Sauna for type 1 diabetes mellitus
Evidence review
Overview
No clinical trial has examined sauna as a therapy for type 1 diabetes. Two small Finnish studies in insulin-treated patients measured how sauna affects absorption of injected insulin. Sauna more than doubled the absorption rate of rapid-acting insulin and lowered blood glucose by about 54-59 mg/dL compared with a control day, whereas it did not change absorption of an intermediate-acting insulin. The evidence therefore concerns hypoglycemia risk rather than benefit.
Key findings
- Rapid-acting insulin: sauna (2 x 25 min at 185 F) accelerated absorption from the injection site by 110% (p<0.01) and lowered blood glucose by 3.0-3.3 mmol/L (54-59 mg/dL) vs a control day (p<0.05), n=8 (Koivisto 1980).
- Intermediate-acting (amorphous) insulin: the same sauna protocol did not significantly change absorption or blood glucose, n=8 (Koivisto 1983).
Every study we reviewed
1 found harm · 1 found no effect
Each study was checked on PubMed. The colored edge shows the direction of the result.
Sauna-induced acceleration in insulin absorption from subcutaneous injection site.
Koivisto VA et al. Br Med J. 1980. PubMed 7000239 · DOI · Free full text
- Who
- Insulin-dependent diabetic patients
- What
- Finnish sauna after subcutaneous injection of 125I-labelled rapid-acting insulin vs room-temperature control day
- Protocol
- 185 °F · 25 (x2) min · single session/wk
- Measured
- Insulin absorption rate (external counting of labelled insulin); blood glucose
- Result
- Insulin absorption accelerated by 110% vs room temperature (p<0.01); blood glucose 3.0-3.3 mmol/L (54.1-59.5 mg/dL) lower than on the control day (p<0.05); glucose fall proportional to absorption rate (r=0.30; p<0.01).
- Limitations
- Very small; single session; pharmacokinetic study, not a therapeutic trial; older insulin formulations.
Influence of heat on insulin absorption: different effects on amorphous and soluble insulins.
Koivisto VA et al. Acta Diabetol Lat. 1983. PubMed 6349204 · DOI
- Who
- Patients with type 1 diabetes
- What
- Finnish sauna after subcutaneous injection of 125I-labelled intermediate-acting (amorphous) insulin vs control day at 72 F (22 C)
- Protocol
- 185 °F · 25 (x2) min · single session/wk
- Measured
- Insulin absorption rate; blood glucose
- Result
- Sauna did not significantly stimulate absorption of intermediate-acting insulin or lower blood glucose compared with the control day.
- Limitations
- Very small; single session; older insulin formulation; numbers not given in abstract.
Protocols used in the studies
Both studies used a traditional Finnish sauna at 185 F (85 C) for two 25-min periods after a subcutaneous insulin injection, compared with a control day at room temperature (72 F, 22 C).
What is still unknown
Effect of sauna on absorption of modern rapid-acting analogues and pump-delivered insulin; glucose patterns during and after sauna measured by continuous glucose monitoring; whether repeated sauna has any cardiovascular or metabolic benefit in type 1 diabetes.
Safety
Cautions for sauna in this condition
- Sauna accelerated absorption of rapid-acting insulin by 110% and lowered blood glucose by 54-59 mg/dL (PMID 7000239); the authors suggested a snack or reduced insulin dose to prevent hypoglycemia.
- The effect depended on insulin type: no significant change with an intermediate-acting insulin (PMID 6349204). Neither study examined modern insulin analogues or insulin pumps.
- Diabetic neuropathy increases burn risk; a second-degree burn occurred in a patient with advanced diabetic neuropathy using a portable sauna (PMID 36203760).
For clinicians
Suggested rationale
There is no published evidence that sauna treats type 1 diabetes; the available patient data show that sauna can accelerate absorption of rapid-acting insulin and lower blood glucose (Koivisto 1980), so any use for another indication calls for glucose monitoring and insulin or carbohydrate adjustment.
Suggested wording only. The treating clinician decides whether it reflects their clinical judgment for this patient.
Typical ICD-10 codes: E10.9, E10.649. Examples only; the clinician assigns the code.
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