Marco Ciofetta

Meticulous Prevention of Hypoglycemia Normalizes the Glycemic Thresholds and Magnitude of Most of Neuroendocrine Responses to, Symptoms of, and Cognitive Function During Hypoglycemia in Intensively Treated Patients With Short-Term IDDM

To test the hypothesis that hypoglycemia unawareness is largely secondary to recurrent therapeutic hypoglycemia in IDDM, we assessed neuroendocrine and symptom responses and cognitive function in 8 patients with short-term IDDM (7 yr) and hypoglycemia unawareness. Patients were assessed during a stepped hypoglycemic clamp, before and after 2 wk and 3 mo of meticulous prevention of hypoglycemia, which resulted in a decreased frequency of hypoglycemia (0.49 ± 0.05 to 0.045 ± 0.03 episodes/patient-day) and an increase in HbA1c (5.8 ± 0.3 to 6.9 ± 0.2%) (P < 0.05). We also studied 12 nondiabetic volunteer subjects. At baseline, lower than normal symptom and neuroendocrine responses occurred at lower than normal plasma glucose, and cognitive function deteriorated only marginally during hypoglycemia. After 2 wk of hypoglycemia prevention, the magnitude of symptom and neuroendocrine responses (with the exception of glucagon and norepinephrine) nearly normalized, and cognitive function deteriorated at the same glycemic threshold and to the same extent as in nondiabetic volunteer subjects. At 3 mo, the glycemic thresholds of symptom and neuroendocrine responses normalized, and surprisingly, some of the responses of glucagon recovered. We concluded that hypoglycemia unawareness in IDDM is largely reversible and that intensive insulin therapy and a program of intensive education may substantially prevent hypoglycemia and at the same time maintain the glycemic targets of intensive insulin therapy, at least in patients with IDDM of short duration.

Acute, short-term hyperglycemia enhances shear stress-induced platelet activation in patients with type II diabetes mellitus

OBJECTIVES The aim of our study was to assess whether acute, short-term hyperglycemia affects platelet reactivity in patients with Type II diabetes mellitus (T2DM). BACKGROUND Hyperglycemic spikes are thought to precipitate ischemic events in T2DM. Previous studies have shown in vivo platelet activation in diabetes; however, no studies have assessed whether acute in vivo hyperglycemia induces further activation of platelets. METHODS In a cross-over, randomized, double-blind study, 12 patients with T2DM underwent 4 h of either acute hyperglycemia (13.9 mmol/l, 250 mg/dl) or euglycemia (5.5 mmol/l, 100 mg/dl). Shear stress-induced platelet activation, P-selectin and lysosomal integral membrane protein (LIMP) expression on platelets in the bleeding-time blood, urinary 11-dehydro-thromboxane B(2) (TxB(2)) excretion, von Willebrand factor:antigen (vWF:Ag), and von Willebrand factor:activity (vWF:activity) were measured before and after hyperglycemia or euglycemia. RESULTS Shear stress-induced platelet activation, P-selectin and LIMP expression on platelets in the bleeding-time blood, and urinary 11-dehydro-TxB(2) excretion increased significantly after hyperglycemic clamping, whereas no changes were observed after euglycemic clamping. Plasma vWF:Ag and vWF:activity increased strikingly in parallel fashion after hyperglycemic clamping, whereas no changes were observed after euglycemic clamping. CONCLUSIONS Our data demonstrate that acute, short-term hyperglycemia induces an increased activation of platelets exposed to high shear stress conditions in vitro (filtration method) or in vivo (bleeding time). In vivo platelet activation is reflected by an increased urinary excretion of 11-dehydro-TxB(2). The increased levels of vWF in the circulation correlate with the increase in platelet activation markers and may indicate some degree of causation. Acute, short-term hyperglycemia in T2DM may precipitate vascular occlusions by facilitating platelet activation.

Long-term recovery from unawareness, deficient counterregulation and lack of cognitive dysfunction during hypoglycaemia, following institution of rational, intensive insulin therapy in IDDM.

