Small Intestinal Ketogenesis - Potential Significance for Type 2 Diabetes in Obesity
Phase: NA
Conditions: Obesity, Morbid, Diabetes Mellitus, Type 2, Intestines, Incretins
Sponsor: Göteborg University

 
1 
Small intes+nal ketogenesis – poten+al signiﬁcance for type 2 diabetes in obesity 
 
Professor Lars Fändriks et al, University of Gothenburg, Sweden  
 
 
NCT05767177 
 
Date: 02/09/2023 (translated) 
 
 
 

 
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Small intes+nal ketogenesis – poten+al signiﬁcance for type 2 diabetes in obesity 
 
Professor Lars Fändriks et al, University of Gothenburg, Sweden  
 
 
 
Overall scien,ﬁc ques,on: 
Do obesity cause disturbances in intes0nal food-induced ketogenesis and does this inﬂuence the 
development of type 2 diabetes mellitus? 
 
Speciﬁc issues: 
1. Does food intake-induced ketogenesis exist in the small intes0ne of obese individuals? 
2. Are insulin resistance, GLP-1 release and SGLT1 aﬀected in obese individuals without type 2 
diabetes in the same way as those with type 2 diabetes? 
3. If no to 2: Where is the diﬀerence? 
 
 
 
Area overview 
Obesity (obesitas) has increased drama0cally in the last 3 decades. Obesity also comes with diseases, 
including type 2 diabetes, high blood pressure and changes in lipid status. It is now common 
knowledge that obesity with type 2 diabetes can be treated with a certain type of gastrointes0nal 
surgery, the best known being gastric bypass surgery. This opera0on means that the food ends up 
directly in the small intes0ne and has long been used for weight-reducing purposes. The fact that this 
opera0on, in addi0on to its eﬀect on body weight, also has a good eﬀect on diabetes has been 
no0ced in recent years. Of course, there are also treatment failures and side eﬀects, including 
micronutrient deﬁciency, linked to this surgery. But on the whole, gastric bypass brings a longlas0ng 
weight loss and in most cases also relief of the co-morbidity, e.g. diabetes type 2. A prerequisite, 
however, is that you take life-long subs0tu0on of micronutrients (calcium, iron, vitamin C and D etc.).  
 
Gastric bypass eﬀect on obesity and type 2 diabetes. Gastric bypass provides a powerful and long-
las0ng reduc0on in body weight. The opera0on also improves type 2 diabetes, in most cases 
immediately aTer the opera0on, i.e. before the body weight has been aﬀected. (Wolfe et al 2016) 
This suggests that the altered gastrointes0nal anatomy has a direct eﬀect on blood glucose 
regula0on. The mechanisms are not fully known and include reduced secre0on of certain 
gastrointes0nal hormones (for example GLP-1; used in some modern diabetes drugs such as 
liraglu0de and semaglu0de) in a posi0ve way. Furthermore, the distribu0on and composi0on of the 
intes0nal microorganisms changes. The opera0on thus ac0vates several diﬀerent mechanisms that 
probably work together. However, there is no complete physiological explana0on for why this surgery 
improves the diabetes disease. 
 
Ketone bodies during fas0ng/starva0on. This project-plan deals with ketone bodies, ie mainly the 
substances beta-hydroxybutyrate and acetoacetate. Acetone is also represented, but is a gas-soluble 
factor that mainly ends up in the exhaled air and thus leaves the body. Ketone bodies are normally 
formed in the liver during fas0ng/starva0on when the body's blood sugar level becomes very low. In 
this situa0on, ketone bodies take over as an energy source in the blood and the produc0on does not 
decrease un0l the blood sugar is back to the original levels. It is well known that systemically 
increased levels of ketone bodies (measured in peripheral venous return) have been shown to aﬀect 
diabetes disease, some0mes lethally through ketoacidosis. One way to physiologically increase the 
body's ketone bodies is through a ketogenic diet (essen0ally a high-fat diet with a reduced number of 

 
3 
calories). NOTE: We are careful not to confuse these systemic phenomena with the gut-produced 
ketone bodies (see below). 
 
