Carboxylated and undercarboxylated osteocalcin in metabolic complications of human obesity and prediabetes.
Carboxylated osteocalcin (Gla-OC) participates in bone remodeling, whereas the undercarboxylated form (Glu-OC) takes part in energy metabolism. This study was undertaken to compare the blood levels of Glu-OC and Gla-OC in nonobese, healthy obese, and prediabetic volunteers and correlate it with the metabolic markers of insulin resistance and early markers of inflammation.



Nonobese (body mass index [BMI] <30 kg/m2; n = 34) and obese subjects (30 <BMI <40 kg/m2; n = 98), both sexes, aged 25 to 65 years, were divided into healthy control, normal weight subjects, healthy obese, and obese with biochemical markers of prediabetes. The subgroups with obesity and low or high Gla-OC or Glu-OC were also considered for statistical analysis. After 2 weeks of diet standardization, venous blood was sampled for the determination of Gla-OC, Glu-OC, lipid profile, parameters of inflammation (hsCRP, interleukin 6, sE-selectin, sPECAM-1, and monocyte chemoattractant protein 1), and adipokines (leptin, adiponectin, visfatin, and resistin).



Gla-OC in obese patients was significantly lower compared to nonobese ones (11.36 ± 0.39 vs 12.69 ± 0.90 ng/mL, P = .048) and weakly correlated with hsCRP (r = -0.18, P = .042), visfatin concentration (r = -0.19, P = .033), and BMI (r = -0.17, P = .047). Glu-OC was negatively associated with fasting insulin levels (r = -0.18, P = .049) and reduced in prediabetic individuals compared with healthy obese volunteers (3.04 ± 0.28 vs 4.48 ± 0.57, P = .025).



Decreased blood concentration of Glu-OC may be a selective early symptom of insulin resistance in obesity, whereas the decreased level of Gla-OC seems to be associated with the appearance of early markers of low grade inflammation accompanying obesity.
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Urszula
U
Razny
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Danuta
D
Fedak
Department of Metabolic Diseases, Jagiellonian University Medical College, Krakow, Poland.
Beata
B
Kiec-Wilk
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Joanna
J
Goralska
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Anna
A
Gruca
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Anna
A
Zdzienicka
Department of Endocrinology, Jagiellonian University Medical College, Krakow, Poland.
Malgorzata
M
Kiec-Klimczak
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Bogdan
B
Solnica
Department of Endocrinology, Jagiellonian University Medical College, Krakow, Poland.
Alicja
A
Hubalewska-Dydejczyk
Department of Clinical Biochemistry, Jagiellonian University Medical College, Krakow, Poland.
Malgorzata
0000-0002-3522-0711
M
Malczewska-Malec
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D002264:Carboxylic Acids / Q000737:chemistry*; D004734:Energy Metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000209:etiology*; D007333:Insulin Resistance; D008297:Male; D008659:Metabolic Diseases / Q000097:blood / Q000209:etiology*; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications*; D015675:Osteocalcin / Q000097:blood*; D011236:Prediabetic State / Q000097:blood / Q000150:complications*; D011379:Prognosis
D015415:Biomarkers; D001786:Blood Glucose; D002264:Carboxylic Acids; D015675:Osteocalcin
carboxylated osteocalcin; obesity; prediabetes; undercarboxylated osteocalcin
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