SummaryHypoglycaemia unawareness, is a major risk factor for severe hypoglycaemia and a contraindication to the therapeutic goal of near-normoglycaemia in IDDM. We tested two hypotheses, first, that hypoglycaemia unawareness is reversible as long as hypoglycaemia is meticulously prevented by careful intensive insulin therapy in patients with short and long IDDM duration, and that such a result can be maintained long-term. Second, that intensive insulin therapy which strictly prevents hypoglycaemia, can maintain long-term near-normoglycaemia. We studied 21 IDDM patients with hypoglycaemia unawareness and frequent mild/severe hypoglycaemia episodes while on “conventional” insulin therapy, and 20 nondiabetic control subjects. Neuroendocrine and symptom responses, and deterioration in cognitive function were assessed in a stepped hypoglycaemia clamp before, and again after 2 weeks, 3 months and 1 year of either intensive insulin therapy which meticulously prevented hypoglycaemia (based on physiologic insulin replacement and continuous education, experimental group, EXP, n=16), or maintenance of the original “conventional” therapy (control group, CON, n=5). At entry to the study, all 21 IDDM-patients had subnormal neuroendocrine and symptom responses, and less deterioration of cognitive function during hypoglycaemia. After intensive insulin therapy in EXP, the frequency of hypoglycaemia decreased from 0.5±0.05 to 0.045±0.02 episodes/patient-day; HbA1C increased from 5.83±0.18 to 6.94±0.13% (range in non-diabetic subjects 3.8–5.5%) over a 1-year period; all counterregulatory hormone and symptom responses to hypoglycaemia improved between 2 weeks and 3 months, with the exception of glucagon which improved at 1 year; and cognitive function deteriorated further as early as 2 weeks (p<0.05). The improvement in responses was maintained at 1 year. The improvement in plasma adrenaline and symptom responses inversely correlated with IDDM duration. In contrast, in CON, neither frequency of hypoglycaemia, nor neuroendocrine responses to hypoglycaemia improved. Thus, meticulous prevention of hypoglycaemia by intensive insulin therapy reverses hypoglycaemia unawareness even in patients with long-term IDDM, and is compatible with long-term near-normoglycaemia. Because carefully conducted intensive insulin therapy reduces, not increases the frequency of moderate/severe hypoglycaemia, intensive insulin therapy should be extended to the majority of IDDM patients in whom it is desirable to prevent/delay the onset/progression of microvascular complications.

Relative roles of insulin and hypoglycaemia on induction of neuroendocrine responses to, symptoms of, and deterioration of cognitive function in hypoglycaemia in male and female humans.

SummaryTo assess the relative roles of insulin and hypoglycaemia on induction of neuroendocrine responses, symptoms and deterioration of cognitive function (12 cognitive tests) during progressive decreases in plasma glucose, and to quantitate glycaemic thresholds, 22 normal, non-diabetic subjects (11 males, 11 females) were studied on four occasions: prolonged fast (n=8, saline euglycaemia study, SA-EU), stepped hypoglycaemia (plasma glucose plateaus of 4.3, 3.7, 3 and 2.3 mmol/l) or euglycaemia during insulin infusion at 1 and 2 mU·kg−1·min−1 (n=22, high-insulin hypoglycaemia and euglycaemia studies, HI-INS-HYPO and HI-INS-EU, respectively), and stepped hypoglycaemia during infusion of insulin at 0.35 mU· kg−1·min−1 (n=9, low-insulin hypoglycaemia study, LO-INS-HYPO). Insulin per se (SA-EU vs HI-INS-EU), suppressed plasma glucagon (∼20%) and pancreatic polypeptide (∼30%), whereas it increased plasma noradrenaline (∼R10%, p<0.05). Hypoglycaemia per se (HI-INS-HYPO vs HI-INS-EU) induced responses of counterregulatory hormones (CR-HORM), symptoms and deteriorated cognitive function. With the exception of suppression of endogenous insulin secretion, which had the lowest glycaemic threshold of 4.44±0.06 mmol/l, pancreatic polypeptide, glucagon, growth hormone, adrenaline and cortisol had similar glycaemic thresholds (∼3.8-3.6 mmol/l); noradrenaline (3.1±0.0 mmol/l), autonomic (3.05±0.06 mmol/l) and neuroglycopenic (3.05±0.05 mmol/l) symptoms had higher thresholds. All 12 tests of cognitive function deteriorated at a glycaemic threshold of 2.45±0.06 mmol/l, but 7 out of 12 tests were already abnormal at a glycaemic threshold of 2.89±0.06 mmol/l. Although all CR-HORM had a similar glycaemic threshold, the lag time of response (the time required for a given parameter to increase) of glucagon (15±1 min) and growth hormone (14±3 min) was shorter than adrenaline (19±3 min) and cortisol (39±4 min) (p<0.05). With the exception of glucagon (which was suppressed) and noradrenaline (which was stimulated), insulin per se (HI-INS-HYPO vs LO-INS-HYPO) did not affect the responses of CR-HORM, and did not influence the symptoms or the cognitve function during hypoglycaemia. Despite lower responses of glucagon, adrenaline and growth hormone (but not thresholds) in females than males, females were less insulin sensitive than males during stepped hypoglycaemia.