Intes0nally produced ketone bodies. It has been shown that the mucosa in the middle small intes0ne, 
the jejunum, changes rela0vely quickly so that intake of fa`y food causes the mucosa to produce 
ketone bodies. This is thus contrary to the common view, according to above, that ketone bodies are 
formed during fas0ng/starva0on. The intes0nally produced ketone bodies end up in the portal vein, 
i.e. the blood drainage that goes directly to the liver. There it is diluted with blood from other organs, 
which is why you see a moderate or no increase in a blood sample taken in a peripheral vein. What 
then do jejunal ketone bodies in the portal vein? We have recently described that gastric bypass 
reduces the ability of the jejunum to manufacture "ketone bodies". This releases a brake on the 
produc0on of GLP-1 (Wallenius et al 2020). This is probably because gastric bypass surgery individuals 
drama0cally reduce their intake of fat in favor of (slow) carbohydrates. 
 
 
 
Hypothesis 
Our hypothesis (par0ally proven) is that the local ketone body forma0on (ketogenesis) inhibits the 
release of the hormone GLP-1. This hormone is released from the intes0ne into the blood in the 
portal vein, via the liver and on to all the body's cells. GLP-1 controls, among other things, insulin 
sensi0vity (a very important factor in type 2 diabetes) and is an important factor in slowing down 
food intake. Furthermore, parallel to this, there is a brake on the expression of the enzyme that 
absorbs glucose across the mucosa (SGLT1). The local ketogenesis in the intes0nal mucosa thus slows 
down 2 factors of par0cular importance for glucose homeostasis: partly GLP-1 mediated insulin 
sensi0vity in general in the body, partly the SGLT1 mediated glucose transport across the mucosa. 
Recently, we demonstrated in healthy volunteers that this fat-induced ketone body forma0on de-
facto exists. We also found clear signs of disturbances in glucose uptake in the intes0ne, but at the 
systemic level the values were adequate (Wallenius et al 2021, Elebring et al 2022). The ques0on in 
the present project is: What does intes0nal ketogenesis look like in individuals with obesity? Are 
there changes that contribute to the development of, among other things, type 2 diabetes mellitus 
(see above)? 
 
 
 
Project descrip4on 
 
Summary 
Human subjects, either without or with non-insulin-treated diabetes type 2 + possibly with any other 
metabolic disorder (see below). Otherwise, the individuals must be medica0on-free (excep0ons may 
be allowed) and physically mobile. Pa0ents with insulin-treated diabetes are avoided so that they are 
not exposed to any risks (especially hypoglycemia). Par0cipants in this study receive two complete 
diets for 2 weeks each from the laboratory. The diet is put together by a die00an specializing in 
obesity/diabetes and is individual. In one case the diet is of the type "high-carbohydrate diet" and in 
the other case "high-fat diet". The idea is that the research subjects should subsist on these diets for 
the respec0ve 14 days. The energy content of the diet periods must be the same and correspond to 
the par0cipants' daily needs. Each par0cipant take one diet for 2 weeks. ATer a break of at least 3 
weeks, the second diet is taken for 2 weeks. In each diet, a meal test is done aTer 12 days and aTer 
the 14th day an enteroscopy with a sample of the intes0nal mucosa. In addi0on to this, blood 
samples and ques0onnaires are taken to describe the general state of health and gastroenterological 
status. This is an exploratory study, which is why the number of research subjects is limited to 20 
individuals. 
 

 
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Research persons 
Research is carried out on 20 obese individuals who are metabolically healthy (approx. 10/20) or have 
type 2 diabetes (co-morbidi0es such as high blood pressure, blood lipid disorders and the like are 
accepted if they have been stabilized >1 month with adequate pharmacology). All study par0cipa0on 
is voluntary. We par0cipate in the Regional Obesity Center at Sahlgrenska University Hospital. We 
thus come into contact with all obese pa0ents from the Västra Götaland region who are referred for 
treatment. Some of these are contacted by phone by a research nurse to provide further informa0on. 
The research nurse then asks the pa0ent about interest in par0cipa0on. If the answer is yes, the 
pa0ent is called to a physical mee0ng with a blood sample and a die00an. Study physicians assess 
presump0ve par0cipants' condi0ons to par0cipate and, aTer receiving a wri`en response to the 
researcher's request, place suitable candidates on the study list. 
 
