Seasonal variation of haemoglobin A1 in children with insulin-dependent diabetes mellitus

Seasonal variation of HbA1c levels in diabetic and non-diabetic patients

Background

Hemoglobin A1c (HbA1c) serves as a pivotal marker for long-term glycemic control. The Diabetes Control and Complications Trial (DCCT) established its relevance, yet gaps exist in understanding potential seasonal variations in HbA1c levels among diabetic patients. The study highlights the need to explore potential seasonal variations in HbA1c levels and their impact on diabetic patients.

Materials and methods

This is an observational study conducted in a tertiary care hospital from January to December 2019, the study analyzed HbA1c levels in 8138 patients. Blood samples were collected using Potassium EDTA-containing vials and processed with an automated analyzer. Seasonal variations were explored using time series analysis.

Results

Mean HbA1c levels peaked during the monsoon (June to September) and were lowest in autumn (October to November). Subgroup analysis revealed differences in patients with HbA1c values below and above 6.5 %. Those with controlled blood sugar showed higher levels in winter (December to February) and monsoon (June to September), while patients with HbA1c values ≥ 6.5 % exhibited significantly lower levels in monsoon (June to September) and autumn (October to November) compared to summer (March to May).

Conclusion

In contrast to global trends, Indian patients demonstrated distinct seasonal variations in HbA1c levels. The highest levels during the monsoon (June to September) may be linked to reduced outdoor activity and dietary changes. The study emphasizes the need for tailored diabetes management considering seasonal influences. Further extensive, longitudinal studies across diverse Indian regions are recommended to comprehensively grasp the impact of seasonal changes on diabetes outcomes.

The impact of ambient temperature on HbA1c in Taiwanese type 2 diabetic patients: The most vulnerable subgroup

BACKGROUND/PURPOSE

The relationship between temperature variability and HbA1c has been reported in Caucasians, but not for Asians of Taiwanese origin. This study investigated the impact of temperature on HbA1c in various groups of Taiwanese with type 2 diabetes in Taiwan.

METHODS

For this longitudinal follow-up study which started in 2006, we recruited a total of 4399 patients with type 2 diabetes who had been regularly followed up at Chi Mei Medical Center and obtained local temperature data for 2006 to 2011 from Taiwan's Central Weather Bureau. We used a generalized estimated equation (GEE) to analyze the HbA1c level and its change over time with temperature and temperature changes, respectively.

RESULTS

We found a negative correlation between HbA1c and temperature (R = -0.475, p = 0.001). For every 1°C decrement in temperature, there was an increase in the risk of having a HbA1c level >7% [p < 0.001, adjusted odds ratio (OR): 1.01]. There was a significantly higher risk of HbA1c > 7% among those in the lowest quartile of temperatures than the highest quartile (p = 0.0038, adjusted OR: 1.13). Patients with diabetic patients were at higher risk of HbA1C > 7% in the winter and spring than those in the summer (adjusted OR: 1.13, p = 0.0027; adjusted OR: 1.14, p = 0.0022). After adjusting for various confounders, we found people who were younger than 65 years old, people who had diabetes for longer than 6 years, and people who had a body mass index (BMI) < 24 to be more susceptible to temperature changes (p = 0.0022, β: 0.0095; p < 0.0001, β: 0.0125; p < 0.0001, β: 0.016, respectively).

CONCLUSION

Our study suggests cold weather may adversely affect HbA1c levels in Taiwanese people with type 2 diabetes, especially in people under 65 years old, people with diabetes for longer than 6 years, and those with a BMI < 24.

Seasonal variation in hemoglobin a1c in korean patients with type 2 diabetes mellitus

A seasonal variation of glucose homeostasis in humans has been reported in various geographic regions. In this study, we examined seasonal variations in hemoglobin A1c (HbA1c) in patients with type 2 diabetes living in Korea. We analyzed 57,970 HbA1c values from 4,191 patients and the association of these values with ambient temperature for 3.5 yr. Overall, HbA1c exhibited its highest values from February to March and its lowest values from September to October (coefficient for cos t = -0.0743, P = 0.058) and the difference between the peak and nadir in a year was 0.16%-0.25%. A statistically significant seasonal variation was observed in the patients who were taking oral anti-diabetic drugs (OADs) without insulin treatment (coefficient for cos t = -0.0949, P < 0.05). The Spearman correlation coefficient between daily HbA1c values and the corresponding 3-month moving average ambient temperature was -0.2154 (95% confidence interval [CI]: -0.2711, -0.1580; P < 0.05). In conclusion, HbA1c values exhibited a seasonal variation in Korean patients with type 2 diabetes, with the highest values during the cold season, particularly in those who were treated with OADs, which should be taken into account in clinical practice for stable glucose control during the cold season.

