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What happens to muscle energy when insulin is withheld in type 1 diabetes
Effect of insulin deprivation on muscle mitochondrial ATP production and gene transcript levels in type 1 diabetic subjects.
Overview
Karakelides H et al.. Diabetes 2007 · PMID 17660267 · DOI 10.2337/db07-0378
Stopping insulin for about 9 hours reduced the muscle cells' energy (ATP) production and raised ketones and protein breakdown.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Test how insulin lack affects muscle energy production.
- How was the study done?
Insulin withdrawal vs insulin, muscle biopsies.
- How many people, animals or samples were studied?
9 adults with T1D.
- What was actually found?
Less mitochondrial ATP production, more ketones and protein loss without insulin.
- How large was the observed effect?
Not given in abstract.
- What do the results mean in everyday life?
Insulin keeps the cell's energy engine running; lack of insulin slows it.
- What are the study's limitations?
Very small study.
- What does it say about Elawady's specific claim?
Contradicts 'insulin stops the Krebs cycle'.
- Do the results apply to Germany and Europe?
Universal physiology.
- What can explicitly not be concluded from this study?
Cannot quantify long-term effects.
Scientific in-depth review
1. Full reference
- Authors
- Karakelides H et al.
- Journal
- Diabetes
- Year
- 2007
- Identifier
- PMID 17660267 DOI 10.2337/db07-0378
- Verification
- verified – PubMed efetch 2026-10-26; Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH and non-US government support (record).
2. Research question
What does insulin deficiency do to muscle mitochondrial ATP production in T1D?
3. Study design and population
- Study design
- Other – Experimental crossover physiology study (insulin withdrawal vs insulin-treated state) with muscle biopsies
- Population
C-peptide-negative adults with T1D
- Country
USA (Mayo Clinic)
- Period
Not stated in abstract
- Sample size
9
- Inclusion and exclusion criteria
C-peptide-negative T1D
4. Methods and endpoints
- Exposure / intervention
Insulin withdrawal for 8.6 +/- 0.6 h
- Comparator
Insulin-treated state (same individuals)
- Endpoints
Muscle mitochondrial ATP production rate, gene transcripts, oxygen consumption, substrates
- Statistical methods
Paired comparisons
5. Actual results
- Results
Insulin withdrawal increased glucose, branched-chain amino acids, NEFA, beta-hydroxybutyrate and urinary nitrogen; it decreased muscle mitochondrial ATP production and transcripts of oxidative phosphorylation genes despite higher whole-body oxygen consumption.
- Absolute risks
not reported
- Authors' conclusion
Insulin deficiency reduces muscle mitochondrial ATP production and oxidative phosphorylation gene expression in T1D.
6. Strengths
- Direct human experiment
- Paired design
7. Weaknesses
- Small (n=9)
- Short deprivation
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Small mechanistic study.
9. Assessment of the statistical interpretation
Direction of effect clear; magnitudes not given in abstract.
10. Relevance to the specific claim
Opposite of the claim: it is the absence of insulin, not insulin, that impairs mitochondrial ATP production (Krebs cycle/oxidative phosphorylation) and increases protein breakdown (urinary nitrogen) and ketones.
11. Independent contrary findings
12. Transferability to Germany and Europe
Directly applicable; same biology and clinical standards in Europe.
13. Overall methodological judgement
Direct human evidence against 'insulin halts the Krebs cycle'.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | low |
| Directness | direct |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Injected insulin halts the Krebs cycle, blocks protein and DNA synthesis, starves the brain of glucose and causes seizures and blood clots. – Studies contradicting or limiting the claim
- Insulin is not needed for glucose to enter cells (the HbA1c inside red blood cells proves it); insulin therefore does not treat diabetes but 'starves' cells, especially the brain, of sugar. – Studies contradicting or limiting the claim