The objective of this study was to investigate whether glycated hemoglobin (HbA1c) is a valid surrogate for evaluating the effectiveness of antihyperglycemic drugs in diabetes mellitus (DM) trials.

We conducted a systematic review of placebo-controlled randomized clinical trials (RCTs) evaluating the effect of a treatment on HbA1c (mean difference between groups) and clinical outcomes (relative risk of mortality, myocardial infarction, stroke, heart failure, and/or kidney injury) in patients with DM. Then, we investigated the association between treatment effects on HbA1c and clinical outcomes using regression analysis at the trial level. Lastly, we interpreted the correlation coefficients (R) using the cut-off points suggested by the Institute for Quality and Efficiency in Healthcare (IQWiG). HbA1c was considered a valid surrogate if it demonstrated a strong association: lower limit of the 95 percent confidence interval (95 percent CI) of R greater than or equal to .85.

Nineteen RCTs were identified. All studies included adults with type 2 DM. None of the associations evaluated was strong enough to validate HbA1c as a surrogate for any clinical outcome: mortality (R = .34; 95 percent CI −.14 to .69), myocardial infarction (R = .20; −.30 to .61), heart failure (R = .08; −.40 to .53), kidney injury (R = −.04; −.52 to .47), and stroke (R = .81; .54 to .93).

The evidence from multiple placebo-controlled RCTs does not support the use of HbA1c as a surrogate to measure the effectiveness of antihyperglycemic drugs in DM studies.

International guidelines on diabetes control strongly encourage the setting-up of therapeutic educational programs (TEP). However, more than half of the patients fail to control their diabetes a few months post-TEP because of a lack of regular follow-up by medical professionals. The DIAB-CH is a TEP associated with the follow-up of diabetic patients by the community pharmacist.

To compare the glycated hemoglobin (HbA1c) and body mass index (BMI) in diabetic patients of Control (neither TEP-H nor community pharmacist intervention), TEP-H (TEP in hospital only) and DIAB-CH (TEP-H plus community pharmacist follow-up) groups.

A comparative cohort study design was applied. Patients included in the TEP-H from July 2017 to December 2017 were enrolled in the DIAB-CH group. The TEP-H session was conducted by a multidisciplinary team composed of two diabetologists, two dieticians and seven nurses. The HbA1c level and the BMI (when over 30 kg/m2 at M0) of patients in Control (n = 20), TEP-H (n = 20) and DIAB-CH (n = 20) groups were collected at M0, M0 + 6 and M0 + 12 months. First, HbA1c and BMI were compared between M0, M6 and M12 in the three groups with the Friedman test, followed by the Benjamini-Hochberg post-test. Secondly, the HbA1c and BMI of the three groups were compared at M0, M6 and M12 using the Kruskal-Wallis test.

While no difference in HbA1c was measured between M0, M6 and M12 in the Control group, Hb1Ac was significantly reduced in both TEP-H and DIAB-CH groups between M0 and M6 (P = 0.0072 and P = 0.0034, respectively), and between M0 and M12 only in the DIAB-CH group (P = 0.0027). In addition, a significant decrease in the difference between the measured HbA1c and the target assigned by diabetologists was observed between M0 and M6 in both TEP-H and DIAB-CH groups (P = 0.0072 and P = 0.0044, respectively) but only for the patients of the DIAB-CH group between M0 and M12 (P = 0.0044). No significant difference (P > 0.05) in BMI between the groups was observed.

The long-lasting benefit on glycemic control of multidisciplinary group sessions associated with community pharmacist-led educational interventions on self-care for diabetic patients was demonstrated in the present study. There is thus evidence pointing to the effectiveness of a community/hospital care collaboration of professionals on diabetes control in primary care.