Geoenvironmental diabetology

Many reports have documented the negative health consequences that environmental stressors can have on patients with diabetes. Studies examining the interaction between the environment and a patient with diabetes can be unified under a single discipline termed "geoenvironmental diabetology." Geoenvironmental diabetology is defined more specifically as the study of how geophysical phenomena impact a patient with diabetes, to include effects on metabolic control, ancillary equipment (e.g., glucometers and insulin pumps), medications, supplies, access to care, and influences on the adaptive strategies employed by patients to care for their diabetes under extreme circumstances. Geological events such as natural disasters (e.g., earthquakes) or extreme weather (e.g., heat waves) are examples of stressors that can affect patients with diabetes and that can be included under the heading of geoenvironmental diabetology. As proposed here, geoenvironmental diabetology refers to how events in the physical world affect those with diagnosed diabetes, rather than how environmental factors might trigger development of disease. As the global prevalence of diabetes continues to increase, including in parts of the world that are especially vulnerable to disasters and climate change, further discussion is warranted on how to best prepare for management of diabetes under conditions of extreme geological and weather events and a changing climate. An overview is presented of various studies that have detailed how geoenvironmental phenomena can adversely affect patients with diabetes and concludes with a discussion of requirements for developing strategies for geoenvironmental diabetes management.

HbA(1c) levels in schoolchildren with type 1 diabetes are seasonally variable and dependent on weather conditions

AIMS/HYPOTHESIS

We evaluated seasonal HbA(1c) changes in children with type 1 diabetes and its relation with measures of weather conditions.

METHODS

HbA(1c) changes over more than 3 years were evaluated in type 1 diabetic patients who were younger than 18 years and had diabetes duration of more than 12 months, and correlated with measures of weather conditions (ambient temperature, hours of sunshine and solar irradiance). After comparison of autocorrelation patterns, patterns of metabolic control and meteorological data were evaluated using Spearman rank correlation.

RESULTS

A total of 3,935 HbA(1c) measurements in 589 school (≥ 7 years) and 88 preschool (<7 years) children were analysed. Mean (± SD) HbA(1c) level for the whole study period was 7.65 ± 1.12%. The lowest HbA(1c) levels were observed in late summer and the highest in winter months, with differences consistently exceeding 0.44%. Autocorrelation analysis of HbA(1c) levels in schoolchildren showed a sine-wave pattern with a cycle length of roughly 12 months, which mirrored changes in ambient temperature. Strong negative correlations of HbA(1c) with ambient temperature (R = -0.56; p = 0.0002), hours of sunshine (R= -0.52; p = 0.0007) and solar irradiance (R = -0.52; p = 0.0006) were present in schoolchildren, but not in preschoolers (p ≥ 0.29 for each correlation).

CONCLUSIONS/INTERPRETATION

Seasonal changes of HbA(1c) levels in schoolchildren with type 1 diabetes are a significant phenomenon and should be considered in patient education and diabetes management. They may potentially affect the results of clinical trials using HbA(1c) levels as their primary outcome, as well as HbA(1c)-based diagnosis of diabetes.

Seasonal fluctuations of glycated hemoglobin levels in Japanese diabetic patients

AIMS

We examined whether glycated hemoglobin (HbA(1C)) levels of Japanese diabetic patients showed seasonal fluctuations.

METHODS

Subjects included 2511 diabetic patients who regularly visited a single diabetic outpatient clinic for 10 years. A total of 253,477 HbA(1C) measurements, as well as sex, age, BMI, type of diabetes, and mode of therapy were extracted from a hospital-based database. For the cross-sectional and longitudinal analyses, average monthly HbA(1C) values of subjects and amplitudes of seasonal fluctuations were calculated. For the time-series analysis, seasonal adjustment factors of each subject were classified as complete, incomplete, or no fluctuation.

RESULTS

Subjects showed a clear seasonal fluctuation of HbA(1C) levels, with highest levels in March (7.69%) and lowest levels in August (7.46%; p<0.001). The amplitudes of the seasonal fluctuations were associated with the mean HbA(1C) levels. The time-series analysis showed that 78.3% of patients had complete or incomplete seasonal fluctuations. HbA(1C) levels were highest in winter-spring and lowest in summer-autumn in most patients; however, some patients showed a reverse pattern.

CONCLUSIONS

Seasonal fluctuations of HbA(1C) levels were recognized in most of the Japanese diabetic patients. Physiological or metabolic factors related to temperature may be the main cause of seasonal fluctuations in HbA(1C) levels.

A multicenter randomized controlled trial of motivational interviewing in teenagers with diabetes

OBJECTIVE

We sought to examine the efficacy of motivational interviewing with teenagers aged 14-17 years with type 1 diabetes.

