Upsala J Med Sci 96: 47-61, 1991 Metabolic Control, Residual Insulin Secretion and Self-care Behaviours in a Defined Group of Patients with Type 1 Diabetes Karin Wikblad, Kent Montin and Lars Wibell Department of Internal Medicine, Centre for Caring Sciences, Uniuersity Hospital, Uppsala and Department of Education, Uppsala University ABSTRACT A population of 185 type 1 diabetes patients (insulin-dependent, IDDM), 25-45 years old, was studied retro- and prospectively over a 9-year period with the aim of analysing background factors of importance for the ability to perform adequate self-care. Expressed as mean HbAlc, the metabolic control was slightly improved at the end of the study, when the insulin schedule had been changed in 60 % of the patients to multidose treatment. The degree of metabolic control remained constant over the years. The impact of residual insulin secretion, measured as 24-hour urinary C peptide, was low. Patients with less good metabolic control often had a poor educational background and made less use of self-monitoring of blood glucose (SMBG); they also experienced difficulties with SMBG. The applied knowledge of diabetes also differed between groups with good and poor control. Subjectively, most patients considered their metabolic control to be good, irrespective of the HbAlc values. When asked about their own diabetes complications, their answers were often discrepant from the medical records. Patients with particularly "good" or "poor" metabolic control were on the whole less satisfied with the education and information received than those with intermediate blood glucose regulation. Development of strategies for individually adjusted education seems important. INTRODUCTION During the last decade patients with type 1 diabetes have increasingly been expected to be active participants in their own treatment, and to perform adequate self-care. Factors influencing the patient's ability to do this and to achieve satisfactory metabolic control have been subject to vast investigations but are still not clear. Studies on self-care performance often deal mainly with psychological influences on the performance (3,5). Other studies have medical and metabolic factors in focus, such as the residual insulin secretion, modes of insulin administration, technology for self-determinations of blood glucose, and so on ( 2 , 14-18). Sjoberg et a1 (15) suggested that patients without any residual insulin secretion might experience more restrictions of their life-style compared with patients with a measurable amount of C peptide. It has been proposed that changes in the management of type 1 diabetes, with the introduction of flexible multidose insulin regimes (2, 14, 16) and self-monitoring 47 of blood glucose (14, 17-18), may have a positive influence on the patient's daily self-care and on the metabolic control of the diabetes. Education of the patients has long been viewed as an important component of the treatment of diabetes (1, 4, 1 l), although the knowledge per se sometimes has only a limited effect on the performance. A number of studies have been focused on the influence of social factors on self-care and metabolic control ( 6 , 8-9, 12-13, 19). Some of them have dealt with factors influencing compliance with treatment (8, 12,24), and others have pointed to the importance of social support (9, 12). The selection of patients has varied between different studies reported in the literature, and the degree to which patient materials are described is also highly variable. In the present study an analysis was made of diabetes-related variables in a well-defined group of patients with type 1 diabetes with the aim of identifying factors affecting the patient's ability to achieve adequate self-care. SUBJECTS AND METHODS Investigated ~ O U D To obtain a defined and representative sample of type 1 diabetic patients with experience of living with diabetes, the following criteria were established: 1. born between 1939 and 1959, 2. duration of diabetes of at least 5 years (onset of diabetes in 1975 or earlier), 3. currently treated with 2 20 U insulin daily. Of the 1025 patients with type 1 or type 2 diabetes who in 1984/85 were regularly visiting the out- patient clinic at the University Hospital in Uppsala, 193 patients fulfilled these three criteria. At the first screening it was discovered that five of the patients had to be excluded because of brain lesions or mental retardation. Three other patients declined to participate. Thus