during only 5 specific weeks. Results from studies done outside of pregnancy show that continuous monitoring must be used about 80% of the time to have a detectable effect. But their rationale for intermittent monitoring made sense, and results from a prior British study reported in 2008 had shown clear benefits from intermittent use of continuous glucose monitoring in pregnancy (BMJ 2008;337:a1680).

Anne Dornhorst, M.D., is senior diabetologist for Charing Cross and Hammersmith Hospitals in London. She said that she had no relevant disclosures. She made these comments in an interview

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Body

This was a very important study, and it is a shame that it produced a negative result for real-time, continuous glucose monitoring. This represents a step back in the evidence base in support of continuous monitoring. It was very expensive to provide continuous monitors to so many patients, and it was unfortunate that they were able to link the monitors to insulin pumps for only 20% of the women randomized to continuous monitoring. Perhaps having more women on pumps would have improved the performance of continuous monitoring.

The study was well powered. It would have been ideal if they could have tested the efficacy of continuous glucose monitoring throughout pregnancy, without their self-imposed limitation of mandating continuous monitoring during only 5 specific weeks. Results from studies done outside of pregnancy show that continuous monitoring must be used about 80% of the time to have a detectable effect. But their rationale for intermittent monitoring made sense, and results from a prior British study reported in 2008 had shown clear benefits from intermittent use of continuous glucose monitoring in pregnancy (BMJ 2008;337:a1680).

Anne Dornhorst, M.D., is senior diabetologist for Charing Cross and Hammersmith Hospitals in London. She said that she had no relevant disclosures. She made these comments in an interview

Body

This was a very important study, and it is a shame that it produced a negative result for real-time, continuous glucose monitoring. This represents a step back in the evidence base in support of continuous monitoring. It was very expensive to provide continuous monitors to so many patients, and it was unfortunate that they were able to link the monitors to insulin pumps for only 20% of the women randomized to continuous monitoring. Perhaps having more women on pumps would have improved the performance of continuous monitoring.

The study was well powered. It would have been ideal if they could have tested the efficacy of continuous glucose monitoring throughout pregnancy, without their self-imposed limitation of mandating continuous monitoring during only 5 specific weeks. Results from studies done outside of pregnancy show that continuous monitoring must be used about 80% of the time to have a detectable effect. But their rationale for intermittent monitoring made sense, and results from a prior British study reported in 2008 had shown clear benefits from intermittent use of continuous glucose monitoring in pregnancy (BMJ 2008;337:a1680).

Anne Dornhorst, M.D., is senior diabetologist for Charing Cross and Hammersmith Hospitals in London. She said that she had no relevant disclosures. She made these comments in an interview

Title
Result Sets Back the Case for Continuous Monitoring
Result Sets Back the Case for Continuous Monitoring

BERLIN – Intermittent use of continuous glucose monitoring during pregnancy failed to improve glycemic control or cut the rate of neonatal macrosomia in a single-center, randomized study with 149 women with diabetes.

In fact, the rate of macrosomia was actually higher in the 76 women with diabetes who used continuous, real-time glucose monitoring during at least 5 weeks of their pregnancy, with a 45% rate, compared with a 34% rate among the 73 control women who used seven-per-day sessions of self-monitoring throughout their pregnancy, a difference that was not statistically significant, Dr. Anna L. Secher said at the meeting.

Mitchel L. Zoler/IMNG Medical Media
Dr. Anna L. Secher

The absence of any discernable benefit from real-time continuous monitoring for any of the measures examined set back the concept that pregnancy could benefit from continuous monitoring, as shown in a prior study of intermittent, continuous monitoring from other investigators (BMJ 2008;337:a1680).

"We were surprised and disappointed with the results," said Dr. Secher, a researcher with the center for pregnant women with diabetes at Rigshospitalet in Copenhagen. The absence of any significant effect from continuous monitoring on macrosomia, prematurity, or episodes of severe neonatal hypoglycemia may have resulted from a cautious control approach promoted by the center’s staff in an effort to minimize hypoglycemia events.

"By focusing on severe hypoglycemia, we might pay a price in hyperglycemic complications," she said.

Another flaw in the Danish study was that the study protocol specified continuous monitoring during only gestational weeks 8, 12, 21, 27, and 33, with each of these weeks culminating with a clinic visit and adjustments to insulin dosages and diet as dictated by the monitoring results. Women in the continuous-monitoring arm were "encouraged" to use continuous monitoring as often as they could during the rest of their pregnancy, but it was not mandatory.

