Does an insulin pump lower A1C more than shots?

In a Cochrane review of type 1 trials, by about 0.3 points. In the OpT2mise type 2 trial, by about 0.7 points.

How often is insulin in a pump changed?

The NovoLog and Humalog labels say at least every 7 days, or sooner if the pump manual says so.

What happens if a pump stops working?

The labels say blood sugar can rise fast and ketoacidosis can follow, so pump users keep insulin and supplies to inject.

Can any insulin go in a pump?

No. The labels say to check the pump manual. Humalog U-200, for example, must not be used in a pump.

Insulin Pump vs Injections: What the Evidence Shows

Short answer: For some people, modestly. In a Cochrane review of type 1 trials, pumps lowered A1C by about 0.3 points more than multiple daily injections and appeared to cut severe lows, with people preferring them. A type 2 trial found a 0.7-point A1C gain. But labels warn that a pump or infusion set problem can quickly cause high blood sugar and ketoacidosis, so injections stay as a backup.

How a pump works

The NIDDK describes an insulin pump as a small machine that gives steady doses of insulin through the day. A tube pump connects to a thin plastic tube placed under the skin, which stays in for several days; a tubeless pump sticks to the skin with an adhesive pad and is run from a handheld device. The pump can be set to give more or less insulin, and the wearer adds doses at meals. With a continuous glucose monitor and software, some systems adjust insulin on their own, which NIDDK calls an artificial pancreas.

Pumps use rapid-acting insulin such as Humalog U-100 or NovoLog. The labels say to check the pump manual to see if that insulin can be used, and not to mix or dilute it in the pump (section 2.2).

What the trials found

Pump compared with multiple daily injections
Study	People	A1C	Other findings
Misso 2010 (Cochrane review)	23 trials, 976 people with type 1 diabetes	About 0.3 points lower with a pump	Severe lows appeared lower; non-severe lows similar; quality of life favored pumps; no weight difference
OpT2mise (Reznik 2014)	331 people with type 2 diabetes on injections, A1C 8% to 12%	Down 1.1 with a pump vs 0.4 on injections at 6 months	Daily insulin 97 vs 122 units

The Cochrane authors said adverse events, costs and long-term outcomes were not well reported. OpT2mise was open-label, and several of its authors worked for the pump maker.

Pump rules in the insulin labels

Change the insulin in the reservoir at least every 7 days, or sooner if the pump manual says so (NovoLog and Humalog).
Change the infusion set and site as the pump manual says, and rotate sites to avoid skin lumps (section 2.2).
Do not expose insulin in the reservoir to temperatures above 98.6°F (37°C); NovoLog says to throw out insulin that has been.
A pump or infusion set failure, or degraded insulin, can rapidly lead to high blood sugar and ketoacidosis. Pump users must be trained to inject insulin and keep a backup on hand (section 5.8).

NovoLog adds that a blocked, leaking, kinked or disconnected line can cause this, and that if it cannot be fixed quickly, the person should switch to injections and call the clinician.

Choosing between them

NIDDK says the way insulin is taken depends on lifestyle, insurance and preference, and suggests talking it through with the doctor. A pump means wearing a device and handling site changes; injections mean more needles but no hardware to fail. Dose Track logs injected doses with site and time, and can hold notes on pump site changes and backup injections.

Read more on Dose Track: Diabetic ketoacidosis · Humalog vs NovoLog · How to store Humalog · HbA1c

General education drawn from labels, public health agencies and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your medicine are the final word. Questions for other users? Ask in the Dose Track community.

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