Retrospective and Prospective Study on Professional Continuous Glucose Monitoring in Insulin-treated Type 2 Diabetes

Diabetes mellitus (DM) is a growing health problem worldwide. The PrevaDiab study, which studied the prevalence of diabetes in Portugal in 2010, estimated a prevalence of 11.7 %, representing about 905 000 patients with diabetes. Taking the demographic evolution of the Portuguese population, these estimates were updated in 2015, and the global prevalence is expected to have risen to 13.3 % of the adult population.

The International Diabetes Federation (idf) recommends the following glycaemia levels: <100 mg dL-1 (eq 5.6 mmol L-1) for impaired fasting glucose and <140 mg dL-1 (eq 7.8 mmol L-1) for 2h glycaemia. Several guidelines recommend frequent glucose measurements as an integral part of the patients' education and self-monitoring.

The percentage of glycated haemoglobin (HbA1c) is used as a long-term glycaemic control proxy, as it gives the mean value of the previous 3 months blood glycose concentrations. idf recommends a maximum 6.5 % HbA1c concentration for all diabetic patients - 7.0 % for type II diabetes mellitus (dm-ii) patients - and, the closer to this value, the fewer risk of complications. The American Diabetes Association (ADA) recommends at least two HbA1c measures per year in controlled patients and three times per year in patients with therapeutic changes and/ or failures.

According with Sartore and collaborators, glucose variability indicators describe the glucose profile of diabetic patients and identify any worsening glycaemic control more accurately than HbA1c tests. However, the capillary glycaemic measure - the standard monitoring blood glucose (smbg) - has some issues that can compromise the optimal diabetes management: with smbg, blood glucose measures are more intermittent, are insufficient to evaluate the glycaemic profile of the patient, and it does not show what happens between two measurements. This situation makes it difficult to interpret and extrapolate information necessary to make adequate decisions in the therapeutic adjustments.

Another clinical important issue is concerned with hypoglycaemia. Hypoglycaemia events limit the efficacy of intensive insulin therapy, especially in patients with great glucose variability, and are associated with increased risk of diabetic complications and cardiovascular disease. The smbg ideal frequency is difficult to establish and consequently, hypo and hyperglycaemic events may be underestimated, even when the measurements and done more frequently than recommended. This underestimation of glucose fluctuations may constitute a critical problem as they have a potential important role in the long term complications occurrence. Several studies report the efficacy of using a professional continuous glucose monitoring (pCGM) device on the detection and reduction of hypoglycaemia and on the detection of hyperglycaemia, alone or compared with SMBG.

Another important parameter is the area under the curve (AUC) in hypoglycaemia, that is, taking into account not only the duration of the events but also its severity.

This information may be crucial for the provider to make clinical decisions and perform therapeutic adjustment in order to control glucose levels more efficiently. Additionally, with a better control of the disease, fewer events are expected to occur showing not only a better clinical situation but also economic benefits of the pCGM over the SMBG alone.

The iPro2 is a pCGM device (from Medtronic Minimed, Northridge, CA) intended to continuously record interstitial glucose levels in persons with dm. It is also intended to be worn for intermittent periods to uncover glycaemic variability and patterns. The data obtained can then be used to maximize treatment strategies to improve patient outcomes.

The study's primary objective is to compare the difference in mean glycated haemoglobin level after clinical decision on diabetes treatment based on pCGM.