Insulin treatment of elderly type 2 diabetic patients

Abstract

In this study, the effect of improved metabolic control through insulin treatment was investigated in elderly patients with type 2 diabetes with secondary failure of oral treatment.

Forty, consecutive, elderly patients (mean age 75.3 (5.9) (mean and SD), range 67-86 years) were studied. They were randomised to insulin treatment (n=22) or to continue using sulfonylurea treatment (n= 18). There was a drop- out of five patients. The remaining patients were re-examined every six months for one year. At the start of the study, the two groups were similar.

In the insulin-treated group, the fasting blood-glucose value fell from 13.8 (2. 1) to 8.9 (2.8) (p<0.001) and 9.7 (1.9) (p<0.001) mmol/L after 6 and 12 months, respectively, using one or two doses of NPH insulin, mean 0.53 (0.24) IU per kilogram of body weight and day. The HbA1c fell from 9.3 (1.4) to 7.2 (0.8) (p<0.00 1) and 7.3 (1.1) (p<0.001)%, but the body weight increased from 73 (14) to 75 (13) (p<0.05) and 76 (14) (p<0.01) kg. In the sulfonylurea- treated group, the fasting blood-glucose value was unchanged, 13.1 (2.3), 12.4 (2.7) and 12.1 (2.2) mmol/L at the start and after 6 and 12 months, respectively. The HbAlc values were 9.1 (1.2), 8.6 (1.4) and 9.3 (1.5)%. The body weight decreased from 78 (15) to 77 (16) and 76 (16) (p<0.05) kg.

In starting insulin treatment, patients paid 5.5 (2.2) visits and made 6.1 (3.8) phone calls for dose adjustments during a total time of 3.1 (0.8) hours and during a period of 48 (19) days. The cost of starting insulin treatment at the health- care centre was SEK 1,107 (at 1995 values), compared with SEK 6,066 at the hospital's day-care clinic. In the insulin-treated patients, the 24-hour, ambulatory blood pressures did not change, in spite of improved metabolic control, probably owing to the counteracting effect of increased body weight Well-being and symptoms did not improve as the metabolic control improved, but insulin treatment reduced the symptoms of hyperglycaemia without increasing those of hypoglycaemia.

Neuropathy was present in 56% of the patients, compared with 15% among healthy controls (p<0.001). In most patients, neuropathy was asymptomatic. More patients had signs of carpal-tunnel syndrome. Improvement was not seen after one year of insulin treatment, nor was progression seen in the sulfonylurea-treated group of patients. Most patients (65%) had eye-ground changes, but insulin treatment did not cause more progression of retinopathy or macular oedema than oral treatment. Improved metabolic control did not affect the mean levels of insulin growth factor-I (IQF-I) or insulin growth factor binding protein-1 (IGFBP-1). High levels of IGFBP-1 indicated a need of insulin treatment, resulting in improved metabolic control and insulin sensitivity.

In conclusion, a large number of elderly diabetic patients with secondary failure of oral treatment had signs of neuropathy and retinopathy. They could effectively and at a low cost be put on insulin at a health-care centre. The resulting improvement in metabolic control did not affect blood-pressure levels and did not cause progression of retinopathy or improvement in neuropathy. The patients with high IGFBP-1 levels seem to be those who will benefit the most from insulin treatment.