RESEARCH DESIGN AND METHODS

In a randomized controlled trial analyzed by intention to treat, 66 teenagers with type 1 diabetes attending diabetes clinics in South Wales, U.K., were randomly assigned to the intervention group (38) and control group (28). Teenagers in the intervention group received motivational interviewing, and the control group received support visits. All participants received individual sessions over 12 months. The main outcome measures assessed at baseline, 6, 12, and 24 months were serum A1C and psychosocial self-report questionnaires including quality of life and well-being measures.

RESULTS

At 12 months, 60 patients had complete data. At the end of the intervention (12 months), the mean A1C in the motivational interviewing group was significantly lower than in the control group (P = 0.04), after adjusting for baseline values. At 24 months (when n = 47), this difference in A1C was maintained (P = 0.003). There were differences in psychosocial variables at 12 months, with the motivational interviewing group indicating more positive well-being, improved quality of life, and differences in their personal models of illness (all P < 0.01). Some of these differences were maintained at 24 months.

CONCLUSIONS

Motivational interviewing can be an effective method of facilitating behavioral changes in teenagers with type 1 diabetes with subsequent improvement in their glycemic control.

Environmental triggers and determinants of type 1 diabetes

Type 1 diabetes is perceived as a chronic immune-mediated disease with a subclinical prodromal period characterized by selective loss of insulin-producing beta-cells in the pancreatic islets in genetically susceptible subjects. A series of evidence supports a critical role of exogenous factors in the development of type 1 diabetes, such as 1) the fact that <10% of individuals with HLA-conferred diabetes susceptibility do progress to clinical disease, 2) a pairwise concordance of type 1 diabetes of <40% among monozygotic twins, 3) a more than 10-fold difference in the disease incidence among Caucasians living in Europe, 4) a several-fold increase in the incidence over the last 50 years, and 5) migration studies indicating that the disease incidence has increased in population groups who have moved from a low-incidence to a high-incidence region. This article discusses the trigger-booster hypothesis claiming that the diabetic disease process is triggered by an exogenous factor with definite seasonal variation and driven by one or several other environmental determinants. In addition, there are a series of modifying factors affecting the fate and pace of the process. Accordingly, progression to clinical type 1 diabetes typically requires the unfortunate combination of genetic disease susceptibility, a diabetogenic trigger, and a high exposure to a driving antigen.

Continuous glucose monitoring in children with type 1 diabetes: before and after insulin pump therapy

OBJECTIVE

The aim of continuous subcutaneous insulin infusion (CSII) therapy in patients with type 1 diabetes mellitus (T1DM) is to mimic as closely as possible the normal physiologic pattern seen in individuals without diabetes. This study was undertaken to determine the specific areas of improved glycemic control in subjects after initiation of insulin pump therapy and times where further improvement is needed.

RESEARCH DESIGN AND METHODS

Eight patients with T1DM (age 7.5-17 yr) wore the Continuous Glucose Monitoring System (CGMS) (Medtronic MiniMed, Northridge, CA, USA) for 3 d before and 3 months after initiation of insulin pump therapy. The CGMS, which measures inter- stitial glucose concentrations every 5 min for a 72-h period, was used to evaluate glucose profiles. Patients entered 4-5 fingerstick blood glucose measurements daily into the sensor for calibration. Detailed logs of food intake, exercise, and hypoglycemic symptoms were also recorded.

RESULTS

Hemoglobin A1c (HbA1C) was reduced (p < 0.007) following 3 months of insulin pump therapy. Post-CSII continuous glucose profiles demonstrated an overall improvement in hourly mean glucose over a 24-h period (p < 0.001) as well as a reduction in the area under the curve for glucose (27 +/- 4 prepump vs. 8.6 +/- 1.4 mg/dL/d postpump, p < 0.004). This improvement was a result of an attenuation of the maximal postprandial glycemic excursions. Postbreakfast 349 +/- 24 vs. 267 +/- 16 mg/dL, p < 0.003; lunch 340 +/- 16 vs. 217 +/- 20 mg/dL, p < 0.003. Postdinner average similarly decreased after 3 months of CSII by 22%, p < 0.04.

CONCLUSIONS

Pump therapy specifically improved the postprandial glucose excursions in children.