Pharmacokinetics, pharmacodynamics and glucose counterregulation following subcutaneous injection of the monomeric insulin analogue [Lys(B28),Pro(B29)] in IDDM

SummaryThe aim of these studies was to compare the pharmacokinetics, pharmacodynamics, counterregulatory hormone and symptom responses, as well as cognitive function during hypoglycaemia induced by s. c. injection of 0.15 IU/kg of regular human insulin (HI) and the monomeric insulin analogue [Lys(B28),Pro (B29)] (MI) in insulin-dependent-diabetic (IDDM) subjects. In these studies glucose was infused whenever needed to prevent decreases in plasma glucose below 3 mmol/l. After MI, plasma insulin increased earlier to a peak (60 vs 90 min) which was greater than after HI (294±24 vs 255±24 pmol/l), and plasma glucose decreased earlier to a 3 mmol/l plateau (60 vs 120 min) (p<0.05). The amount of glucose infused to prevent plasma glucose falling below 3 mmol/l was ∼three times greater after MI than HI (293±26 vs 90±25 μmol · kg−1 · 60–375 min−1, p<0.05). After MI, hepatic glucose production was more suppressed (0.7±1 vs 5.9±0.54 μmol · kg−1 · min−1) and glucose utilization was less suppressed than after HI (11.6±0.65 vs 9.1±0.11μmol · kg−1 · min−1) (p<0.05). Similarly, plasma NEFA, glycerol, and β-OH-butyrate were more suppressed after MI than HI (p<0.05), whereas plasma lactate increased only after MI, but not after HI. Responses of counterregulatory hormones, symptoms and deterioration in cognitive function during plasma glucose plateau of 3 mmol/l were superimposable after MI and HI (p=NS). Post-hypoglycaemia hyperglycaemia was greater after MI than HI (at 480 min 12.1±1 vs 11±1 mmol/l) because of greater hepatic glucose production during insulin waning which occurred at least 135 min earlier with MI as compared to HI (p<0.05). It is concluded that counterregulatory hormones, symptoms and deterioration in cognitive function during hypoglycaemia respond similarly after MI and HI. The biological effect of MI appears greater than that of HI for at least 4 h after the s.c. injection and appears as a good candidate for achieving optimal post-prandial glucose control in IDDM.

Use of the short-acting insulin analogue lispro in intensive treatment of type 1 diabetes mellitus : Importance of appropriate replacement of basal insulin and time-interval injection-meal

To establish whether lispro may be a suitable short‐acting insulin preparation for meals in intensive treatment of Type 1 diabetes mellitus (DM) in patients already in chronic good glycaemic control with conventional insulins, 69 patients on intensive therapy (4 daily s.c. insulin injections, soluble at each meal, NPH at bedtime, HbA1c <7.5 %) were studied with an open, cross‐over design for two periods of 3 months each (lispro or soluble). The % HbA1c and frequency of hypoglycaemia were assessed under four different conditions (Groups I–IV). Lispro was always injected at mealtime, soluble 10–40 min prior to meals (with the exception of Group IV). Bedtime NPH was continued with both treatments. When lispro replaced soluble with no increase in number of daily NPH injections (Group I, n = 15), HbA1c was no different (p = NS), but frequency of hypoglycaemia was greater (p < 0.05). When NPH was given 3–4 times daily, lispro (Group II, n = 18), but not soluble (Group III, n = 12) decreased HbA1c by 0.35 ± 0.25 % with no increase in hypoglycaemia. When soluble was injected at mealtimes, HbA1c increased by 0.18 ± 0.15% and hypoglycaemia was more frequent than when soluble was injected 10–40 min prior to meals (Group IV, n = 24) (p < 0.05). It is concluded that in intensive management of Type 1 DM, lispro is superior to soluble in terms of reduction of % HbA1c and frequency of hypoglycaemia, especially for those patients who do not use a time interval between insulin injection and meal. However, these goals cannot be achieved without optimization of basal insulin.

