A nomogram to estimate the proportion of patients at hemoglobin A1c target <7% with noninsulin antidiabetic drugs in type 2 diabetes: a systematic review of 137 randomized controlled trials with 39,845 patients.

We assessed the efficacy of noninsulin antidiabetic medications used in current clinical practice (metformin, sulfonylureas, alpha-glucosidase inhibitors, thiazolidinediones, glinides, dipeptidyl peptidase-4 inhibitors, glucagon-like peptide-1 agonists) to reach the HbA1c target < 7% in people with type 2 diabetes. MEDLINE, EMBASE, and the Cochrane CENTRAL were searched from inception through April 2011 for randomized controlled trials (RCTs) involving noninsulin antidiabetic drugs. RCTs had to report the effect of any diabetes medication on the HbA1c levels, to include at least 30 subjects in every arm of the study, and to last at least 12 weeks. Data were summarized across studies using random-effects meta-regression. We found 137 RCTs with 205 arms and 39,845 patients. The proportion of patients who achieved the HbA1c goal ranged from 25.9% (95% CI 18.5-34.9) with alpha-glucosidase inhibitors to 48.6% (95% CI, 53.6) with GLP-1 analogs. Baseline HbA1c was the major determinant of the proportion of patients at HbA1c goal. The meta-regression model with mean baseline HbA1c value, concomitant drug use, and class of drugs as covariates explained almost 67% of the between-study variability. A nomogram was developed to estimate the proportion of patients at target for each noninsulin drug class: for a baseline HbA1c level of 7.5%, all noninsulin drugs, except alpha-glucosidase inhibitors, achieved the HbA1c goal < 7% in more than 50% of patients. Starting or intensifying pharmacological therapy at baseline HbA1c 8% or less was associated with more than 50% of patients at HbA1c goal for most noninsulin drugs.