Inclusion criteria: 
• Individuals with obesity 
• Age between 18 and 65 
• BMI 35 – 45 kg/m2 without or with type 2 diabetes 
 
Exclusion criteria: 
• Insulin-treated diabetes 
• Sequelae of previous diabetes-associated disease (foot, eyes and kidneys, or cardiovascular 
incident, etc.) 
• Diabetes, hypertension, lipid disorder that has not been stabilized for at least 1 month by adequate 
pharmacological treatment 
• Con0nuous NSAID use 
• Preferably otherwise medica0on-free (excep0ons can be made) 
• Not operated on in the abdomen (appendectomy excluded) 
• Previously known organic gastrointes0nal disease, except for gastroesophageal reﬂux disease 
(GERD) 
• Smokers 
• Pregnancy and breaspeeding 
• History of drug abuse or other circumstances deemed to jeopardize the pa0ent's ability to 
par0cipate in the research project 
 
 
 
 
 
Figure 1. Study overview with visits 1 to 6. 
 
 
 

 
5 
Visit 1: The research person meets a research nurse and a die0cian 
Review of ea0ng habits and physical ac0vity. In addi0on, height + weight is measured and the 
research subject may provide blood and urine samples corresponding to a general health check (Hb, 
glucose/insulin, salt balance, blood fats, liver and inﬂamma0on markers and glucose/protein in 
urine). Blood amount max 20 ml, 0me required 1 hour. Health status and possibly medicines are 
assessed by study doctors who put presump0ve subjects on the study list. 
The research subject is provided with food for two 14-day periods with the same energy content as 
the research subject normally consumes, but where the main energy source is either fat (60% of total 
energy intake, 20% is carbohydrate-based) or carbohydrate (60% of total energy, 20% is fat-based), in 
random order. The goal is for the individual to maintain the weight during the study period. The 
individual diet is constructed by a die0cian with a specialty in obesity/diabetes. The research subjects 
receive ready-made food for one week at a 0me. During the respec0ve diet period, the research 
subject must not use alcoholic beverages, but otherwise live a normal life. ATer diet period 1, the 
research subject must have a 3-week "washout" period. 
 
Visit 2 + 4: On day 12 of each diet, a meal test (Mixed Meal Test) is performed 
Ev. morning medica0ons are taken 45-60 minutes before the laboratory visit. The research person 
arrives at the laboratory at 8.30 a.m., otherwise fas0ng. A venous catheter is placed in one arm 
crease for blood sampling and the research person must answer ques0ons about any gastrointes0nal 
complaints in connec0on with the current diet (GSRS ques0onnaire). At approximately 09:00, the 
research subject may eat a brunch for approximately 15 minutes (sandwich, juice, fried egg and 
sausage; 550-600kcal). Venous blood samples are taken before and 15, 30, 45, 60, 90 and 120 
minutes aTer the meal. At each sampling occasion, the research person has to es0mate hunger or 
sa0ety on a visual analogue scale. The research person may then leave the laboratory and eat their 
regular lunch at 12 to 1pm. 
Analyses: At each blood sampling, the concentra0on of glucose, ketone bodies, insulin and other 
intes0nal hormones in the metabolic control (e.g. glucagon, GIP, GLP-1, PYY etc.) are analyzed and 
possibly presence of intes0nal bacterial components (endotoxinaemia). The examina0on takes 
approximately 2.5 to 3 hours in total. In total, a maximum of 70 ml of blood is taken per diet period 
(which corresponds to a total of 1/6 of a normal blood dona0on). 
 
