Swedish Study: Missing One Insulin Shot a Week Hurts Blood Sugar

Swedish Researchers Use Smart Pens to Catch Missed Insulin Doses — With Striking Results

A study from Sweden, conducted at the Center for Diabetes, Academic Specialist Center in Stockholm and published in the Journal of Diabetes Science and Technology (2024), reveals something many patients and clinicians have long suspected but couldn't easily measure: missed basal insulin injections are more common than we think, and even one skipped dose per week can meaningfully harm blood sugar control.

What Makes This Study Unique

Most US-based research on insulin adherence relies on pharmacy refill records or patient self-reporting — both notoriously unreliable. This Swedish study took a different approach by combining two powerful real-world tools: continuous glucose monitors (CGMs) and smart insulin pens (NovoPen 6), which digitally log every injection with a timestamp. That combination gave researchers something rare: accurate, objective data on exactly when insulin was — and wasn't — given.

This kind of real-world, device-driven study design is more common in Scandinavian healthcare systems, where integrated digital health infrastructure makes large-scale data collection more feasible than in the fragmented US system.

What the Researchers Found

The study followed 32 adults with Type 1 diabetes over 315 two-week periods, generating 4,410 days of usable CGM data. A missed basal dose was defined as a gap of 40 hours or more between injections.

• There was a 22% probability of missing at least one basal insulin dose in any given two-week window
• Missed doses were linked to higher average blood sugar levels
• Patients spent less time in range (70–180 mg/dL) — the key metric for good diabetes management
• The Glucose Management Indicator (GMI), a CGM-based estimate similar to A1C, also worsened
• Age and sex made no significant difference — this was a universal pattern

Why This Matters for US Patients

Current American Diabetes Association (ADA) guidelines emphasize the importance of basal insulin consistency for people with Type 1 diabetes, but they don't specifically quantify how much a single missed dose can hurt. This Swedish data puts hard numbers behind that guidance — and the findings are sobering. A roughly 1-in-5 chance of missing a dose every two weeks adds up quickly over months and years, quietly eroding long-term blood sugar control without patients or providers realizing why.

For US patients managing Type 1 diabetes with daily injections, this research underscores the value of tools that help track and remind — whether that's a smart pen, a CGM app, or a structured daily routine.

A Note on Measurements

The study's time-in-range target of 70–180 mg/dL matches exactly with ADA-recommended targets for most adults with Type 1 diabetes, so no conversion is needed for US readers.

Bottom Line

This first-of-its-kind Swedish study uses real injection data — not estimates — to prove that basal insulin adherence is a genuine, measurable challenge, and that missing even one dose a week carries real consequences for blood sugar control.

If you're managing Type 1 or Type 2 diabetes with basal insulin and want to explore tools, trackers, and supplies that support better daily consistency, visit mdsdiabetes.com for resources tailored to your needs.