Citations

Glucose homeostasis in healthy subjects is characterized by postmeal glucose increases of about 40 mg/dl, peaks at about 45 min, decreases close to antecibal levels 1 h after the peak, and no spontaneous oscillations until the next meal. Diabetes is characterized by progressive loss of glucose homeostasis from stable to unstable, which is directly proportional to loss of insulin secretory reserve. Degree of instability of diabetes in ambulatory subjects within a 24-h period can be expressed as mean amplitude of glycemic excursion of M-value and between two successive 24-h periods as mean of daily differences of blood glucose. Stable diabetic persons have lower values, which are closest to those of nondiabetic persons, and unstable diabetic persons have higher values. The mean diurnal blood glucose level is a measure of glycemic control. The failure to restore glycemic patterns of diabetic to those of nondiabetic persons is largely due to the failure of subcutaneously administered insulin to mimic the pattern of insulinemia of healthy subjects.

OBJECTIVE: Chronic hyperglycemia relates to the occurrence of diabetic polyneuropathy (DPN), but has not yet been shown to relate to its overall severity In addition, the degree and duration of hyperglycemia, which measure of chronic hyperglycemia is most predictive of defined levels of severity of DPN, and which other putative risk factors are involved remain unknown. RESEARCH DESIGN AND METHODS: In a longitudinal study of 264 diabetic individuals in Rochester, MN, risk factors and other diabetic complications assessed at regular intervals during an average of approximately 7 years were tested for their association with a composite score of severity of DPN at the last examination. RESULTS: In multivariate analysis, diabetic retinopathy severity level (at last examination), mean ln(24-h proteinuria x duration of diabetes), and mean GHb were the main covariates for severity of DPN (R2 = 0.33). Excluding markers of microvessel and macrovessel disease, the independent risk factors were mean In(GHb x duration of diabetes), GHb, and type of diabetes (R2 = 0.23). CONCLUSIONS: We found that diabetic microvessel disease, chronic hyperglycemia exposure, and type of diabetes are associated with severity of DPN, and we believe these factors are implicated in its cause. Each of the five markers of microvessel disease was a strong covariate for severity of DPN. Mean GHb predicts severity of DPN better than duration of diabetes, and the latter predicts severity of DPN better than mean fasting plasma glucose. Knowing the severity of microvessel disease, the degree of chronic hyperglycemia exposure, and the type of diabetes provides useful information to evaluate whether a coexisting polyneuropathy and its severity is probably due to diabetes.

OBJECTIVE Using a novel minimally invasive (≤ 1.4 mm) technique to sample minuscule (0.5 microliter) amounts of dermal interstitial fluid (ISF), we assessed the accuracy of its glucose concentrations in predicting concurrently measured venous plasma and capillary plasma glucose concentrations. RESEARCH DESIGN AND METHODS A total of 67 adult (37 male and 30 female) volunteers (57 with and 10 without diabetes) with venous plasma glucose levels from 1.6 to 28.4 mmol/l underwent forearm ISF, antecubetal venous, and fingertip capillary sampling. RESULTS Rank correlations were 0.974 for ISF 1 vs. 2, 0.954 for ISF vs. venous, 0.935 for ISF vs. capillary, and 0.987 for venous vs. capillary. Median absolute differences were 0.53 mmol/l for ISF 1 vs. 2, 1.33 mmol/l for ISF vs. venous, 1.06 mmol/l for ISF vs. capillary, and 0.56 mmol/l for capillary vs. venous. Equations expressing ISF glucose as a function of venous and capillary glucose and equations expressing capillary glucose as a function of venous glucose had slopes of 0.995, 0.936, and 1.021, respectively (none significantly different from unity), and intercepts of 1.03 mmol/l (P = 0.024), 0.94 mmol/l (P = 0.131), and 0.56 mmol/l (P = 0.041), respectively. Error grid analysis of ISF vs. venous glucose and of capillary vs. venous glucose showed that 97% of the measurements fell within grids A and B. CONCLUSIONS Dermal ISF sampling is a bloodless minimally invasive technique that provides a medium for glucose measurement, the concentrations of which closely reflect ambient glycemia to a degree comparable with that of capillary glucose measurements.

