Analysis of factors influencing nitrogen balance during acute starvation in obese subject with and without type 2 diabetes.
OBJECTIVE
Patients with type 2 diabetes (T2DM) tend to loose more lean body mass during both long-term weight reduction and short-term very-low-calorie diet. We ask what factors influence protein loss during acute starvation in T2DM.


METHODS
In a prospective in-hospital observational study, we compared 10 subjects with T2DM and 10 age-weight-sex matched obese controls (OB) during 60 h of fasting and used frequent blood sampling and indirect calorimetry to describe metabolic and endocrine response. We analyzed factors influencing nitrogen balance using stepwise multiple regressions.


RESULTS
Despite comparable pattern of plasma insulin, free fatty acid, 3-hydroxybutyrate and almost identical behavior of growth hormone axis, our T2DM subjects remained hyperglycaemic and in contrast to OB subjects they failed to reduce the rate of protein oxidation, even though muscle protein breakdown rate declined similarly in both groups. Regression analysis revealed that protein oxidation rate in T2DM group was enhanced by hyperglycemia and sympathetic activity and suppressed by circulating insulin and 3-hydroxybutyrate. Liver insulin resistance increases peripheral insulin concentrations and enhances the conversion of non-esterified fatty acids (NEFA) to ketones and thus it might be a protein-saving factor.


CONCLUSIONS
Relative deficiency of circulating insulin and hyperglycemia play a pivotal role in the impairment of protein sparing in T2DM during a short-term fasting.
Duska
Frantisek
F
Department of Internal Medicine II, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic. fduska@yahoo.com
Tůma
Petr
P
Mokrejs
Pavel
P
Kubena
Ales
A
Andel
Michal
M
D020155:3-Hydroxybutyric Acid / Q000097:blood; D000273:Adipose Tissue / Q000378:metabolism; D019540:Area Under Curve; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D002153:Calorimetry, Indirect; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy / Q000378:metabolism*; D005215:Fasting / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism; D007328:Insulin / Q000097:blood / Q000172:deficiency*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009765:Obesity / Q000178:diet therapy / Q000378:metabolism*; D011446:Prospective Studies; D012044:Regression Analysis
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D009584:Nitrogen; D020155:3-Hydroxybutyric Acid