the final number of patients in this survey was 185. General Drocedure For the period 1980-84 a retrospective evaluation was performed. It was possible here to include an assessment of "long-term metabolic control". Glycosylated haemoglobin (HbA lc) had been measured routinely at all out-patient visits since 1980. The patient files also contained reliable information about the duration of diabetes, the treatment schedule and the size of the total insulin dose, height and body weight, serum creatinine and the presence of albuminuria. Most patients also underwent regular screening for retinopathy. In 1985 a cross-sectional study was performed. A questionnaire was mailed to 170 of the 185 patients (12 were excluded because of advanced visual impairment, 2 patients had moved abroad and 1 patient had died). After two reminders it was completed by 139 patients (77 males and 62 females). The 31 "drop-outs" from this inquiry showed a higher percentage of male subjects and a higher mean HbAlc than the total material. The cross-sectional study included measurement of C peptide in the urine in those 166 of the 185 patients from whom an apparently reliable 24-h urine specimen could be obtained. In 1985-1988 a prospective evaEuation of the further treatment and metabolic control of the 48 patients was undertaken. DroD-outs: During the 5 years of the prospective study three patients died and 11 moved from the area. Methods GZycosyZated haemoglobin (here called HbAlc) was initially assayed by means of total HbAl microcolumns (Bio-Rad, Richmond) and later by HbAlc methods (Bio-Rad, Pharmacia HPLC System). The methods correlate well in linear regression, with correlation coefficients of 0.96-0.98 during periods of double determinations at the laboratory. Thus all HbAlc values were converted to HbAlc %. The upper normal limit (mean f 2SD) was 6.1 % in subjects with a normal oral glucose tolerance test. HbAlc was usually measured 3-5 times yearly. The classification of retinopathic changes (mainly based on photometric examinations performed by the same ophthalmologist) comprised three categories: no important retinopathic changes, simplex retinopathy (background retinopathy) and preproliferative-proliferative retinopathy. Renalfirnction was evaluated by means of AlbustixB strips at alI visits. For the serum creatinine method of the hospital laboratory, the reference limits were 64-106 pnoM . The relative body mass index ( BMI) was used to describe the body weight. Relative BMI was calculated from an ideal BMI of 20.9 kg/m2 in females and 22.4 kg/rn2 in males, as proposed by West (21). For screening of Cpeptide in the urine, a commercial kit (Behringwerke) was used.The method was applied semiquantitatively (C peptide below the detection level of ~ 0 . 4 nmoV24 h, above the detection level but low, 0.4-3.9 nmoV24 h, or within the reference limits of 4.0-50 nmoV24 h). The self-care questionnaire was constructed to obtain demographic data, social data and information concerning subjective health perception, self-care ability, the educational level and applied knowledge about diabetes. The questionnaire consisted of 29 multiple-choice questions, 17 open-ended questions and 5 Likert scales for self-estimation of physical health. The social data were classified according to the socio-economic classification system (SEI) deveIoped by Statistics, Sweden ( a copy of the questionnaire is supplied by the authors on request). Statistical methoak: Some results are simply presented as group mean values fSD. According to the data level, median values have also been used. For comparison of mean values, the t test was used and proportions were compared with the use of chi-square tests. Correlations were calculated by Pearson's product-moment correlation coefficient and the Spearman-Rank correlation. One factor Anova (two-tailed) was used for group comparison. RESULTS CLINICAL CHARACTERISTICS Age and duration In 1985, as implied by the inclusion criteria, all patients were between 26 and 46 years old, with the same mean age of 36 for males (n= 104) and females (n= 81). The mean age at onset of diabetes (total range 1-33 years) was 15.5 k7.7 years in male and 12.3 f 7.9 years in female subjects. The total mean duration of diabetes was 22.1 years k 8.5 (range 10-41 years). 