Summary
In the present study we measured the activity of some cytosolic enzymes involved in
intracellular glucose metabolism in mononuclear leukocytes from 77 obese subjects
of which 39 were nondiabetic and 38 had newly-diagnosed untreated type II diabetes
mellitus. 28 subjects (19 nondiabetic and 18 diabetic) had also a study of insulin
binding to monocytes. 35 subjects (14 nondiabetic, 21 diabetic) underwent an insulin
tolerance test for the evaluation of in vivo insulin action. Mononuclear leukocytes
from diabetic obese patients showed significantly lower activities of hexokinase (HK),
6-phosphofructokinase (PFK) and glucose-6-phosphate dehydrogenase (G6PDH), while pyruvate
kinase (PK) and 6-phosphogluconate dehydrogenase (6PGDH) activities were similar in
the two groups. In the whole population HK and G6PDH activities inversely correlated
with fasting and 2-h OGTT plasma glucose levels. Neither plasma insulin levels nor
maximal specific insulin binding to monocytes were significantly correlated with any
of the enzyme activities measured. Conversely, the parameter of insulin action generated
by insulin tolerance test significantly correlated with HK, G6PDH and 6PGDH. These
results indicate that in obese subjects the presence of diabetes is associated with
a reduced activity of some enzymes of glucose metabolism in mononuclear leukocytes.
This multiple enzymatic defect is correlated with the impairment of in vivo insulin
action.
Key words
Obesity - Diabetes Mellitus - Mononuclear Leukocytes - Insulin Action - Enzymes
