J Obes Metab Syndr.  2021 Jun;30(2):178-183. 10.7570/jomes20088.

The Shape of the Oral Glucose Tolerance Test-Glucose Response Curve in Islet Cell Antibody-Positive vs. -Negative Obese Youth Clinically Diagnosed with Type 2 Diabetes

• Kim JY
• Tfayli H
• Bacha F
• Arslanian S

• KMID: 2517323
• DOI: http://doi.org/10.7570/jomes20088

Abstract

Background
The oral glucose tolerance test (OGTT)-glucose response curves (GRCs; incessant increase, monophasic, and biphasic) reflect insulin sensitivity and β-cell function, being worse in the former and superior in the latter. Here, we examined if the OGTT-GRC pattern is worse in obese antibody (glutamic acid decarboxylase 65-kDa [GAD65] and insulinoma-associated protein-2 [IA-2])-positive (Ab⁺) vs. –negative (Ab^–) youth clinically diagnosed with type 2 diabetes (CDX-T2D).
Methods
Forty-seven obese youth, 15 Ab⁺ and 32 Ab^– , were divided into three OGTT-GRC groups: incessant increase, monophasic, and biphasic. The prevalence of OGTT-GRC, clamp-measured insulin sensitivity, and β-cell function was compared.
Results
Incessant increase OGTT-GRC is the most frequent curve type and is three-fold higher in Ab⁺ vs. Ab^– youth CDX-T2D. In Ab⁺ youth, there was up to 40% lower second-phase insulin secretion in the incessant increase group vs. the other two groups combined (monophasic and biphasic). In Ab^– youth, while first- and second-phase insulin secretion was significantly lower in the incessant increase vs. the other two groups combined, overall β-cell function was less impaired than in Ab⁺ youth. In neither Ab^– or Ab⁺ youth was OGTT-GRC related to hepatic or peripheral insulin sensitivity.
Conclusion
Severe insulin deficiency, a characteristic of type 1 diabetes, seems to be related to higher prevalence of incessant increase in Ab⁺ vs. Ab^– obese youth.

Keyword

Oral glucose tolerance test; Glucose intolerance; Insulin resistance; Insulin secretion; Type 2 diabetes mellitus; Obesity; Adolescent