Importance
Numerous glucose-lowering drugs are used to treat type 2 diabetes.
Objective
To estimate the relative efficacy and safety associated with
glucose-lowering drugs including insulin.
Data
Sources Cochrane Library Central Register of Controlled Trials,
MEDLINE, and EMBASE databases through March 21, 2016.
Study
Selection Randomized clinical trials of 24 weeks’ or longer
duration.
Data
Extraction and Synthesis Random-effects network meta-analysis.
Main
Outcomes and Measures The primary outcome was cardiovascular
mortality. Secondary outcomes included all-cause mortality, serious
adverse events, myocardial infarction, stroke, hemoglobin A1c (HbA1C)
level, treatment failure (rescue treatment or lack of efficacy),
hypoglycemia, and body weight.
Results
A total of 301 clinical trials (1 417 367 patient-months) were
included; 177 trials (56 598 patients) of drugs given as
monotherapy; 109 trials (53 030 patients) of drugs added to
metformin (dual therapy); and 29 trials (10 598 patients) of drugs
added to metformin and sulfonylurea (triple therapy). There were no
significant differences in associations between any drug class as
monotherapy, dual therapy, or triple therapy with odds of
cardiovascular or all-cause mortality. Compared with metformin,
sulfonylurea (standardized mean difference [SMD], 0.18 [95% CI, 0.01
to 0.34]), thiazolidinedione (SMD, 0.16 [95% CI, 0.00 to 0.31]),
DPP-4 inhibitor (SMD, 0.33 [95% CI, 0.13 to 0.52]), and α-glucosidase
inhibitor (SMD, 0.35 [95% CI, 0.12 to 0.58]) monotherapy were
associated with higher HbA1C levels. Sulfonylurea (odds ratio [OR],
3.13 [95% CI, 2.39 to 4.12]; risk difference [RD], 10% [95% CI, 7% to
13%]) and basal insulin (OR, 17.9 [95% CI, 1.97 to 162]; RD, 10% [95%
CI, 0.08% to 20%]) were associated with greatest odds of
hypoglycemia. When added to metformin, drugs were associated with
similar HbA1C levels, while SGLT-2 inhibitors offered the lowest odds
of hypoglycemia (OR, 0.12 [95% CI, 0.08 to 0.18]; RD, −22% [−27%
to −18%]). When added to metformin and sulfonylurea, GLP-1 receptor
agonists were associated with the lowest odds of hypoglycemia (OR,
0.60 [95% CI, 0.39 to 0.94]; RD, −10% [95% CI, −18% to −2%]).
Conclusions
and Relevance Among adults with type 2 diabetes, there were no
significant differences in the associations between any of 9
available classes of glucose-lowering drugs (alone or in combination)
and the risk of cardiovascular or all-cause mortality. Metformin was
associated with lower or no significant difference in HbA1C levels
compared with any other drug classes. All drugs were estimated to be
effective when added to metformin. These findings are consistent with
American Diabetes Association recommendations for using metformin
monotherapy as initial treatment for patients with type 2 diabetes
and selection of additional therapies based on patient-specific
considerations.
It
is important to note that this analysis did not distinguish between
microvascular and macrovascular causes of all cause and
cardiovascular mortality.