A woman with slowly progressive type 1 diabetes developed severe edema and 7 kg of weight gain after starting insulin therapy, which resolved within nine days by adjusting her insulin regimen and limiting dietary salt.
~7 kg weight gainFluid retention after starting basal-bolus insulin therapy, resolved within 9 days with regimen adjustment
What the researchers found
A patient with slowly progressive type 1 diabetes mellitus (SPIDDM) developed bilateral lower-leg edema and approximately 7 kg of weight gain shortly after starting basal-bolus insulin therapy with insulin aspart and insulin degludec. Cardiac function was normal on echocardiography and B-type natriuretic peptide levels were within the reference range, ruling out heart failure.
The edema resolved rapidly within nine days following modification of the insulin regimen and dietary sodium restriction to 8 g/day of salt, without requiring diuretics. The improvement likely reflected the combined effects of glycemic stabilization, fluid-electrolyte balance, and possible formulation-related factors rather than a direct difference between insulin types.
Why it matters
Insulin edema is rare and often unrecognized, which can lead to unnecessary diagnostic workups or inappropriate treatment. This case demonstrates that even patients with slowly progressive type 1 diabetes — not just those with new-onset or poorly controlled disease — can develop this complication. Recognizing insulin edema early allows clinicians to manage it conservatively through regimen adjustment and salt restriction rather than resorting to diuretics or discontinuing essential insulin therapy.
How the study worked
This is a clinical case report of a single patient. The patient was evaluated with echocardiography and B-type natriuretic peptide testing to exclude cardiac causes. Management involved adjusting the insulin regimen (from insulin aspart and insulin degludec) and implementing dietary sodium restriction. The clinical course was documented over the treatment period.
What this study cannot tell us
As a single case report, this provides no data on incidence, prevalence, or generalizable treatment outcomes. The mechanism of improvement could not be definitively attributed to insulin regimen adjustment versus sodium restriction versus natural resolution. The historical incidence figure (3.5%) comes from a single older study from Africa and may not be generalizable. No controlled comparison of insulin formulations was possible.
How to read the evidence
This is a single case report — the lowest level of clinical evidence. It demonstrates that insulin edema can occur in SPIDDM but cannot establish causation, incidence, or optimal management strategies.
When this study was published
Published in 2026, this is a very recent case report that adds to the sparse literature on insulin edema, particularly in the context of slowly progressive type 1 diabetes and modern insulin analogs.
The bigger picture
As insulin — a peptide hormone — remains the cornerstone treatment for type 1 diabetes and advanced type 2 diabetes, understanding its uncommon side effects is clinically important. Insulin edema sits at the intersection of peptide pharmacology and fluid-electrolyte physiology, involving insulin-mediated sodium retention and potential effects on the renin-angiotensin-aldosterone system. Awareness of this complication becomes increasingly relevant as newer insulin analogs and formulations expand treatment options.
Questions still open
- Does the choice of insulin analog or formulation influence the risk of developing insulin edema?
- What is the true incidence of insulin edema in modern insulin-treated populations across different diabetes subtypes?
- Could routine sodium restriction at insulin initiation prevent edema in susceptible patients?
Common questions
What is insulin edema and how common is it?
How is insulin edema treated?
Read the original research
Insulin edema in slowly progressive type 1 diabetes: improvement following adjustment of insulin therapy.
Diabetology international, 17(1), 13
Citation
Okamura, Emi; Harada, Norio; Okuno, Kana; Yamamoto, Kana; Murakami, Takaaki; Ueda, Yohei; Yabe, Daisuke. (2026). Insulin edema in slowly progressive type 1 diabetes: improvement following adjustment of insulin therapy.. Diabetology international, 17(1), 13. https://doi.org/10.1007/s13340-025-00864-4