Effects of acute insulin-induced hypoglycaemia on psychomotor function: people with type 1 diabetes are less affected than non-diabetic adults

Effects of Sleep Deprivation on Hypoglycemia-Induced Cognitive Impairment and Recovery in Adults With Type 1 Diabetes

OBJECTIVE

To ascertain whether hypoglycemia in association with sleep deprivation causes greater cognitive dysfunction than hypoglycemia alone and protracts cognitive recovery after normoglycemia is restored.

RESEARCH DESIGN AND METHODS

Fourteen adults with type 1 diabetes underwent a hyperinsulinemic, hypoglycemic clamp on two separate occasions. Before one glucose clamp, the participants stayed awake overnight to induce sleep deprivation. Participants were randomized and counterbalanced to the experimental condition. Cognitive function tests were performed before and during hypoglycemia and for 90 min after restoration of normoglycemia.

RESULTS

Cognitive impairment during hypoglycemia did not differ significantly between the sleep-deprived and non-sleep-deprived conditions. However, in the sleep-deprived state, digit symbol substitution scores and choice reaction times were significantly poorer during recovery (P < 0.001) and hypoglycemia symptom scores were significantly higher (P < 0.001), even when symptoms that may have been caused by sleep deprivation, such as tiredness, were removed.

CONCLUSIONS

Hypoglycemia per se produced a significant decrement in cognitive function; coexisting sleep deprivation did not have an additive effect. However, after restoration of normoglycemia, preceding sleep deprivation was associated with persistence of hypoglycemic symptoms and greater and more prolonged cognitive dysfunction during the recovery period.

Effects of acute hypoglycemia on working memory and language processing in adults with and without type 1 diabetes

OBJECTIVE

To examine the effects of hypoglycemia on language processing in adults with and without type 1 diabetes.

RESEARCH DESIGN AND METHODS

Forty adults were studied (20 with type 1 diabetes and 20 healthy volunteers) using a hyperinsulinemic glucose clamp to lower blood glucose to 2.5 mmol/L (45 mg/dL) (hypoglycemia) for 60 min, or to maintain blood glucose at 4.5 mmol/L (81 mg/dL) (euglycemia), on separate occasions. Language tests were applied to assess the effects of hypoglycemia on the relationship between working memory and language (reading span), grammatical decoding (self-paced reading), and grammatical encoding (subject-verb agreement).

RESULTS

Hypoglycemia caused a significant deterioration in reading span (P < 0.001; η(2) = 0.37; Cohen d = 0.65) and a fall in correct responses (P = 0.005; η(2) = 0.19; Cohen d = 0.41). On the self-paced reading test, the reading time for the first sentence fragment increased during hypoglycemia (P = 0.039; η(2) = 0.11; Cohen d = 0.25). For the reading of the next fragment, hypoglycemia affected the healthy volunteer group more than the adults with type 1 diabetes (P = 0.03; η(2) = 0.12; Cohen d = 0.25). However, hypoglycemia did not significantly affect the number of errors in sentence comprehension or the time taken to answer questions. Hypoglycemia caused a deterioration of subject-verb agreement (correct responses: P = 0.011; η(2) = 0.159; Cohen d = 0.31).

CONCLUSIONS

Hypoglycemia caused a significant deterioration in reading span and in the accuracy of subject-verb agreement, both of which are practical aspects of language involved in its everyday use. Language processing is therefore impaired during moderate hypoglycemia.

Type 1 diabetes-associated cognitive decline: a meta-analysis and update of the current literature

BACKGROUND

Type 1 diabetes (T1D) can have a significant impact on brain structure and function, which is referred to as T1D-associated cognitive decline (T1DACD). Diabetes duration, early onset disease, and diabetes-associated complications are all proposed as factors contributing to T1DACD. However, there have been no comparisons in T1DACD between children and adults with T1D. To obtain a better insight into the occurrence and effects of T1DACD in T1D, the aim of the present meta-analysis was to investigate differences between children and adults and to analyse factors contributing T1DACD.

METHODS

Two electronic databases were consulted: PubMed and ISI Web of Knowledge. Literature published up until the end of 2013 was included in the analysis. Effect sizes (Cohen's d), which are standardized differences between experimental and control groups, were calculated.

RESULTS

There was a small to modest decrease in cognitive performance in T1D patients compared with non-diabetic controls. Children with T1D performed worse while testing for executive function, full intelligence quotient (IQ), and motor speed, whereas adults with T1D performed worse while testing the full, verbal and performance IQ, part of the executive function, memory, spatial memory, and motor speed. Episodes of severe hypoglycemia, chronic hyperglycemia, and age of onset can be significant factors influencing cognitive function in T1D.

