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Effect of ageing and diabetes on glucose‐dependent insulinotropic polypeptide and dipeptidyl peptidase IV responses to oral glucose
Author(s) -
Meneilly G. S.,
Demuth H. U.,
McIntosh C. H. S.,
Pederson R. A.
Publication year - 2000
Publication title -
diabetic medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.474
H-Index - 145
eISSN - 1464-5491
pISSN - 0742-3071
DOI - 10.1046/j.1464-5491.2000.00236.x
Subject(s) - medicine , diabetes mellitus , endocrinology , ageing , dipeptidyl peptidase , insulin , body mass index , type 2 diabetes , middle age , enzyme , biochemistry , chemistry
Summary Aims Glucose‐dependent insulinotropic polypeptide (GIP) acts on the pancreas to potentiate glucose‐induced insulin secretion (enteroinsular axis). GIP is rapidly inactivated in vivo by the enzyme dipeptidyl dipeptidase IV (DPP‐IV). The current studies were designed to examine the effect of ageing, obesity and diabetes on GIP and DPP‐IV responses to oral glucose. Methods Healthy controls (nine middle‐aged, age 42 ± 2 years, body mass index (BMI) 33 ± 1 kg/m 2 ; nine elderly, age 71 ± 1 years, BMI 30 ± 1 kg/m 2 ) and patients with Type 2 diabetes (12 middle‐aged, age 44 ± 2 years, BMI 34 ± 2 kg/m 2 ; 19 elderly, age 74 ± 1 years, BMI 31 ± 1 kg/m 2 ) underwent a 3‐h oral glucose tolerance test (OGTT) (glucose dose 40 g/m 2 ). Results Insulin responses were similar in elderly controls and patients with diabetes, but were lower in middle‐aged patients with diabetes than in controls (308 ± 65 vs. 640 ± 109 p M , P < 0.05). GIP responses were similar in controls and patients with diabetes in each age group, but were higher in elderly controls (middle‐aged 45 ± 13; elderly 112 ± 13 p M , P < 0.01) and patients with diabetes (middle‐aged 55 ± 10; elderly 99 ± 10 p M , P < 0.01). DPP‐IV levels were lower in patients with diabetes in both middle‐aged (control 0.241 ± 0.015; diabetes 0.179 ± 0.017 ΔOD/20 min, P < 0.05) and elderly groups (control 0.223 ± 0.019; diabetes 0.173 ± 0.010 ΔOD/20 min, P < 0.05). Conclusions It was concluded that ageing in obese subjects is associated with enhanced GIP responses to oral glucose. In addition, DPP‐IV activity is reduced in middle‐aged and elderly obese patients with diabetes.