OBJECTIVE To evaluate both the concordance in the classification of diabetes by clinical and C-peptide criteria and, prospectively, the consistency of the classification by C-peptide. RESEARCH DESIGN AND METHODS Individuals with diabetes who were enlisted in the prospective epidemiological study of diabetic neuropathy (Rochester Diabetic Neuropathy Study [RDNS]) were classified clinically by National Diabetes Data Group (NDDG) criteria to IDDM and NIDDM at entry to the study. In addition, C-peptide response to 1 mg glucagon was measured at entry for the classification to IDDM (basal C-peptide, < 0.17 pmol/ml; increment above basal, < 0.07 pmol/ml) and NIDDM (all other responses) and for concordance with the clinical classification made. The consistency of the C-peptide response was assessed every 2 years for up to 8 years. RESULTS Among 346 individuals with diabetes, 84 were classified as IDDM and 262 as NIDDM by clinical algorithm. COncordance with the C-peptide response occurred in 89% of the patients and remained consistent during 8 years of follow-up. Among the 37 patients with discordant clinical and C-peptide classification, those considered clinically to have NIDDM had a consistent IDDM C-peptide response during follow-up, and most of those considered to have IDDM clinically eventually showed an IDDM C-peptide response during follow-up. CONCLUSIONS Clinical criteria for the classification of diabetes are highly correlated with the assessment of insulin secretory reserve. A small number of individuals considered to have NIDDM clinically or by C-peptide have or develop an IDDM peptide response.

Objective— To confirm insulinoma as the cause of hypoglycemia in a patient with NIDDM and determine the frequency of the co-occurrence of these two conditions. Research Design and Methods— The patient underwent an in-hospital prolonged fast (≤72 h), according to standard protocol, and an ultrasound examination of the pancreas. All cases of histologically confirmed insulinoma at this institution over the period of 1927–1992 were reviewed to determine the prevalence of pre-existent diabetes mellitus. Results— After 10 h of fasting, plasma glucose was low (1.89 mM); plasma insulin (258 pM) and C-peptide (1.39 nM) were elevated in the absence of sulfonylurea in the plasma. An insulinoma detected by ultrasonography was removed surgically with subsequent reoccurrence of insulin-requiring diabetes. Among 313 cases of insulinoma confirmed at this institution, this patient is the only one with pre-existent diabetes mellitus. Conclusions— Insulinoma occurs extraordinarily rarely in patients with pre-existing NIDDM.

Little information is available regarding the optimal timing of exercise in insulin-dependent diabetes mellitus (IDDM) patients. In this study, six IDDM patients receiving ultralente-based intensive insulin therapy were studied during 30 min of exercise (∼60% Vo2max), before breakfast, and at 1600. On two other occasions, they were studied at rest. Plasma glucose increased from 6.7 ± 0.4 to 9.1 ± 0.4 mM during morning exercise (P < 0.01). In contrast, mean plasma glucose did not change during afternoon exercise (≸ = 0.3 ± 0.5 mM, NS); however, there was a 0.3- to 1.0-mM decrease in three subjects. The observed difference in the glycemic response to exercise could not be explained on the basis of changes in plasma glucagon, growth hormone, norepinephrine, or epinephrine. Plasma cortisol was higher (P < 0.02) in the morning than in the afternoon, and plasma free-insulin concentrations were lower (P < 0.05). These data indicate that the risk of exerciseinduced hypoglycemia is lowest before breakfast. The reason for the divergent glycemic responses to exercise is not entirely clear but may be related to the observed differences in free-insulin concentrations. Because of the lower risk of hypoglycemia, our results suggest prebreakfast exercise may be preferable for some IDDM patients receiving intensive insulin therapy. Whether these findings are relevant to patients receiving other types of insulin therapy will require further investigation.

