Objectives: Insulin treatment of patients with type 2 diabetes causes hyperinsulinaemia and improves glycaemic control. We have studied how this affects risk factors for cardiovascular disease.
Design: Patients with secondary failure to oral hypoglycaemic agents were studied whilst still taking oral agents and after insulin treatment for 8 weeks in an open study.
Setting: Department of Internal Medicine, University Hospital, Linköping.
Subjects: Ten consecutive patients with type 2 diabetes and secondary failure to oral hypoglycaemic agents.
Interventions: Switching oral treatment to insulin treatment.
Main outcome measures: Effect on several cardiovascular risk factors.
Results: Fasting and postprandial plasma insulin concentrations were increased by insulin treatment whereas C-peptide concentrations were lowered. HbA1c was reduced from 8.9 +/- 0.3% (mean +/- SEM) to 6.3 +/- 0.2% after 8 weeks. There was a weight gain of 2.8 +/- 0.7 kg. Plasma concentrations of total- and very-low-density-lipoprotein (VLDL) cholesterol, VLDL-, low density lipoprotein and high-density-lipoprotein triglycerides were all reduced. The plasma concentration of apolipoprotein B was also lowered. Tissue plasminogen activator antigen measured after venous occlusion showed a significant reduction whilst plasminogen activator inhibitor 1 activity was 26.0 +/- 9.8 IU ml-1 on oral treatment and 18.2 +/- 4.7 IU ml-1 on insulin treatment (NS). Albumin excretion in the urine was reduced and the percentage reduction correlated with the percentage lowering of the tissue plasminogen activator antigen concentration after venous occlusion but not with the percentage change of basal tissue plasminogen activator antigen concentration.
Conclusions: Insulin treatment of patients with type 2 diabetes and secondary failure to oral hypoglycaemic agents causes hyperinsulinaemia and improves or has no unfavourable effect on several cardiovascular risk factors.