"We made the design intermittent because we knew that limitations in the system would affect compliance," Dr. Secher said. In addition, "we were concerned that women who could use continuous monitoring would be a selected population with limited numbers."

The study enrolled women with type 1 or 2 diabetes at less than 14 weeks’ gestation with a singleton pregnancy. Their average hemoglobin A1c at baseline was about 6.7%, their average body mass index was about 25 kg/m2, and their average duration of diabetes was about 11 years. Eighty percent had type 1 diabetes.

The 76 women who completed the continuous-monitoring arm of the study used the Guardian monitor marketed by Medtronic.

The measurements taken during pregnancy showed identical average levels of HbA1c in both treatment arms throughout the study. The rate of preterm delivery, severe neonatal hypoglycemia, or both was 29% in the continuous-monitoring women and 22% in those who always self-monitored.

A subgroup analysis that focused on the 80% of women with type 1 diabetes failed to change the outcomes. In addition, 22% of the women in the continuous-monitoring group also used an insulin pump, and for these women their pump was hooked up to their continuous monitor. An additional subgroup analysis that focused only on these women also failed to change the outcomes.

Dr. Secher said that she and her associates had no disclosures.

BERLIN – Intermittent use of continuous glucose monitoring during pregnancy failed to improve glycemic control or cut the rate of neonatal macrosomia in a single-center, randomized study with 149 women with diabetes.

In fact, the rate of macrosomia was actually higher in the 76 women with diabetes who used continuous, real-time glucose monitoring during at least 5 weeks of their pregnancy, with a 45% rate, compared with a 34% rate among the 73 control women who used seven-per-day sessions of self-monitoring throughout their pregnancy, a difference that was not statistically significant, Dr. Anna L. Secher said at the meeting.

Mitchel L. Zoler/IMNG Medical Media
Dr. Anna L. Secher

The absence of any discernable benefit from real-time continuous monitoring for any of the measures examined set back the concept that pregnancy could benefit from continuous monitoring, as shown in a prior study of intermittent, continuous monitoring from other investigators (BMJ 2008;337:a1680).

"We were surprised and disappointed with the results," said Dr. Secher, a researcher with the center for pregnant women with diabetes at Rigshospitalet in Copenhagen. The absence of any significant effect from continuous monitoring on macrosomia, prematurity, or episodes of severe neonatal hypoglycemia may have resulted from a cautious control approach promoted by the center’s staff in an effort to minimize hypoglycemia events.

"By focusing on severe hypoglycemia, we might pay a price in hyperglycemic complications," she said.

Another flaw in the Danish study was that the study protocol specified continuous monitoring during only gestational weeks 8, 12, 21, 27, and 33, with each of these weeks culminating with a clinic visit and adjustments to insulin dosages and diet as dictated by the monitoring results. Women in the continuous-monitoring arm were "encouraged" to use continuous monitoring as often as they could during the rest of their pregnancy, but it was not mandatory.

"We made the design intermittent because we knew that limitations in the system would affect compliance," Dr. Secher said. In addition, "we were concerned that women who could use continuous monitoring would be a selected population with limited numbers."

The study enrolled women with type 1 or 2 diabetes at less than 14 weeks’ gestation with a singleton pregnancy. Their average hemoglobin A1c at baseline was about 6.7%, their average body mass index was about 25 kg/m2, and their average duration of diabetes was about 11 years. Eighty percent had type 1 diabetes.

The 76 women who completed the continuous-monitoring arm of the study used the Guardian monitor marketed by Medtronic.

The measurements taken during pregnancy showed identical average levels of HbA1c in both treatment arms throughout the study. The rate of preterm delivery, severe neonatal hypoglycemia, or both was 29% in the continuous-monitoring women and 22% in those who always self-monitored.

A subgroup analysis that focused on the 80% of women with type 1 diabetes failed to change the outcomes. In addition, 22% of the women in the continuous-monitoring group also used an insulin pump, and for these women their pump was hooked up to their continuous monitor. An additional subgroup analysis that focused only on these women also failed to change the outcomes.

Dr. Secher said that she and her associates had no disclosures.

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AT THE ANNUAL MEETING OF THE EUROPEAN ASSOCIATION FOR THE STUDY OF DIABETES

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Major Finding: Macrosomia affected 45% of mothers with diabetes who had continuous glucose monitoring during pregnancy and 34% of those who did not.

Data Source: Results came from a randomized, controlled, single-center study in 149 pregnant women with diabetes.

Disclosures: Dr. Secher said that she and her associates had no disclosures.