Increasingly more tests are being used to detect and characterize diabetic polyneuropathy, but their value in setting minimal criteria for the diagnosis of neuropathy and for staging severity remains inadequately studied. In 180 diabetics, we compared the percentage of patients with test abnormalities and associations among test results, evaluating neuropathic symptoms [neuropathy symptom score (NSS) and neuropathy scale of neuropathy symptom profile (NNSP)], deficits [neurologic disability score (NDS) and vibratory (VDT) and cooling (CDT) detection thresholds], or nerve dysfunction [nerve conduction (NC)]. The percentage of patients that were abnormal varied considerably depending on criteria for abnormality and the tests used. Abnormality (≥ 3 SD of 1 or more parameters) of NC of one or more of four nerves occurred in 80%, of two or more in 69%, of three or more in 46%, and of four in 21%. Similarly, for other tests, the rate of abnormality decreased with use of increasingly stringent criteria. Setting the criteria for abnormal NC at abnormality of two or more nerves, NSS at ≥ 1, NDS at > 6, NNSP at ≥ 97.5th percentile, and at ≥ 95th percentile for the other tests, NC was abnormal in 69%, NSS in 54%, NDS in 48%, NNSP in 47%, VDT in 44%, and CDT in 35%. Abnormality of any two or more of the six tests evaluated occurred in 64% of patients. We estimated that at least 16% of patients without abnormal NC (<2 abnormal nerves) had other findings indicative of neuropathy. By regression analysis, results of one test were in almost all cases associated with those of another test, but the association was not close enough to be predictive. Therefore, although NC provides objective and repeatable results, symptoms and deficits must be measured independently. Assuming no differences between groups of patients, the standardized and validated test (NNSP, VDT, or CDT) should provide the same results at different medical centers. By contrast, the results of NSS or NDS tests, with less standardized approaches and based on the judgment of physicians, might not provide the same results at different medical centers. Tests such as the ones described here may be used to define minimal criteria for the diagnosis of polyneuropathy and for staging its severity.

OBJECTIVE—To characterize potential differences in glycemic control, plasma lipid level, and weight in a cohort of patients previously treated with troglitazone (TROG) who were switched to either pioglitazone or rosiglitazone. RESEARCH DESIGN AND METHODS—After a 2-week washout from TROG, 186 patients were randomly assigned to receive either pioglitazone (PIO) or rosiglitazone (ROSI). Weight, HbA1c, and fasting lipid profile were documented before discontinuing TROG and at 4 months after starting either pioglitazone or rosiglitazone. Secondarily, the effect of concurrent medications on study outcomes was assessed. RESULTS—A total of 127 patients completed follow-up: 67 individuals in the PIO group (32 women, 35 men) and 60 individuals in the ROSI group (33 women, 27 men). There were no significant differences in gender mix, age, weight, fasting lipid profile, or HbA1c between the ROSI and PIO groups. After 4 months of randomized treatment, no change in HbA1c from baseline between or within groups was noted. Both groups experienced an equal and significant increase in weight from baseline of ∼2.0 kg. Thiazolidinedione and HMG-CoA reductase inhibitor therapy had significant and independent effects on lipid profile (P < 0.005). Significant improvements in lipid profile were noted in the PIO group (P < 0.01), whereas none were detected with conversion to ROSI. Specifically, the PIO group experienced an average decrease in total cholesterol of ∼20 mg/dl. CONCLUSIONS—Differing effects on lipid profile were apparent after random conversion from TROG to either PIO or ROSI, despite similar weight increase and glycemic control. The clinical significance of these differences remains to be determined, and further comparative research is warranted.

Fasting hypoglycemia, which persisted for 3 days after insulin treatment was stopped,occurred in a patient with non-insulin-dependent diabetes mellitus who had inappropriate plasma free-insulin levels (18–25 μU/ml) and extremely high antibody-bound insulin (>20,000 μU/ml) but normal counterregulatory hormone secretion and plasma C-peptide levels. The amount of antibody-bound insulin decreased in a biphasic pattern over13 mo of observation with an initial half-life of 35 days and a more gradual decrease with a half-life of 160 days. The number of high-affinity antibody binding sites was virtually identical to the amount of antibody-bound insulin in the patient's plasma. We conclude that the patient's fasting hyperinsulinemia and hypoglycemia were due to release of antibody-bound insulin.