Occurrence of low blood glucose concentrations during the afternoon in Type 2 (non-insulin-dependent) diabetic patients on oral hypoglycaemic agents: importance of blood glucose monitoring

Abstract

Summary.The European NIDDM Policy Group states that the lowest target for good control of Type 2 (non-insulin-dependent) diabetic patients is a blood glucose level 4.4 mmol/1, both fasting and postprandially. The aim of this study is to evaluate the occurrence and temporal distribution of values under this target in the clinical records of 463 Type 2 diabetic patients, treated by diet or diet and oral hypoglycaemic agents, monitored for at least 2 years. The protocol includes blood glucose measurements after overnight fasting (08.00 hours), 120-150 rain after breakfast (11.00 hours) and 120 and 240 min after lunch (14.00 and 16.00 hours). At least one blood glucose concentration of less than 4.4 mmol/1 was presented by 42% of the patients. The only difference between patients showing and not showing glycaemic levels under this target was the higher percentage on oral hypoglycaemic agents in the first group (68.4% vs 56.9% ,p = 0.016). We considered 299 blood glucose profiles containing at least one value of less than 4.4 retool/l, observing that a) 46.9% of profiles from patients treated by diet alone and 68.7% of profiles from patients treated both by diet and oral hypoglycaemic agents presented the lowest blood glucose concentration at 16.00 hours (p = 0.002). b) No correlation existed between fasting blood glucose and values at 16.00 hours in profiles from diet-treated patients, whereas a negative correlation was present in patients on diet and oral hypoglycaemic agents, indicating that an excess of oral agents, administered to correct fasting hyperglycaemia, was the cause of the low glycaemic values in the afternoon, c) 37.9% of profiles on a diet and 83.3% of profiles on diet and oral agents showed fasting glucose concentrations > 6.7 mmol/1, the upper limit of good control according to the European NIDDM Policy Group. This indicates that fasting hyperglycaemia does not exclude the occurrence of low glucose values throughout the day and that it is necessary to monitor blood glucose profiles.

Activation of Oxidative Stress by Acute Glucose Fluctuations Compared With Sustained Chronic Hyperglycemia in Patients With Type 2 Diabetes

“…We therefore suggest that the triggering effect of acute glycemic excursions on oxidative stress should be integrated into glycemic disorders that are larger than acute postmeal spikes, 39,51,53 ie, into rapid glucose swings including the declines from relatively high glucose levels during postprandial periods 53 to low values or even to asymptomatic hypoglycemia, as observed over interprandial periods. 54,55 As a consequence, low glycemic levels in type 2 diabetes might stimulate oxidative stress; this observation is consistent with the fact that platelet aggregation can be activated during moderate insulin-induced hypoglycemia in type 1 diabetes. 56 In conclusion, the present study demonstrates a significant relationship between acute glucose swings and activation of oxidative stress.…”

Postprandial Blood Glucose Predicts Cardiovascular Events and All-Cause Mortality in Type 2 Diabetes in a 14-Year Follow-Up

“…Note also that all patients considered in that study were on hypoglycemic treatment (24): either combination oral regimen with a sulphonylurea plus metformin or insulin, with or without concomitant oral agents; thus, they were at hypoglycemic risk. The absence of a U-shaped association in our cohort could be explained by the great attention we always paid to avoid hypoglycemia and also by considering the results of blood glucose profiles (13,14); in particular, because 92.2% of patients in the first A1C decile were on diet alone and therefore not at hypoglycemic risk, we can exclude that low A1C values were due to hypoglycemic episodes.…”

“…This phenomenon is attributable to the fact that in type 2 diabetes the glycemic baseline on which postmeal peaks are superimposed (the so-called “pre-prandial baseline”) is not stable but declines from morning to evening even in patients on diet alone, likely because of waning of the early-morning increase in counterregulatory hormones (12). Not surprisingly, in patients on oral agents hypoglycemia is frequent in the late afternoon (14). …”

Glycemic Variability: Assessing Glycemia Differently and the Implications for Dietary Management of Diabetes

“…The deleterious effects of vacillating glucose levels may not be limited to postmeal spikes but may also include hypoglycemic variability, characterized by rapid declines in blood glucose following meals, or asymptomatic hypoglycemia during interprandial periods that may increase risk (155,225). Furthermore, severe hypoglycemia can be preceded by blood glucose disruptions (127), and GV has been proposed as a possible predictor of hypoglycemia, with studies showing that a lower GV is associated with fewer hypoglycemic episodes (131).…”

“…However, single, isolated blood glucose measurements inadequately describe a diurnal glucose profile and do not accurately reflect longterm glucose concentrations (21,24,188). For example, fasting hyperglycemia does not preclude the occurrence of hypoglycemia later in the day (225).…”