CONCLUSIONS

The findings in the literature suggest that T1DACD is more severe in adults than children, indicating that age and diabetes duration contribute to this T1DACD.

Acute hypoglycemia impairs executive cognitive function in adults with and without type 1 diabetes

OBJECTIVE

Acute hypoglycemia impairs cognitive function in several domains. Executive cognitive function governs organization of thoughts, prioritization of tasks, and time management. This study examined the effect of acute hypoglycemia on executive function in adults with and without diabetes.

RESEARCH DESIGN AND METHODS

Thirty-two adults with and without type 1 diabetes with no vascular complications or impaired awareness of hypoglycemia were studied. Two hyperinsulinemic glucose clamps were performed at least 2 weeks apart in a single-blind, counterbalanced order, maintaining blood glucose at 4.5 mmol/L (euglycemia) or 2.5 mmol/L (hypoglycemia). Executive functions were assessed with a validated test suite (Delis-Kaplan Executive Function). A general linear model (repeated-measures ANOVA) was used. Glycemic condition (euglycemia or hypoglycemia) was the within-participant factor. Between-participant factors were order of session (euglycemia-hypoglycemia or hypoglycemia-euglycemia), test battery used, and diabetes status (with or without diabetes).

RESULTS

Compared with euglycemia, executive functions (with one exception) were significantly impaired during hypoglycemia; lower test scores were recorded with more time required for completion. Large Cohen d values (>0.8) suggest that hypoglycemia induces decrements in aspects of executive function with large effect sizes. In some tests, the performance of participants with diabetes was more impaired than those without diabetes.

CONCLUSIONS

Executive cognitive function, which is necessary to carry out many everyday activities, is impaired during hypoglycemia in adults with and without type 1 diabetes. This important aspect of cognition has not received previous systematic study with respect to hypoglycemia. The effect size is large in terms of both accuracy and speed.

Diabetes and driving

The principal safety concern for driving for people treated with insulin or insulin secretagogues is hypoglycaemia, which impairs driving performance. Other complications, such as those causing visual impairment and peripheral neuropathy, are also relevant to medical fitness to drive. Case control studies have suggested that drivers with diabetes pose a modestly increased but acceptable and measurable risk of motor vehicle accidents compared to non-diabetic drivers, but many studies are limited and of poor quality. Factors which have been shown to increase driving risk include previous episodes of severe hypoglycaemia, previous hypoglycaemia while driving, strict glycaemic control (lower HbA1c) and absence of blood glucose monitoring before driving. Impaired awareness of hypoglycaemia may be counteracted by frequent blood glucose testing. The European Union Third directive on driving (2006) has necessitated changes in statutory regulations for driving licences for people with diabetes in all European States, including the UK. Stricter criteria have been introduced for Group 1 vehicle licences while those for Group 2 licences have been relaxed. Insulin-treated drivers can now apply to drive Group 2 vehicles, but in the UK must meet very strict criteria and be assessed by an independent specialist to be issued with a 1-year licence.

The effects of acute hypoglycaemia on cognitive function in type 1 diabetes

Throughout life with type 1 diabetes mellitus people with the condition are exposed to multiple episodes of hypoglycaemia associated with insulin therapy. Hypoglycaemia affects several domains of cognitive function. Studies in non-diabetic adults and in people with type 1 diabetes have shown that almost all domains of cognitive function are impaired to some degree during acute hypoglycaemia, with complex tasks being more greatly affected.

The specific cognitive functions of attention and memory are both profoundly impaired during hypoglycaemia. These cognitive processes are fundamental to the performance of many day to day tasks. Their impairment disrupts everyday life and raises safety concerns for the pursuit of activities such as driving.

Mood and emotion are also negatively affected by hypoglycaemia, resulting in tense tiredness, while motivation is reduced, and anger may be generated in some individuals. Hypoglycaemia can cause embarrassing social situations, and may lead to chronic anxiety and depression in people with type 1 diabetes.

At present few therapeutic measures can modify or ameliorate the effects of hypoglycaemia on cognitive function, so instigation of measures to prevent exposure to hypoglycaemia is of major clinical importance, while preserving good glycaemic control.

Self-assessment and objective determination of dexterity in patients with type 1 or type 2 diabetes mellitus

OBJECTIVE

Insulin-treated patients perform complex treatment activities during daily routine, such as blood glucose measurements and insulin injections. We aimed to identify suitable dexterity and cognitive function tests for diabetes patients, and to compare the patient self-assessment of their dexterity skills with the test results (Jebsen-Taylor hand function test, (JHFT), motoric performance test (MLS), number connection test).

