Ambient Heat and Risk of Serious Hypoglycemia in Older Adults With Diabetes Using Insulin in the U.S. and Taiwan: A Cross-National Case-Crossover Study

Diabetes Care. 2024 Feb 1;47(2):233-238. doi: 10.2337/dc23-1189.


Objective: To measure the association between ambient heat and hypoglycemia-related emergency department visit or hospitalization in insulin users.

Research design and methods: We identified cases of serious hypoglycemia among adults using insulin aged ≥65 in the U.S. (via Medicare Part A/B/D-eligible beneficiaries) and Taiwan (via National Health Insurance Database) from June to September, 2016-2019. We then estimated odds of hypoglycemia by heat index (HI) percentile categories using conditional logistic regression with a time-stratified case-crossover design.

Results: Among ∼2 million insulin users in the U.S. (32,461 hypoglycemia case subjects), odds ratios of hypoglycemia for HI >99th, 95-98th, 85-94th, and 75-84th percentiles compared with the 25-74th percentile were 1.38 (95% CI, 1.28-1.48), 1.14 (1.08-1.20), 1.12 (1.08-1.17), and 1.09 (1.04-1.13) respectively. Overall patterns of associations were similar for insulin users in the Taiwan sample (∼283,000 insulin users, 10,162 hypoglycemia case subjects).

Conclusions: In two national samples of older insulin users, higher ambient temperature was associated with increased hypoglycemia risk.

MeSH terms

  • Aged
  • Cross-Over Studies
  • Diabetes Mellitus*
  • Hot Temperature
  • Humans
  • Hypoglycemia* / chemically induced
  • Hypoglycemia* / epidemiology
  • Hypoglycemic Agents
  • Insulin / adverse effects
  • Insulin, Regular, Human
  • Medicare
  • Retrospective Studies
  • Taiwan / epidemiology
  • United States / epidemiology


  • Insulin
  • Hypoglycemic Agents
  • Insulin, Regular, Human