Comparative trial between insulin glargine and NPH insulin in children and adolescents with type 1 diabetes mellitus

The objective of this study was to compare the efficacy and safety of insulin glargine, a long-acting insulin analog, with NPH insulin in children and adolescents with type 1 diabetes mellitus (T1DM). In a multicenter, open-label, randomized, 6-month study, 349 patients with TIDM, aged 5-16 years, received insulin glargine once daily or NPH insulin either once or twice daily, based on their prior treatment regimen. Although there was no significant difference between the NPH insulin and insulin glargine treatment groups with respect to baseline to endpoint change in HbA1c levels, fasting blood glucose (FBG) levels decreased significantly more in the insulin glargine group (-1.29 mmol/l) than in the NPH insulin group (-0.68 mmol/L, p = 0.02). The percentage of symptomatic hypoglycemic events was similar between groups; however, fewer patients in the insulin glargine group reported severe hypoglycemia (23% vs 29%) and severe nocturnal hypoglycemia (13% vs 18%), although these differences were not statistically significant (p = 0.22 and p = 0.19, respectively). Fewer serious adverse events occurred in the insulin glargine group than in the NPH insulin group (p < 0.02). A once-daily subcutaneous dose of insulin glargine provides effective glycemic control and is well tolerated in children and adolescents with T1DM.

Gender differences in glycosylated hemoglobin levels in seasonal affective disorder patients and controls

Seasonal affective disorder (SAD) has been shown to manifest different symptoms in female and male patients. Specifically, women with SAD have been shown to have greater increases in overeating, weight gain, and increased sleep as compared with their male counterparts. Given these dietary changes, we predicted that female SAD patients would exhibit increased glycosylated hemoglobin (HbA1) levels, indicative of chronically elevated glucose levels. Twenty-two patients (15 women and seven men) and matched controls were enrolled during the winter season and tested for HbA1 levels. A three-way analysis of variance (ANOVA; gender x group x season) was insignificant and the result was a negative study. After the initial hypothesis was rejected, we undertook a post-hoc analysis of the data, from which emerged that in winter, women patients had higher HbA1 levels as compared with matched controls. As our original hypothesis was rejected, we cannot accept the results of the post-hoc study. However, numerous other studies have demonstrated that female and male SAD patients differ in their pathophysiology, and are suggestive that in future analyses ought to consider analyzing subjects separately across gender.

Seasonality of presentation of type I diabetes mellitus in children. Scottish Study Group for the Care of Young Diabetics

Environmental influences are thought to have an aetiological role in onset of diabetes in children. Month of onset in over 2000 children in Scotland was established and there was an excess in colder/darker months than in warmer/lighter months. A meta-analysis of 21 previous studies with over 13,000 patients gave the same result at a much higher level of significance. A mechanism is postulated based on previous viral induced islet cell damage with ongoing progressive auto-immune destruction. There may be physiological seasonal changes with winter stress on carbohydrate and lipid metabolism. The raised winter levels of pituitary, adrenal and thyroid hormones fail to be antagonised by falling level of insulin. A role for seasonal variation in exercise and nutrition is considered.

Glycemic control in diabetes mellitus: have changes in therapy made a difference?

PURPOSE

New methods of measuring and controlling glycemia in diabetes mellitus have been developed and implemented in the past 10 years. We examined whether glycemia, as measured by glycosylated hemoglobin, changed in outpatient insulin-dependent diabetes mellitus (IDDM) and noninsulin-dependent diabetes mellitus (NIDDM) populations between 1985 and 1993 and whether contemporaneous changes in therapy could account for observed changes in glycemia.

PATIENTS AND METHODS

Outpatients were selected based on having glycated hemoglobin (HbA1c) measured in the Massachusetts General Hospital laboratory during March 1985 (IDDM n = 94 and NIDDM n = 137) or during March 1993 (IDDM n = 89 and NIDDM n = 118). Chart reviews established demographic and clinical characteristics, including frequency of blood glucose self-monitoring, insulin injections, office visits, and HbA1c measurements during the year prior to the HbA1c result.

RESULTS

Mean HbA1c level was significantly lower in the 1993 IDDM cohort compared with the 1985 cohort (8.77% +/- 1.7% versus 9.47% +/- 2.1%, P = 0.014). In the NIDDM cohorts, the difference in mean HbA1c did not achieve statistical significance (8.35% +/- 1.6% in 1993 versus 8.75% +/- 2.1% in 1985, P = 0.09); however, when adjusted for differences in NIDDM duration, HbA1c in the 1993 cohort was significantly lower than that in the 1985 cohort. The largest decrease in HbA1c in NIDDM was in patients treated with insulin (9.53% +/- 2.0% versus 8.54% +/- 1.5% in 1985 and 1993, respectively, P = 0.004). Multiple linear regression analyses demonstrated that increased frequency of self-monitoring and of insulin injections were associated with lower HbA1c in IDDM.

CONCLUSIONS

The level of average glycemia has decreased in IDDM patients over the past 8 years, attributable, at least in part, to an increased frequency of monitoring and of insulin injections. Glycemia decreased in NIDDM, especially in the subset of patients treated with insulin. This temporal shift in glycemic control should have a salutary effect on the development of long-term microvascular and neurologic complications.