health
Blood Sugar Increase
Adverse effectBlood Sugar Increase is an adverse health outcome in which blood glucose becomes elevated or less well controlled than expected. It describes a change in blood sugar, not a diagnosis or a specific symptom.
See the health context for Blood Sugar Increase in a concise, easy-to-scan format.
These are research findings, not promises. Most options have little evidence, and results differ from person to person.
What can cause it
How likely each one is to cause it, most likely first.
Hot BathpracticePossible
Based on 2 studies. Strongest study: a randomized controlled trial.
In healthy participants, venous glucose was higher during hot-water immersion than control at 15 min, 60 min, and 120 min. In a 2019 trial, glucose incremental area under the curve during the OGTT was higher with hot-water immersion.
Open the Hot Bath pageFastingpracticeUnclear
Based on 2 studies. Strongest study: a pooled analysis of several trials.
A 2023 systematic review of observational studies in people with fatty liver reported increased fasting blood sugar after Ramadan fasting. A 2025 meta-analysis reported 38.87 total events per 100 observations for hypoglycemia, hyperglycemia, and DKA combined, with high heterogeneity; this combined figure is not an estimate of blood sugar increases alone.
Open the Fasting pageStrength TrainingpracticeUnclear
Based on one study. Strongest study: a pooled analysis of several trials.
A 2025 pooled analysis whose study designs were not recorded found an unexpected significant increase in fasting blood glucose within the experimental group, among 13 people in its analysis of this outcome.
Open the Strength Training pageHigh-Intensity Interval Training (HIIT)practiceUnclear
Based on one study. Strongest study: a study that followed people over time.
A cohort of 59 people with obesity found that HbA1c increased after 2 years in HIIT compared with post-intervention.
Open the High-Intensity Interval Training (HIIT) pageCyclingpracticeUnclear
Based on one study. Strongest study: a randomized controlled trial.
A randomized trial of 12 people found that glucose concentrations after the FASTED-PM trial were higher than after all other trials.
Open the Cycling pageInfrared SaunapracticeUnclear
Based on one study. Strongest study: a randomized controlled trial.
Open the Infrared Sauna pageFinnish SaunapracticeUnclear
Based on one study. Strongest study: a randomized controlled trial.
A 1985 randomized trial involving 6 people found a lowered insulin response (P less than 0.001) to a glucose challenge during heating compared with an oral glucose tolerance test under thermoneutral conditions (23 degrees C). This finding describes the insulin response, not a measured increase in blood glucose.
Open the Finnish Sauna page
The expert view shows every study, dose protocol and source.
What can cause it
Interventions reported to bring this on7 listedHighest probability
- →PracticesHot BathCertaintyMediumSourceClinical2 other sources
In healthy participants, venous glucose was higher during hot-water immersion than control at 15 min, 60 min, and 120 min. In a 2019 trial, glucose incremental area under the curve during the OGTT was higher with hot-water immersion (HWI 233 ± 88, CON 156 ± 79 mmol·L^−1·2 h, P = 0.02).
Who was studied
- Healthy people
Open Hot BathStudy result
venous [glucose] was greater during HWI versus CON at 15 min (p = 0.047, g_av = 1.12), 60 min (P = 0.020, g_av = 1.25) and 120 min (P = 0.006, g_av = 1.46)
Low probability(6)
- →PracticesFastingCertaintyLowSourceClinical2 other sources
A 2023 systematic review of observational studies in people with fatty liver reported increased fasting blood sugar after Ramadan fasting. A 2025 meta-analysis reported 38.87 total events per 100 observations for hypoglycemia, hyperglycemia, and DKA combined, with high heterogeneity (I² = 95%); this combined figure is not an estimate of blood sugar increases alone.
Who was studied
- People with a condition
- Fatty Liver Nafld
Open FastingStudy result
The overall pooled effect estimates for the total complications (hypoglycemia, hyperglycemia, and DKA combined) was 38.87 events per 100 observations (95% CI [20.30; 59.20]), with a high degree of heterogeneity (I² = 95%).
- →PracticesStrength TrainingCertaintyLowSourceClinical1 other source
A 2025 pooled analysis whose study designs were not recorded found an unexpected significant increase in fasting blood glucose within the experimental group (p= 0.03), among 13 people in its analysis of this outcome.
Who was studied
- People with a condition
Open Strength TrainingStudy result
an unexpected significant increase in fasting blood glucose levels was found within the experimental group (p= 0.03)
- →PracticesHigh-Intensity Interval Training (HIIT)CertaintyLowSourceClinical1 other source
A cohort of 59 people with obesity found that HbA1c increased after 2 years in HIIT compared with post-intervention (1.3 mmol/mol, 95%CI 0.5 to 2.1, p = .002).
Who was studied
- People with a condition
- Obesity
Open High-Intensity Interval Training (HIIT)Study result
Compared with post-intervention, HbA1c and HDL-cholesterol increased after 2 years in HIIT (1.3 mmol/mol, 95%CI 0.5 to 2.1, p = .002
- →PracticesCyclingCertaintyLowSourceClinical1 other source
A randomized trial of 12 people found that glucose concentrations after the FASTED-PM trial were higher than after all other trials (P < 0.05).
Who was studied
- People with a condition
Open CyclingStudy result
Glucose concentrations were greater in the postprandial period of FASTED-PM compared to all trials (P < 0.05).
