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In people with type 2 diabetes, GLP-1 agonists plus insulin controls blood sugar levels better than insulin or other treatments alone

Eng C, Kramer CK, Zinman B, et al. Glucagon-like peptide-1 receptor agonist and basal insulin combination treatment for the management of type 2 diabetes: a systematic review and meta-analysis. Lancet. 2014 Sep 11. pii: S0140-6736(14)61335-0.

Review question

In people with type 2 diabetes, do glucagon-like peptide-1 (GLP-1) agonist drugs combined with basal insulin control blood sugar levels and weight gain better than other antidiabetic treatments?


Type 2 diabetes is a chronic (long-term) disorder that affects how your body processes sugar (glucose) and other nutrients. Initially, you may be able to manage your diabetes by watching your diet and exercising regularly. However, most people with diabetes will eventually have to use medication, and that may include insulin.

Insulin is initially injected once or twice a day to keep blood sugar levels stable (basal insulin). Sometimes it is also taken as single doses before meals (bolus insulin). Insulin sometimes lowers blood sugar levels too much (hypoglycemia) and can cause weight gain.

GLP-1 agonists are newer, injectable drugs that may help better control blood sugar levels and reduce weight gain.

How the review was done

The researchers did a systematic review, searching for studies that were published up to July 2014.

They found 15 randomized controlled trials with 4,348 people (average age 43 to 61 years, 51% men).

The key features of the studies were:

  • people had type 2 diabetes;
  • GLP-1 agonists, including liraglutide (Victoza®), lixisenatide (Lyxumia®), exenatide (Bydureon®, Byetta®), or albiglutide (Tanzeum®), were taken with basal insulin; and
  • GLP-1 agonists plus basal insulin were compared with other antidiabetic treatments, mostly including basal and/or bolus insulin.

What the researchers found

Compared with other antidiabetic treatments, GLP-1 agonists plus basal insulin:

  • reduced blood sugars and hemoglobin A1c levels (A1c reflects blood sugar levels over the preceding 3 months);
  • increased the number of people with a hemoglobin A1c level less than or equal to 7.0%;
  • reduced weight; and
  • did not affect risk for low blood sugar (hypoglycemia) events.


In people with type 2 diabetes, GLP-1 agonist drugs plus insulin reduce weight and lower blood sugar levels.

Glucagon-like peptide-1 (GLP-1) agonists plus basal insulin* vs other antidiabetic treatments (control) in people with type 2 diabetes


Number of trials and people

Rate of events with GLP-1 agonist plus insulin

Rate of events with control

Absolute effect of GLP-1 agonist plus insulin

Hemoglobin A1c level less than or equal to 7.0%

14 trials (4,267 people)



About 28 more people in 100 reached this goal (from as few as 13 to as many as 48)


11 trials (3,356 people)



No difference in effect†

Hemoglobin A1c level

15 trials (4,348 people)

Does not apply

Does not apply

Reduced by 0.44% (from as little as 0.29% to as much as 0.60%)


12 trials (3,941 people)

Does not apply

Does not apply

Reduced by 3.2 kg (from as little as 1.5 kg to as much as 4.9 kg)

*Insulin injected once or twice per day to keep blood sugar levels stable.

†Although the rates for the 2 groups look a little different, the differences were not statistically significant. This means that the differences could simply be due to chance rather than due to the different treatments.


Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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