Alterations in glucose metabolism in the elderly patient with diabetes.
OBJECTIVE
To determine the alterations in glucose metabolism in elderly patients with NIDDM.


METHODS
We studied 9 healthy elderly control subjects (73 +/- 1 yr of age; body mass index 25.7 +/- 0.4 kg/m2) and 9 untreated elderly NIDDM patients (72 +/- 2 yr of age; BMI 25.9 +/- 0.5 kg/m2). Each subject underwent a 3-h oral glucose tolerance test (40 g/m2); a 2-h hyperglycemic glucose clamp study (glucose 5.4 mM above basal); and a 4-h euglycemic insulin clamp (40 mM.m2.min-1). Tritiated glucose methodology was used to measure glucose production and disposal rates during the euglycemic clamp.


RESULTS
Patients with NIDDM had a higher fasting glucose (9.3 +/- 0.3 vs. 5.1 +/- 0.1 mM in control subjects vs. NIDDM patients, respectively, P < 0.001) and a greater area under the curve for glucose during the OGTT (16.0 +/- 0.6 vs. 6.7 +/- 0.3 mM in control subjects vs. NIDDM patients, respectively, P < 0.01) than the healthy control subjects. During the hyperglycemic clamp, patients with NIDDM had an absent first-phase insulin response (112 +/- 6 vs. 250 +/- 31 pM in control subjects vs. NIDDM patients, respectively, P < 0.01), and a blunted second-phase insulin response (159 +/- 11 vs. 337 +/- 46 pM in control subjects vs. NIDDM patients, respectively, P < 0.01). Before the euglycemic clamp, fasting insulin (99 +/- 5 vs. 111 +/- 10 pM in control subjects vs. NIDDM patients, respectively) and hepatic glucose production (11.8 +/- 0.7 vs. 11.5 +/- 0.5 mumol.kg-1-min-1 in control subjects vs. NIDDM patients, respectively) were similar. Steady-state (180-240 min) glucose disposal rates during the euglycemic clamp were slightly, but not significantly, higher in the normal control subjects (36.5 +/- 1.1 vs. 33.1 +/- 1.9 mumol.kg-1-min-1 in control subjects vs. NIDDM patients, respectively, NS).


CONCLUSIONS
We conclude that NIDDM in nonobese elderly subjects is characterized by a marked impairment in insulin release. This may be attributable to the toxic effects of chronic hyperglycemia on the beta-cell. When compared with age-matched control subjects, the NIDDM patients showed no increase in fasting insulin or hepatic glucose production, and insulin resistance was mild.
Meneilly
G S
GS
Department of Medicine, University of British Columbia, Vancouver, Canada.
Dawson
K
K
Tessier
D
D
D000368:Aged; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D001794:Blood Pressure; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000378:metabolism*; D005260:Female; D005947:Glucose / Q000378:metabolism*; D015309:Glucose Clamp Technique; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007328:Insulin / Q000097:blood / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D012016:Reference Values
D001786:Blood Glucose; D005947:Glucose; D006442:Glycated Hemoglobin; D007328:Insulin