Calibration Codes vs. No-Code Technology

Calibration Codes vs. No-Code Technology

Introduction

Older blood glucose meters had to be told which batch of test strips they were reading. You typed in a code number or plugged in a code key whenever you opened a new box; the Accu-Chek Aviva Plus, as the FDA cleared it in 2011, worked this way [5]. A mismatch was common. Two independent studies, cited in a 2006 paper by Bayer researchers, found that 16% of people who check their own blood glucose were using incorrectly coded meters [2].

That error carried real weight. In a 2007 simulation study, the chance that a calculated insulin dose would be off by 3 units reached 22.3% with miscoded meters, compared with 0.49% for correctly coded ones [3].

Ditching Calibration Codes

Each lot of strips responds to glucose a little differently, so a coded meter needs the number that belongs to that lot [2]. People were the weak link in that handoff. No-Code Technology takes them out of it, using one of two methods: Auto-Coding or Universal Calibration.

• Auto-Coding: The meter picks up the lot's calibration information by itself, so it can't be miscoded [2]. In some designs, the strip carries that information in a pattern on its electrical contacts, which the meter reads when the strip goes in.
• Universal Calibration: The manufacturer holds strip lots close enough to one calibration that the meter never needs a code.

From the user's side, both look the same. The FDA's 2011 review of the original OneTouch Verio meter lists "no coding by user", where its predicate, the OneTouch Ultra 2, had the user set a calibration code [6]. Here's what surprised us: autocoded meters didn't just match correctly coded manual meters on insulin dose errors in the 2007 study, they did better. No calculated dose from an autocoded meter was off by more than 2 units [3].

Driving Change

We couldn't find a source showing that ISO 15197, the international accuracy standard for self-testing glucose meters [1], drove the move to no-code strips, so we no longer say it did. The dates don't fit a simple cause and effect. Autocoded meters were already being studied in 2006 [2], seven years before the 2013 edition tightened the limits. The 2003 edition required 95% of results within ±15 mg/dL below 75 mg/dL and within ±20% at or above it; the 2013 edition narrowed that to ±15 mg/dL below 100 mg/dL and ±15% at or above it [8].

Coding errors land well outside either limit. Deliberately miscoded meters in the 2006 study read anywhere from 31.6% low to 60.9% high [2]. A 2008 follow-up modeled what would happen if insulin were dosed from readings like these: the predicted chance of glucose falling to 70 mg/dL or below was 10.40% with miscoded meters, against 2.52% with autocoded meters and 1.46% with correctly coded manual ones [4]. Those figures come from simulations, not observed patients. They also show that the gap that mattered was between miscoded meters and everything else.

The Bottom Line

No-code strips remove a step people got wrong often enough to show up in studies, and the resulting errors were large [2][3]. As of October 2026, current systems such as the Accu-Chek Guide and the Contour Next One are cleared as needing no calibration or coding by the user [7][9]. How much a single reading should change your insulin is a separate question, and a decision for you and your care team.