4-91 8571 49 HbA 1 c values During the five-year baseline period 1980-1984 the mean HbAlc value in the whole material was 8.7 f1.2 %. In 1986 the mean HbAlc was unchanged, 8.7 f1.5 %, and in 1988 it was significantly lower, 8.3 f1.2 % (p 8.5% (p < 0.01). Ninety-seven per cent of the patients with good metabolic control and 90 % of those with unacceptable control had serum creatinine values within the reference limits. 5 1 Table 3 B. Percentage number of type 1 diabetic patients "without proteinuria" as related to the mean HbAlc level during the five-year period 1980-1984. HbA l c n diabetes duration % with negative proteinuria test 1980-84 (me&SD) 1980 1984 1986 1988 17.5 (I) 34 22.0+_7.7 97 91 88 88 7.6-8.4 (II) 47 24.0f8.1 91 77 77 77 8.5-9.4 (III) 53 24.9k9.9 75 64 66 58 1 9 . 5 (IV) 51 2 1.1k7.7 67 49 55 47 Stability of metabolic control (Fig.1) In the analysis of the possible effect of metabolic control on the rate of occurrence of late complications of diabetes (Tables 3 A and 3 B), and in the study of self-monitoring of blood glucose and other aspects of self-care, it was of interest to assess the degree of fluctuation between good and poor metabolic control. In this respect considerable stability was found. In each of the four metabolic control groups (Table l), the mean HbAlc value was calculated for each of the years 1980, 1984, 1986 and 1988, and no change was found in any of the groups over this 9-year period (Fig 1). If the mean HbAlc for 1988 instead of the mean for the period 1980-1984 had been used as a basis of the grouping, some patients would of course have been allocated to a group above or below the previous rating (borderline cases), but only 18 of the 185 patients would have had to be moved two steps or more upwards or downwards on the 4-grade scale. 1 E 9 n 4 __cpz_ GroupIII U 3 $ 8 4 GroupII 6 1 1980-84 1980 1984 1986 1988 Year Figure 1: The mean values of HbAlc in the four groups of patients with type 1 diabetes (n=34-53) with different degrees of metabolic control, as defined in Table 1, in 1980-1984, are shown to the left. The mean HbAlc for each of these groups in four different years betwcen 1980 and 1988 is then shown, to illustrate the degree of stability over this 9-year period. Residual insulin secretion The %hour excretion of urine C peptide was determined in 90 % of the 185 patients. As expected, with a mean duration of 22 years and a shortest duration of 10 years, the majority of the patients had no or very little urinary C peptide. No or only a small amount (< 0.4 nmoV24 h) 5 2 was found in 133 patients. Twenty-two patients had a definitr, excretion but so low that it was clearly in accordance with type 1 diabetes. Eleven patients had C-peptide excretion of such a magnitude that it was likely to be of clinical importance (2 4.0 nmo1/24 h). The 33 patients with a detectable amount of C peptide in the urine were matched according to sex, age and duration of diabetes with 33 patients with non-detectable levels of C peptide. The two groups each consisted of 18 males and 15 females. The mean age of the two groups of patients was 38 f 5 years and the mean duration of their diabetes was 22 years (22k9 in the C-peptide group and 22k10 in the matched group). The mean HbAlc values were only slightly lower in the patients with urinary C-peptide excretion (excretors) than in those without detectable C peptide in the urine (non-excretors) (excretors: 8.7f1.30%; non-excretors: 9.3+1.65%) and there was no correlation between HbAlc values and urinary C-yeptide values (r=-0.07). There was no difference between the two groups in the daily amount of insulin administered (0.65 M.18 Uikg/day in C-peptide excretors and 0.68f0.17 in non-excretors). Neither was there any difference in relative BMI. The urinary C-peptide excretion showed no correlation with the daily amount of insulin (r=0.20), but was weakly correlated with relative BMI (-0.31). There was a tendency (n.s) towards a lower frequency of late complications among excretors than among non-excretors: 15 excretors had retinopathic changes, against 20 non-excretors, and three had proliferative retinopathy, against six non-excretors; for albuminuria the figures were five and ten (p<0.02). The two groups gave similar answers to the self-care questionnaire. SOCIAL CHARACTERISTICS Seventy-four per cent of the patients were married or living with a partner, without any differences between the four HbAlc groups. The type of occupation of the partners differed, however, between group IV and the other three groups. Fifty-six per cent of the group IV partners were manual workers, compared with 9% of those of group I, 22% of those of group I1 and 21 % of those of group III (p