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Seasonal Changes in Preprandial Glucose, A1C, and Blood Pressure in Diabetic Patients

Response to Liang

Division of Autoimmunity and Transplantation, Walter and Eliza Hall Institute of Medical Research, Parkville, Melbourne, Victoria, Australia

Address correspondence to Margo Honeyman, Autoimmunity and Transplantation Division, Walter and Eliza Hall Institute of Medical Research, 1G, Royal Parade, Parkville, Melbourne, Victoria 3050, Australia. E-mail: honeyman{at}wehi.edu.au

Liang (1) reported seasonal variations in preprandial glucose, A1C, blood pressure, and LDL cholesterol in Taiwanese Chinese type 2 diabetic patients, which correlated inversely with monthly mean temperature, with higher values in the winter and lower values in the summer. We found that mean monthly temperature strongly correlated (r² = 0.76, P = 0.0002) with serum 25-hydroxyvitamin D3 [25(OH)D3] measured monthly in 30 healthy subjects (median age 10.5 years, 15 male subjects). We suggest that Liang’s observations could, instead, be due to variation in vitamin D nutrition, reflected by the seasonal variation in the serum concentration of 25(OH)D3.

A relationship between serum 25(OH)D3 and the parameters measured by Liang has been documented in cross-sectional studies. Thus, low serum 25(OH)D3 was associated with glucose intolerance, as well as diabetes (2) and insulin resistance (3). Serum 25(OH)D3 and homeostasis model assessment of insulin resistance, a validated index of insulin resistance, were inversely associated in a large Caucasoid population (4), and a study of 164 healthy adults found a positive correlation between serum 25(OH)D3 and insulin sensitivity measured by hyperinsulinemic clamp (3). Serum 25(OH)D3 in Japanese type 2 diabetic patients correlated inversely with A1C levels (5), whereas serum 25(OH)D3 and blood pressure correlated inversely in 12,644 subjects in the Third National Health and Nutrition Examination Survey (6) in which serum 25(OH)D was ethnic group–and skin pigmentation–dependent, with non-Hispanic black subjects having the lowest levels and the highest blood pressure, followed by Mexican Americans and non-Hispanic white subjects. Furthermore, supplementation with 25(OH)D3 (700 IU/day) over 3 years resulted in lower fasting plasma glucose levels in Caucasoid adults with impaired fasting glucose compared with placebo control subjects (7).

It would be of great interest, therefore, to know whether the changes in metabolic parameters and blood pressure measured by Liang were mirrored by inverse changes in serum 25(OH)D3.

References

1. Liang WW: Seasonal changes in preprandial glucose, A1C, and blood pressure in diabetic patients. Diabetes Care 30: 2501–2502, 2007[Free Full Text]
   
2. Scragg R, Holdaway I, Singh V, Metcalf P, Baker J, Dryson E: Serum 25-hydroxyvitamin D3 levels decreased in impaired glucose tolerance and diabetes mellitus. Diabetes Res Clin Pract 27: 181–188, 1995[Medline]
   
3. Chiu KC, Chu A, Go VL, Saad MF: Hypovitaminosis D is associated with insulin resistance and beta cell dysfunction. Am J Clin Nutr 79: 820–825, 2004[Abstract/Free Full Text]
   
4. Scragg R, Sowers M, Bell C: Serum 25-hydroxyvitamin D, diabetes, and ethnicity in the Third National Health and Nutrition Examination Survey. Diabetes Care 27: 2813–2818, 2004[Abstract/Free Full Text]
   
5. Suzuki A, Kotake M, Ono Y, Kato T, Oda N, Hayakawa N, Hashimoto S, Itoh M: Hypovitaminosis D in type 2 diabetes mellitus: association with microvascular complications and type of treatment. Endo J 53: 503–510, 2006
   
6. Scragg R, Sowers M, Bell C: Serum 25-hydroxyvitamin D, ethnicity, and blood pressure in the 3rd National Health and Nutrition Examination Study. Am J Hypertens 20: 713–719, 2007[Medline]
   
7. Pittas AG, Stark PC, Harris SS, Dawson-Hughes B: The effects of calcium and vitamin D supplementation on blood glucose and markers of inflammation in nondiabetic adults. Diabetes Care 30: 980–986, 2007[Abstract/Free Full Text]
   

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				W. W. Liang Seasonal Changes in Preprandial Glucose, A1C, and Blood Pressure in Diabetic Patients: Response to Honeyman et al. Diabetes Care, November 1, 2007; 30(11): e119 - e119. [Full Text] [PDF]

This Article Extract Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Honeyman, M. C. Articles by Harrison, L. C. Search for Related Content PubMed PubMed Citation Articles by Honeyman, M. C. Articles by Harrison, L. C. Social Bookmarking                What's this?