Endocrine Abstracts

Introduction: To understand the pathological changes associated with glucose homeostasis in old age, it is necessary to know the natural changes in the processing of proinsulin into mature insulin. Surprisingly, while there is abundant information about insulin function in diabetics, the situation in healthy adults and old humans was rarely examined.

The study aimed: To determine how the proinsulin secretion in individuals with normal glucose tolerance changes during the process of natural aging.

Methods: A total of 761 individuals (539 women, 222 men) with normal glucose tolerance were divided into groups according to age: 1) 18-30 years 355 persons, 2) 30-45 years 234 persons, 3) 45-60 years 103 persons, 4) 60-75 years 58 people, 5) 75-90 years 11 people.Basal blood glucose, proinsulin, insulin, C-peptide levels, HOMA-R, BMI and proinsulin/insulin, proinsulin/C-peptide, proinsulin/glycemia ratios were monitored.Parameters were compared between age groups, separately for women and men. Statgraphics software (Kruskal-Wallis, Dunn’s test, P0.05).

Results: Blood glucose levels increased with age. The age categories up to 30 and up to 45 years had the lowest levels and differed from the older groups. The older categories no longer differed. HOMA-R increased with age and matched the development of BMI in the categories. HOMA-R was highest in women in the 60-75 category and men in the 45-60 category.Basal insulin and C-peptide levels depended on gender. For women, the highest levels were in the category of 60-75 years, for men already in the category of 45-60 years. Proinsulin levels were highest in the youngest women under the age of 30, then decreased with age and the differences were no longer significant. In men, proinsulin levels did not differ with age.The proinsulin/insulin ratio was highest in both sexes under 30 years of age. The proinsulin/glycemia ratio was also highest at age 30, but only in women. The insulin/C-peptide ratio did not change with age.

Conclusion: A cross-sectional analysis of basal proinsulin secretion in normoglycemic individuals showed that its levels were surprisingly highest in the 18-30 age group, especially in young women. The proinsulin/insulin ratio was also highest in the youngest, both sexes. All people, including normoglycemic, develop insulin resistance with age. We showed a slight age-dependent increase in insulin and C-peptide secretion, the peak of which was different in men and women. However, in normoglycemic subjects, proinsulin secretion did not increase with age.AZV-NV18-01-00399, MH-CZ-DRO-(EU00023761)