Contribution of Autonomic Neuropathy to Reduced Plasma Adrenaline Responses to Hypoglycemia in IDDM: Evidence for a Nonselective Defect

To determine the contribution of clinically overt diabetic autonomic neuropathy (DAN) to reduced plasma adrenaline responses to hypoglycemia in IDDM and to establish its selectivity for hypoglycemia, we studied 17 IDDM patients (7 without DAN [DAN−] and 10 with DAN [DAN+]), of whom 5 had and 5 did not have postural hypotension (DAN+PH+ and DAN+PH−, respectively), and 8 nondiabetic subjects on 2 different occasions, i.e., clamped hypoglycemia (steps from 5.0 to 2.2 mmol/l plasma glucose) and 30-min steady-state exercise at 55% VO2max. Recent antecedent hypoglycemia was meticulously prevented before the studies to exclude hypoglycemia as a cause of reduced responses of adrenaline to hypoglycemia. In DAN− patients, maximal responses of adrenaline to hypoglycemia were reduced (2.44 ± 0.58 nmol/l vs. 4.9 ± 0.54 nmol/l in nondiabetic patients) (P < 0.05). In DAN+, adrenaline responses initiated at a lower plasma glucose and were lower than in DAN− (DAN+PH−, 1.06 ± 0.38 nmol/l; DAN+PH+, 0.84 ± 0.27 nmol/l; P < 0.001, but NS between PH− and PH+). In response to exercise, adrenaline increased less in DAN− (0.89 ±0.11 nmol/l) patients than in nondiabetic subjects (1.19 ± 0.14 nmol/l; NS) and only to 0.36 ± 0.07 nmol/l in DAN+PH− and 0.23 ± 0.09 nmol/l in DAN+PH+ (P < 0.001 vs. DAN− and nondiabetic subjects). These results were confirmed when nondiabetic and DAN− subjects repeated the exercise at 60 watts (35 and 41% of Vo2max, respectively), i.e., at the same absolute workload of DAN+ patients. Thus, DAN (both PH+ and PH−) contributes to reduced responses of adrenaline to hypoglycemia independently of recent antecedent hypoglycemia. The adrenaline defect in DAN is not selective for hypoglycemia.

Evidence of Increased Systemic Glucose Production and Gluconeogenesis in an Early Stage of NIDDM

To assess the mechanisms of fasting hyperglycemia in NIDDM patients with mild elevation of fasting plasma glucose (FPG) compared with NIDDM patients with overt hyperglycemia, we studied 29 patients with NIDDM, who were divided in two groups according to their fasting plasma glucose (<7.8 and ≥7.8 mmol/l for groups A and B, respectively), and 16 control subjects who were matched with NIDDM patients for age, sex, and body mass index. All subjects were infused with ]3-3H]glucose between 10:00 P.M. and 10:00 A.M. during overnight fasting to determine glucose fluxes. In 27 subjects (17 diabetic and 10 control), ]U-14C]alanine was simultaneously infused between 4:00 A.M. and 10:00 A.M. to measure gluconeogenesis (GNG) from alanine. Arterialized- venous plasma samples were collected every 30 min for measurement of glucose fluxes, GNG, and glucoregulatory hormones. In group A, plasma glucose, rate of systemic glucose production (SGP), and GNG were greater than in control subjects (7.2 ± 0.2 vs. 4.9 ± 0.1 mmol/l, 10.9 ± 0.2 vs. 9.5 ± 0.3 μmol · kg−1 · min−1, and 0.58 ± 0.04 vs. 0.37 ± 0.02 μmol · kg−1 · min−1, respectively, for group A and control subjects; mean value 8:00 A.M.-10:00 A.M., all P < 0.05). Both increased SGP and GNG correlated with plasma glucose in all subjects (r = 0.77 and r = 0.75, respectively, P < 0.005). Plasma counterregulatory hormones did not differ in NIDDM patients compared to control subjects. The present studies demonstrate that SGP and GNG are increased in NIDDM patients without overt fasting hyperglycemia.Thus these metabolic abnormalities primarily contribute to early development of overnight and fasting hyperglycemia in NIDDM.