- →PracticesInfrared SaunaCertaintyLowSourceClinical1 other source
In a trial involving 12 people with Diabetes Type 2, plasma glucose response during an oral glucose tolerance test was higher after the heated condition than after the thermoneutral condition: 17.7±3.1 versus 14.8±2.8 mmol/L/120 min.
Who was studied
- People with a condition
- Diabetes Type2
Open Infrared SaunaStudy result
The incremental area under the curve (iAUC) of plasma glucose concentrations during the OGTT was higher after the heated condition compared to the thermoneutral condition (17.7±3.1 vs. 14.8±2.8 mmol/L/120 min; P<0.001).
- →PracticesFinnish SaunaCertaintyLowSourceClinical1 other source
A 1985 randomized trial involving 6 people found a lowered insulin response (P less than 0.001) to a glucose challenge during heating compared with an oral glucose tolerance test under thermoneutral conditions (23 degrees C). This finding describes the insulin response, not a measured increase in blood glucose.
Who was studied
- Healthy people
Open Finnish SaunaStudy result
The lowered insulin response (P less than 0.001) to glucose challenge during heating ... were observed, when compared to OGTT under thermoneutral conditions (23 degrees C).
How to read the evidence
Evidence tier — overall strength of the evidence for the whole compound
- StrongWell established — backed by strong, consistent human research.
- ModerateSome genuine support, but mostly from small or lower-quality studies. Promising, not proven.
- PreliminaryEarly-stage evidence — a promising hypothesis, not an established effect yet.
- LimitedVery limited evidence — treat this as a hypothesis, not proof.
- InsufficientNot enough good evidence to draw conclusions yet.
Certainty — how sure we can be that the effect is real
- Very highVery sure — strong, consistent evidence
- HighFairly sure — consistent evidence from good studies
- MediumModerately sure — new studies could change this
- LowNot sure — little or mixed evidence
- Very lowVery unsure — almost no usable evidence
Source — where the data comes from
- Meta-analysisPooled analysis of many trials — the strongest evidence
- RCTRandomized controlled trial — a strong human study design
- ClinicalA human clinical study
- Reference knowledgeFrom general health-science or pharmacology references, not a study of this exact claim
- Animal researchStudied in animals, not humans
- Community reportsAggregated user reports — anecdotal signal, not evidence
- TheoreticalMechanism-based reasoning, not yet tested
Study grade — quality of each underlying study (A best, D weakest)
- AHigh-quality — strong, consistent human trials
- BGood — solid evidence with some limitations
- CModerate — limited, small, or mixed-quality studies
- DWeak — preliminary, indirect, or animal-only
Confidence — how strongly the sources back a finding
A 0–100 score from study quality and agreement
Most supplement evidence is graded C–D. Read it as preliminary signal, not proof.
Full write-up
What is it
Blood Sugar Increase is an adverse health outcome in which blood glucose becomes elevated or less well controlled than expected. It describes a change in blood sugar, not a diagnosis or a specific symptom. This outcome has been reported in connection with interventions including Vitamin B3 (Niacin), Caffeine, Melatonin, and Astragalus.
How interventions help
Reported increases in blood sugar are not presented as one uniform response. The circumstances differ across interventions: some findings involve use alongside food, some involve higher intake, and some are limited to particular metabolic contexts. Melatonin was associated with impaired blood glucose control when consumed with carbohydrate-rich meals, while Cycling was linked to greater postprandial glucose concentrations in the FASTED-PM condition compared with all trials. Glucosamine is generally described as glucose-neutral at usual oral doses, but people with impaired glucose tolerance or insulin resistance may experience worsened glycemic control. Selenium-related concern is associated with high intake rather than routine use.
Vitamin B3 (Niacin) is the clearest example of a longer-duration exposure in the information available: ER niacin 2 g/day plus laropiprant 40 mg/day was taken for a median 3.9 years. In that comparison, 0.9% (119/12,838) developed the outcome versus 0.4% (50/12,835) with placebo, an absolute excess of 0.5% (SE 0.1%), p<0.0001. This illustrates that an increase may emerge during sustained use rather than immediately after a single exposure.
Other reported associations are narrower or less conclusive in practice. Caffeine, Astragalus, Acetyl-L-Carnitine (ALCAR), and Whey Protein have been linked with hyperglycemia or elevated blood sugar, but the reported descriptions do not establish a shared timing pattern. Ashwagandha is represented by a report of new-onset diabetes mellitus, and MCT Oil was mentioned in 2 of 63 Bluesky reports discussing it. The information provided does not establish whether these effects persist after stopping any intervention.
Choosing guidance
These options are not interchangeable evidence-wise. The findings combine controlled clinical research, meta-analyses, a review, a pharmacology reference, a case report, and anecdotal reports. That means the results apply to different levels of certainty and to different study contexts. Cycling, for example, was studied in a clinical-condition setting, so its finding may not translate directly to every person using it. A single case report or anecdotal observation is also less informative about how commonly an effect occurs across users.
The information available does not establish a common onset time or show whether blood sugar changes persist after stopping. It also does not provide enough detail to determine whether studies consistently agree or disagree for most options. Vitamin B3 (Niacin) is the clearest example of a prolonged clinical exposure being evaluated, while several other entries have limited participant or study information. Readers comparing options should therefore consider whether their situation resembles the people or circumstances studied, rather than assuming that all listed effects carry the same relevance. Those with existing concerns about blood sugar may find the clinical context and exposure pattern more useful than an isolated report, a general reference statement, or an anecdotal mention.