METHOD

We enrolled 90 diabetes patients (36 females, 54 males): 15 type 1 with clinically suspected dexterity impairment (A: age: 60 ± 9 years), 30 type 2 with clinically suspected dexterity impairment (B: 61 ± 10 years), 30 type 1 or type 2 patients with visual impairment (C: 64 ± 6 years), and 15 type 1 or type 2 patients without obvious impairment (control group: D: 64 ± 5 years).

RESULTS

There were no differences regarding neuropathy and slight impairments in the number connection test in all groups. Patient self-assessment revealed that 33.4% in group A, 33.3% in group B, 36.7% in group C and 13.7% in group D, considered themselves to have dexterity impairment. However in the JHFT test, all patients from A (100%) and B (100%), 33% from C, and 0% from D presented with dexterity impairment by only passing less than four subtests.

CONCLUSIONS

Impairment of dexterity was much more frequent than believed by the patients themselves. It may be worthwhile to consider these findings when classifying patients regarding their capabilities to perform certain treatments or when assessing diabetes technology with human subjects.

Evaluation of dexterity in insulin-treated patients with type 1 and type 2 diabetes mellitus

BACKGROUND

Daily routine for insulin-treated patients with diabetes mellitus requires correct performance of self-monitoring of blood glucose and insulin injections several times a day. Dexterity skills may play an important role in the performance efficacy of these procedures.

METHODS

We collected data of insulin-treated (>10 years) patients with different age ranges [healthy controls, 14 female/11 male, age (mean ± standard deviation) 55 ± 7 years; type 1 diabetes mellitus (T1DM) patients, 12/13, 45 ± 9 years, disease duration 23.9 ± 6.5 years; T2DM patients, 8/17, 64 ± 6 years, 16.2 ± 6.9 years; T2DM patients (>70 years of age), 9/16, 75 ± 4 years, 19.7 ± 7.0 years]. After assessment of neuropathy (temperature, pain, and vibration perception), the patients participated in two dexterity test batteries [Jebsen-Taylor hand-function test (JHFT) and motoric performance series (MPS)].

RESULTS

Patients with type 2 diabetes showed disturbed vibration perception as compared to the other groups. The dexterity results were influenced by age to a large extent. Older T2DM patients performed worst in the majority of the subtests (e.g., JHFT, writing nondominant hand: control, 40.8 ± 11.7 s; T1DM, 46.3 ± 50.9 s, not significant versus control; old T2DM, 68.1 ± 29.5 s, p < .05; young T2DM, 52.5 ± 26.2 s, p < .05). Patients with type 1 diabetes showed similar JHFT and MPS results than the 10-year-older control subjects and performed outside of the age-dependent normal reference range.

CONCLUSIONS

Manual skills and dexterity differed between the groups, and age-corrected reduced skills were common in both T1DM and T2DM patients in this study. Our findings underline the importance of considering dexterity and manual skills when designing medical devices for patients with diabetes mellitus.

Effects of acute insulin-induced hypoglycemia on spatial abilities in adults with type 1 diabetes

OBJECTIVE To examine the effects of acute insulin-induced hypoglycemia on spatial cognitive abilities in adult humans with type 1 diabetes. RESEARCH DESIGN AND METHODS Sixteen adults with type 1 diabetes underwent two counterbalanced experimental sessions: euglycemia (blood glucose 4.5 mmol/l [81 mg/dl]) and hypoglycemia (2.5 mmol/l [45 mg/dl]). Arterialized blood glucose levels were maintained using a hyperinsulinemic glucose clamp technique. During each session, subjects underwent detailed assessment of spatial abilities from the Kit of Factor-Referenced Cognitive Tests and two tests of general cognitive function. RESULTS Spatial ability performance deteriorated significantly during hypoglycemia. Results for the Hidden Patterns, Card Rotations, Paper Folding, and Maze Tracing tests were all impaired significantly (P < or = 0.001) during hypoglycemia, as were results for the Cube Comparisons Test (P = 0.03). The Map Memory Test was not significantly affected by hypoglycemia. CONCLUSIONS Hypoglycemia is a common side effect of insulin therapy in individuals with type 1 diabetes, and spatial abilities are of critical importance in day-to-day functioning. The deterioration in spatial abilities observed during modest experimental hypoglycemia provides novel information on the cerebral hazards of hypoglycemia that has potential relevance to everyday activities.