When to use technology: REPOSE, GOLD, DIAMOND and REPLACE-BG provide more evidence

The REPOSE study (summarised alongside) was designed to test whether initiating insulin pump therapy at the same time as providing structured education for people with type 1 diabetes on multiple daily injection (MDI) therapy resulted in any benefit in terms of HbA_1c and episodes of moderate and severe hypoglycaemia.

The conclusion was that there was no improvement in outcomes when pump therapy was added at the same time as Dose Adjustment for Normal Eating (DAFNE) training. Both groups showed an improvement in HbA_1c and rates of severe hypoglycaemia. There was a greater reduction in HbA_1c in the group starting pump therapy, with the adjusted difference in response being −2.7 mmol/mol (0.24%), but this was not of statistical or clinical significance.

It is crucial to emphasise that the cohort enrolled in the study was not eligible for insulin pump therapy as recommended by NICE (2008) TA151 guidance. NICE recommend insulin pump therapy for people with type 1 diabetes aged ≥12 years who have an HbA_1c >69 mmol/mol (8.5%) or disabling hypoglycaemia on MDI therapy despite a high level of care, including the provision of structured education. The outcome of REPOSE supports the current pathway for insulin pump therapy in line with TA151 – that all people should have access to appropriate structured education and, only after this, if HbA_1c remains elevated or disabling hypoglycaemia is a problem, should insulin pump therapy be offered.

GOLD, DIAMOND and REPLACE-BG
Three randomised controlled trials of continuous glucose monitoring (CGM) effectiveness have recently been published. What do they tell us about the role of CGM? Insulin pump therapy is supported by a positive NICE technology appraisal, which commissioners are expected to fund. The evidence base for CGM has not been robust enough to date for it to have similar backing, although the NICE (2015) NG17 guideline for adults with T1D does advocate the use of CGM, particularly for those with problematic hypoglycaemia, but also for those with an HbA_1c ≥80 mmol/mol (9.5%), provided that CGM results in a fall in HbA_1c to <58 mmol/mol (7.5%). This means that insulin pump therapy is the “go-to” option when HbA_1c levels are elevated on optimised MDI therapy.

GOLD and DIAMOND make a case for CGM to be given equal consideration, however. In DIAMOND, the HbA_1c reduction at 24 weeks was 6.6 mmol/mol (0.6%) greater in the CGM group than the control group, from a mean baseline HbA_1c of 70 mmol/mol (8.6%). GOLD was a crossover design, and the mean reduction in HbA_1c when using CGM compared to conventional treatment was 4.7 mmol/mol (0.43%) over 26 weeks of usage. While those using CGM are cautioned that they should always use a capillary blood glucose (CBG) measurement for decision-making, in real life, CGM readings are often used for this purpose.

REPLACE-BG considered whether a lack of CBG readings – except for calibration and in a few other specific circumstances where CBG readings might be unreliable – was detrimental to glycaemic control. The CGM-only group performed an average of only 0.8 non-calibration CBG readings daily, but there was no difference in parameters of glycaemic control when compared to those using CGM as an adjunct to regular CBG monitoring.

While insulin pump therapy will probably remain the option of choice when attempting to optimise glycaemic control in those for whom MDI with effective structured education has not achieved HbA_1c targets, CGM should be considered as an alternative – particularly for those who have reservations about insulin pump therapy. Improvements in sensor wearability and accuracy mean CGM is an increasingly acceptable alternative, and significant improvements in control can be achieved with a reduced reliance on CBG monitoring.

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