Improved Postprandial Metabolic Control After Subcutaneous Injection of a Short-Acting Insulin Analog in IDDM of Short Duration With Residual Pancreatic β-Cell Function

OBJECTIVE To compare postprandial metabolic control after subcutaneous injection of a short-acting insulin analog [Lys(B289),Pro(B29)] (Lispro) or human regular insulin (Humulin R U-100 [Hum-R]) in insulin-dependent diabetes mellitus (IDDM) of short duration with residual β-cell function. RESEARCH DESIGN AND METHODS Six IDDM patients (age 25 ± 2 years, diabetes duration 14 ± 2 months, HbA1c 6.4 ± 0.5%) with residual pancreatic β-cell function (fasting plasma C-peptide 0.19 ± 0.02 nmol/l) were studied on three different occasions. Postbreakfast plasma glucose was maintained at ∼ 7.1 mmol/l by means of intravenous insulin until either 1200 when 0.1 U/kg Hum-R was injected or until 1225 when 0.1 U/kg of either Hum-R or Lispro was injected subcutaneously. Lunch (mixed meal, 692 Kcal) was served at 1230 (0 min). Six nondiabetic control subjects were also studied. RESULTS After Lispro administration, the 120-min plasma glucose decreased more (6.1 ± 0.3 mmol/l) than after injection of Hum-R at −30 min (7.7 ± 0.3 mmol/l) or −5 min (9.9 ± 0.2 mmol/l). By the end of the study, plasma glucose was still lower after Lispro was injected (6.7 ± 0.3 mmol/l) than after Hum-R was injected at −30 min (7.6 ± 0.3 mmol/l) or −5 min (7.3 ± 0.2 mmol/l) (P < 0.05). Two IDDM patients required glucose to prevent hypoglycemia after being injected with Lispro, but four required glucose after being injected with Hum-R at −5 min (Lispro ∼ 27 mmol glucose infused between 90 and 240 min; Hum-R ∼ 80 mmol between 240 and 390 min). After Lispro, plasma insulin peaked earlier (at 30 min, 342 ± 29 pmol/l) than after Hum-R injection at −30 min (at 90 min, 198 ± 28 pmol/l) and was superimposable on that of nondiabetic subjects. In Hum-R injected at −5 min, plasma insulin peaked later (at 120 min) and subsequently remained > in the two other studies. CONCLUSIONS Despite the lack of a time interval between injection and meal, Lispro controls postprandial plasma glucose concentration better than Hum-R given 30 min before meals and, to an even greater extent, better than Hum-R given 5 min before meals. In addition, Lispro minimizes the risk of postprandial hypoglycemia, thus closely mimicking the postprandial glucose homeostasis of nondiabetic subjects. IDDM patients with residual pancreatic β-cell function are the ideal candidates for prandial use of Lispro because they can maintain near-normoglycemia longer after subcutaneous analog injection because of residual endogenous insulin secretion.

Long-term intensive insulin therapy in IDDM: effects on HbA1c, risk for severe and mild hypoglycaemia, status of counterregulation and awareness of hypoglycaemia

SummaryThe present studies were designed to assess the percentage of HbA1c, frequency, and awareness of hypoglycaemia (H) during long-term intensive therapy (IT) of insulin-dependent diabetes mellitus (IDDM). From 1981 to 1994, 112 IDDM patients were on IT. HbA1c was 7.17±0.16% (non-diabetic subjects 3.8–5.5%), the frequency of severe H 0.01±0.009 episodes/patient-year, frequency of mild symptomatic H 35.6±2.9 episodes/patient-year. IDDM patients with HbA1c ≤ 5.5% (Group I, n=10), between 6.1–7.0% (Group II, n=12), and ≥ 7.6% (Group III, n=11) were studied to assess responses of counterregulatory hormones, symptoms and cognitive function during experimental, stepped H. Compared to 18 non-diabetic subjects, Group I exhibited high thresholds (plasma glucose had to decrease more than normal to evoke responses), and impaired responses of adrenaline, unawareness of H and delayed onset of cognitive dysfunction at the lowest glycaemic plateau (2.3 mmol/l). Group II had normal thresholds and responses, whereas Group III had low thresholds. Frequency of mild H was higher in Group I (54.5±1.9 episodes/patient-year) than in Group II and III (33.7±3.5 and 20.4±2.5 episodes/ patient-year, respectively, p<0.001) and correlated with percentage of HbA1c (r=−0.82). In conclusion: IT can maintain near-normal HbA1c and is compatible with low frequency of severe H. However, if HbA1c is less than 6.0%, mild, symptomatic H is excessively frequent and causes impaired counterregulation and H unawareness. Efforts should be made not only to maintain HbA1c ≤ 7.0%, but also to prevent, recognize and reverse iatrogenic H unawarenes during long-term IT of IDDM by maintaining HbA1c>6.0%.