The Hypoglycaemia Guide for T1D
Hypoglycaemia in T1D: Recognise, Treat, Prevent
Mid-morning, the CGM buzzes 3.9 mmol/L with the arrow tipping down. A child’s mood drops half a step before the number does. A long-distance runner finishes warm-down to find their hands shaking. Three different bodies, three different days, the same conversation. This guide takes that conversation seriously, in three parts.
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Why a guide, when there is already a Foundations page on hypos
The Foundations page on hypoglycaemia covers the basics that every person living with T1D and every parent of a child with T1D needs in the first six months. It does that job well. This guide picks up where Foundations stops. It is for the person who has lived with the condition long enough to notice the patterns: the warning signs that have quietly faded, the persistent overnight low that no amount of bedtime snack fixes, the post-exercise drop that arrives at midnight rather than at the gym door. Three parts, each with its own conversation.
Hypoglycaemia is the most consistent fear in T1D and the most under-treated in clinic. The fear is rational, the under-treatment is fixable, and the route runs through three conversations: what you are noticing, what you are doing about it, and what would stop it happening as often.
How to use this guide
The three parts are designed to stand alone. Read in order if it helps; jump straight to the part that matches the conversation in front of you if it does not. Each part anchors on the trial evidence, names the trade-off, and closes with what you can actually ask the diabetes team for.
Part 1: Recognising Hypoglycaemia
The two warning systems (the early adrenergic signs, the later neuroglycopenic floor), what changes when awareness fades, the nocturnal pattern most people only see on the overnight CGM report, and the relative-hypo phenomenon for the high-baseline reader.
Part 2: Treating Hypoglycaemia
The adult 15-gram rule, the paediatric weight-based dose at 0.3 g/kg with the 60 kg cap, the glucagon options now available without a reconstitution kit, and how AID changes the protocol after the system has already suspended.
Part 3: Preventing Hypoglycaemia
Four levers, in the order they tend to bite. Basal review, IOB-aware corrections, sick-day rules, exercise timing. The Optimiser ladder is referenced lightly here; the deep treatment of AID settings lives in the AID guide cluster.
Companion: Foundations Hypoglycaemia (page 393)
The first-six-months page, with the weight-based dose chart, the trend-arrow conversation, the glucose-tablets-as-medicine framing. Read this first if you are new to T1D; come back to the three deep parts when you have lived with it a while.
What carries across the three conversations
Hypoglycaemia is not a comfort issue. It is the most common acute complication of T1D, the leading driver of fear of the condition, and the only acute complication with a recognised mortality signal in the literature (the Norwegian childhood-onset cohort tracked by Skrivarhaug 2006 puts dead-in-bed at around four percent of all deaths in childhood-onset T1D, the largest contemporary mortality dataset we have). It is also the complication where the technology era has changed what is possible most. The pivotal trials of low-glucose suspend (Bergenstal 2013, ASPIRE In-Home, NEJM) and predictive low-glucose suspend (Buckingham 2015, paediatric, Diabetes Care) showed for the first time that an algorithm could cut the worst nocturnal lows in half without raising mean glucose; the German DPV registry (Karges 2024) confirmed in 13,922 young people that hybrid closed-loop drops the most dangerous form (hypoglycaemic coma) by around a third.
What does not change is that the family is the constant. The household plan, the school plan, the sport-friend plan, the partner plan; all of them sit alongside the algorithm. The diabetes team is the second constant. Population-level evidence sits underneath every paragraph in this guide; population averages get most of the way; the final twenty percent takes the team and the family conversation.
Acknowledgements
This guide draws on the international hypoglycaemia evidence base curated for GNL Grace, including ISPAD 2024 Chapter 12 (Lange et al), the Cryer HAAF synthesis (NEJM 2013), the McTavish 2011 paediatric weight-based RCT (Pediatric Diabetes), the Husband 2010 paediatric glucose-vs-sucrose-vs-fructose RCT, the Rickels 2016 intranasal glucagon non-inferiority pivotal (Diabetes Care), the Bergenstal ASPIRE 2013 LGS pivotal (NEJM), the Buckingham 2015 paediatric PLGM pivotal (Diabetes Care), the Karges 2024 DPV registry (Lancet Diabetes Endocrinol), and the Pedersen-Bjergaard 2004 European severe-hypo cohort. Voice and structure follow the locked GNL writer specification. Thanks to the families at Birmingham Women’s and Children’s NHS Foundation Trust whose clinic conversations shape every page on this site.