Visit 3 + 5: On day 14 of each diet period, an enteroscopy is performed with mucosal sampling. This 
step is performed to obtain a sample (biopsy) of the mucosa of the small intes0ne (duodenum and 
jejunum) and is performed at GEA SU-Sahlgrenska or SU-Östra. The research subject arrives at the 
hospital aTer 6-8 hours of fas0ng (morning medica0ons are taken aTer the examina0on). Endoscopy 
is experienced by some individuals as unpleasant, which is why local anesthesia and some0mes 
seda0on (midazolam + pethidine or rapifen) can be oﬀered according to standard rou0ne in the 
endoscopy department. Approximately 8 - 12 biopsies are taken at each loca0on. The responsible 
endoscopist assesses in each individual case whether 0ssue sampling is possible from a medical point 
of view. All 0ssue collec0on is thus done according to clinical rou0ne. Research staﬀ a`end the 
examina0on and take care of the biopsy material which is either ﬁxed, deep-frozen (histology and 
immunoﬂuorescence on given factors such as SGLT1, GRPr, etc) and/or stored for a short 0me in 
oxygenated preserva0on medium (the la`er for func0onal studies on SGLT1 in-vitro i.e. Ussing 
chamber). Gastroenteroscopy is normally carried out in approximately 15-25 minutes. With 
prepara0on 0me, the length of stay in the endoscopy department is approximately 1 hour. 
 
Visit 6. The research subject's health is checked by phone call. 
 
 
 
 
 

 
6 
Preliminary results 
We have shown that jejunal ketone body forma0on can reduce the release of GLP-1 and thus 
interfere with insulin sensi0vity in a manner similar to type 2 diabetes. (Wallenius et al 2019). We 
have also conducted studies on 16 healthy volunteers with basically the same protocol as in the 
current study. It was carried out without any complaints, except that 1 woman had to cancel due to 
an unplanned pregnancy. We then showed that (nb in healthy normal weight people) there is a 
ketone body forma0on from the intes0ne aTer a fa`y meal. We also found clear signs of disturbances 
in glucose uptake in the intes0ne, but at the systemic level the values were normal (Wallenius et al 
2021, Elebring et al 2022). 
 
 
 
Signiﬁcance 
If ketone body forma0on is important for obesity with type 2 diabetes, then the results can be used 
to understand the disease and possibly develop a non-injec0on-dependent pharmacological therapy. 
 
 
 
 
References 
 
Casselbrant A, Wallenius V, Elebring E, Marschall HU, Johansson BR, Helander HF, Fändriks L. 
Morphological Adapta0on in the Jejunal Mucosa aTer Iso-Caloric High-Fat versus High-Carbohydrate 
Diets in Healthy Volunteers: Data from a Randomized Crossover Study. Nutrients. 2022 Oct 
4;14(19):4123. doi: 10.3390/nu14194123. 
 
Elebring E, Wallenius V, Casselbrant A, Docherty NG, Roux CWL, Marschall HU, Fändriks L. A Fa`y Diet 
Induces a Jejunal Ketogenesis Which Inhibits Local SGLT1-Based Glucose Transport via an Acetyla0on 
Mechanism-Results from a Randomized Cross-Over Study between Iso-Caloric High-Fat versus High-
Carbohydrate Diets in Healthy Volunteers. Nutrients. 2022 May 7;14(9):1961. doi: 
10.3390/nu14091961. 
 
Wallenius V, Elebring E, Casselbrant A, Laurenius A, le Roux CW, Docherty NG, Biörserud C, Björnfot N, 
Engström M, Marschall HU, Fändriks L. Glycemic Control and Metabolic Adapta0on in Response to 
High-Fat versus High-Carbohydrate Diets -Data from a Randomized Cross-Over Study in Healthy 
Subjects. Nutrients. 2021 Sep 23;13(10):3322. doi: 10.3390/nu13103322. 
 
Wallenius V, Elias E, Elebring E, Haisma B, Casselbrant A, Larrauﬁe P, Spak E, Reimann F, le Roux CW, 
Docherty NG, Gribble FM, Fändriks L. Suppression of enteroendocrine cell glucagon-like pep0de 
(GLP)-1 release by fat-induced small intes0nal ketogenesis: a mechanism targeted by Roux-en-Y 
gastric bypass surgery but not by preopera0ve very-low-calorie diet. Gut. 2020 Aug;69(8):1423-1431. 
doi: 10.1136/gutjnl-2019-319372. 
 
Wolfe BM, Kvach E, Eckel RH. Treatment of Obesity: Weight Loss and Bariatric Surgery. Circ Res. 2016 
May 27;118(11):1844-55. doi: 10.1161/CIRCRESAHA.116.307591.