Continuous Glucose Monitoring Versus Self-monitoring of Blood Glucose in Type 2 Diabetes Mellitus: A Systematic Review with Meta-analysis

Abstract

Every eleventh adult has diabetes, and every third has prediabetes. Over 95% of diabetics are of type 2. It is well established that diabetes doubles the risk of heart disease and stroke apart from increasing the risk of microvascular complications. Hence, strict glycemic control is necessary. However, it increases the risk of hypoglycemia, especially in patients with longstanding diabetes. Continuous glucose monitors (CGM) use a sensor to continuously measure the glucose levels in the interstitial fluid every 10 seconds and gives out mean values every five minutes. CGMs are emerging tools in the management of type 2 diabetes. The prime objective of this review is to find out if there is enough supporting evidence, suggesting that continuous glucose monitoring is more effective than self-monitoring of blood glucose (SMBG) in type 2 diabetes. We conducted a systematic literature search in Medline (PubMed) looking for any studies addressing our objective. It is observed that there is a varying level of evidence supporting that employing a CGM can reduce glycated hemoglobin (HbA1c), hypoglycemic events, and increase patient satisfaction. However, some studies reported no significant benefits. This systematic review with meta-analysis concludes that the use of CGM in type 2 diabetes mellitus (T2DM) is beneficial, as it significantly reduces HbA1c compared to the usual method of SMBG. The pooled mean difference in HbA1c was -0.25 (-0.45, -0.06) and statistically significant (at p = 0.01) when comparing CGM to SMBG.

Keywords: continuous glucose monitor; glucose variability; real-time glucose monitoring; self-monitoring of blood glucose; time in range; type 2 diabetes mellitus.

Figure 1. Summary of study flow (PRISMA flow diagram)

PRISMA = preferred reporting items for systematic reviews and meta-analyses, RCT = randomised controlled trial, n = number of results

Figure 2. Illustrative summary of RoB of the RCTs

RoB = Risk-of-bias, RCT = randomized control trials

Figure 3. Mean difference of HbA1c between CGM and SMBG groups at the end of respective studies and their pooled analysis

CGM = continuous glucose monitoring, SMBG = self-monitoring of blood glucose, SD = standard deviation, CI = confidence interval

Figure 4. Funnel plot for the five RCTs comparing CGM to SMBG in T2DM

MD = mean difference, SE = standard error, RCTs = randomized control trials, CGM = continuous glucose monitor, SMBG = self-monitoring of blood glucose, T2DM = type 2 diabetes mellitus