Comparison of fructosamine and glycated haemoglobin in children with type 1 (insulin-dependent) diabetes mellitus

Comparisons of home blood glucose testing and glycated protein measurements

We examined the relationships between 4 glycated protein assays and home blood glucose monitoring (HBGM) in 26 children with poorly-controlled insulin-dependent diabetes mellitus (IDDM) during a period of improved management. At 2 week intervals for 6 visits (12 weeks in total), HBGM records were collected and a blood sample was obtained for measurement of glycated proteins and glucose. Assays included glycated hemoglobin (GHb) and glycated serum proteins (GP) by boronate affinity chromatography, hemoglobin A1C by PolyCAT A high performance liquid chromatography (HAC) and fructosamine (FA). All 4 glycated protein levels declined significantly over the 12 week period. Significant correlations between the glycated proteins and HBGM were observed over 2 week intervals. None of the 4 assays were affected by the glucose level in the sample. Changes in mean HBGM readings over 2 week intervals were correlated with both FA and GP with wide prediction intervals. Over cumulative 2 week intervals, which may more accurately reflect longitudinal trends, all 4 glycated proteins were correlated with mean HBGM readings. At each cumulative interval, GHb and GP showed the largest variation with MBG, while FA showed the least variation with MBG. Our data indicate that of the 4 assays tested, FA has limited clinical values as compared to other glycated protein assays, whereas assays based on boronate affinity chromatography (GHb and GP) provide the most useful clinical indicators of short-term changes in glycemic control. The clinical utility of a new HPLC method for determination of glycated hemoglobins is also demonstrated.

Half-life of exogenous growth hormone following suppression of endogenous growth hormone secretion with somatostatin in type I (insulin-dependent) diabetes mellitus

OBJECTIVE

To estimate the half-life of growth hormone in young adult patients with type I (insulin-dependent) diabetes mellitus following bolus injection and prolonged exposure for the purpose of deconvolution analysis of plasma growth hormone profiles to determine growth hormone secretory rates.

DESIGN

In the bolus study, an intravenous bolus injection of 100 mU of biosynthetic human growth hormone was given while endogenous growth hormone was suppressed by a continuous infusion of somatostatin under three different glucose clamp conditions: normoglycaemia (5 mmol/l) with normoinsulinaemia (65 pmol/l); hyperglycaemia (12 mmol/l) with normoinsulinaemia; and normoglycaemia with hyperinsulinaemia (360 pmol/l). In the infusion study, the effect of prolonged and repeated growth hormone exposure upon the growth hormone half-life was estimated. Three pulses of 60 minutes growth hormone infusion (6 mU/kg/pulse) two hours apart under euglycaemic somatostatin suppression were applied.

PATIENTS

Six young adult patients with type I (insulin-dependent) diabetes mellitus were studied in both the bolus and the infusion study.

RESULTS

Mean GH half-lives by mono-exponential analysis were not significantly different remaining unaltered by the short-term metabolic changes of hyperglycaemia and hyperinsulinaemia. Data were therefore pooled yielding an overall mean GH half-life of 13.6 minutes (range 11.9-19.4). Applying a bi-exponential model mean GH half-lives were 3.1 minutes (range 2.5-5.9) for the rapid phase of distribution of the hormone and 13.8 minutes (range 9.6-16.9) for the decay of GH from the circulation. The GH half-life during the infusions studies did not vary with repeated exposure but was significantly longer (mean half-life of 25.7 minutes; range 19.4-37.1) than during the bolus studies (P less than 0.001).

CONCLUSIONS

The half-life of exogenous r-hGH is not affected by glucose or insulin concentrations but increases after prolonged GH exposure in young adults with type I (insulin-dependent) diabetes mellitus.

Randomised prospective study of short-term and long-term initial stay in hospital by children with diabetes mellitus

To assess how an isolated change in the pattern of care influences outcome of care and hospital use, a randomised prospective 2-year study was done in which 31 of 61 consecutive children with newly diagnosed insulin-dependent diabetes mellitus (IDDM) were admitted to hospital at disease onset for about a week and compared with the other 30 children who were admitted for about 4 weeks. Insulin treatment and education about diabetes were similar in the two groups. Duration of initial stay in hospital had no effect on metabolic control during the 2 years but time since diagnosis was significant with respect to effect on haemoglobin A1 (p = 0.001), haemoglobin A1c (p = 0.004), and insulin dose (p less than 0.001). At 2 years, 45% of the children in the short-term group and 29% in the long-term group were C-peptide positive (p = NS); C-peptide positivity correlated with age. A change in the pattern of care of children with IDDM, led to a pronounced decrease in hospital use by this patient group. Irrespective of the length of initial stay in hospital, equally good metabolic control was obtained in both groups for 2 years.

Longitudinal changes in serum fructosamine do not parallel those in glycated haemoglobin in young adults with insulin-dependent diabetes

In 93 adolescent and young adult patients with type 1 diabetes (163 paired comparisons) changes in fructosamine concentration correlated poorly with changes in HbA1 (r = 0.53); this correlation was no better if fructosamine values were adjusted for serum albumin by calculating a fructosamine/albumin index, F.A.I. (155 pairs, r = 0.50). These correlation coefficients were lower than those for cross-sectional comparisons (HbA1 vs. fructosamine, r = 0.74; HbA1 vs. F.A.I., r = 0.80). One-way analysis of variance showed that values of HbA1, fructosamine and F.A.I. all tended to increase as glycaemic control, judged by the clinician, worsened (P less than 0.001). HbA1 correlated better with clinical assessment than did either uncorrected fructosamine or F.A.I. We conclude that changes in fructosamine from one clinic visit to the next do not provide a basis for changing therapy. Clinical assessments tend to agree with values for HbA1, which may be more reliable than fructosamine because of its longer biological half life.

An analysis of glycosylated blood proteins and blood glucose profiles over one year in patients with type 1 diabetes

The clinical value of prospective measurement of several direct and indirect measures of blood glucose control in the management of Type 1 diabetes has been investigated. Ninety-eight Type 1 diabetic patients were followed over a period of 1 year after a 6-week period of intensification of management, with monthly measurements of blood glucose profiles and 3-monthly HbA1, glycosylated serum albumin, and fructosamine measurements. All measures improved markedly after the initial 6-week period (p less than 0.001), and all except glycosylated serum albumin and fructosamine then remained relatively stable. Of fourteen serial comparisons, glycosylated blood proteins were significantly correlated more often with levels of mean blood glucose and M value (on 4-7 occasions, rs 0.30-0.58) than with fasting blood glucose levels (on only 2-3 occasions, rs 0.34-0.44). Serum fructosamine levels correlated significantly with mean blood glucose on four occasion (rs 0.30-0.50), whilst glycosylated serum albumin and HbA1 correlated with mean blood glucose on six occasions (rs 0.36-0.54). Glycosylated serum albumin correlated with HbA1 and fructosamine levels throughout the year (rs 0.47-0.68 and 0.48-0.76, respectively), but HbA1 and fructosamine were less clearly correlated with each other (rs 0.38-0.44), with no significant association immediately after the period of intensive management or 3 months later.(ABSTRACT TRUNCATED AT 250 WORDS)